R A D I O L O G Y A N D E M P H Y S E M A *

GEORGE SIMON, F.F.R.

Radiologist, St Bartholomew's and Brompton Hospital

EMPHYSEMA has been defined as abnormally large air spaces beyond the terminal bronchiole (Ciba symposium, 1959). There are many types of emphysema, some clinically important, others less so, and one classification is that of Lynne Reid (1964) which is factual, and has the advantage that it can be related to clinical severity since it partly bridges the gap between structure and function (Table 1).

On this occasion it is proposed to concentrate on gross widespread emphysema with air trapping, due either to chronic bronchitis or else idiopathic, and the first case is a typical example., She was a lady of forty-three, who six years previously had had an attack of 'bronchitis', that is an acute respiratory infection, with fever, Cough and yellow sputum. The infection subsided but the cough and sputum persisted, the sputum becoming mucoid. Later she became very breathless on exertion, and finally could barely walk one hundred yards.

The result of some respiratory function studies at this stage are shown in Table 2 and these would support the clinical diagnosis of gross emphysema.

She died soon after of respiratory insufficiency. Morbid anatomical examination showed large surface bullae bulging out from both lungs, and the lungs did not deflate so that there was evidence of air trapping. Section of the lung (Fig. 1) showed a gross degree of pan-acinar and centri-acinar (centri-lobular) emphysema (Grades III and IV over two-thirds of slice). Histologically dilated and hypertrophied mucous glands were found in the larger bronchi, confirming the clinical diagnosis of chronic bronchitis (gland/wall ratio:0.5).

THE X-RAY DIAGNOSIS

The criteria for the radiological diagnosis of gross widespread emphysema (Table 3) chosen

TABLE 1

CLASSIFICATION OF EMPHYSEMA AFTER REID, L. (1964)

EMPHYSEMA

I WITH,OU'i' AIRWAYS OBSTRUCTION

(without 'air trapping') Aged lung I d i opa th i c ~ periocinar or paraseptol

e m p h y s e m a ~ - ~ Centr/Qci~or

Coal-storage pneumoconiosis Compensatory emphysema

I WITH AIRWAYS OBSTRUCTION

(with 'air trapping')

[ I Reversible Airways Irreversible Airways

Obstruction Obstruction Bell valve large bronchus

I I Without Organic With Organic

Bronchial Disease Bronchial Disease Primary or essential emphysema Childhood lobar emphysema

A(16)

I Developmental

Atresia of bronchus

* Skinner Lecture, 1963

293

I Acquired

Scar emphysema Branchia/iris obliterans and

bronchitis obliterans- a) in childhood, os in

unilateral tronsrodi~ncy ~) in adult, os in chronic

bronchitis

294

F.V.C.

F.E.V.i

M .V.V.

Peak flow

Dco ,

O3

pCOz •

C L I N I C A L R A D I O L O G Y

TABLE 2 TABLE 3

RESPIRATORY FUNCTION TESTS OF CASE 1 CRITERIA FOR THE X-RAY DIAGNOSIS O17 EMPHYSEMA

1400

600 (43 %)

20 L/rain.

70 L/min.

6.6

98%

44 ram. Hg.

I. Excess of air in the lungs Low flat diaphragm. Large retrosternal translucent area.

2. Cardiovascular changes Narrow vertical heart. Prominence of pulmonary trunk. Large hilar with small lung vessels.

3. Bullae

Avascular transradiant area. May be demarcated by a white line. May have no definite border.

Fro. 1

FIG. 1--Morbid anatomy--section of lung of case 1. White arrow points to Grade IV emphysema, black to Grade III. Rather more than two-thirds of the largest lung slice was Grade l l I to IV pan-acinar emphysema. FIG. 2--Standard chest radiograph of case 1. Woman aged forty-three. Six years cough and sputum. Now severe dyspnoea. Low fiat dia- phragm. Heart 9 cm. Large hilar and small lung vessels. In the original avascular areas, upper and lower zones with

some hair-line shadows.

empirically by Simon and Galbraith (1953) were threefold :--

1. An excess of air in the lungs with air trapping demonstrated by a low, flat and poorly moving diaphragm and a large retrosternal translucent area. Overall blackening of the film was not accepted as a sign of excess of air, since the blacken- ing also depends on the thickness of the patient, the exposure given and the contrast produced by development.

2. Certain changes .in the appearance of the heart contour and lung vessels, particularly a narrow vertical heart, a large pulmonary trunk, and a combination of large hilar vessels with small lung vessels.

FIG. 2

3. The presence of bullae or bullous areas demonstrated by localised avascular relatively translucent areas.

When all three criteria were fulfilled (Fig. 8), the diagnosis was made with some certainty, but could still be made with only the first two, or occasionally when the first and last were obvious but the second indefinite. All three criteria are fulfilled in the radiograph of the first patient (Fig. 2) whose lung has already been illustrated (Fig. 1).

EXCESS OF AIR

The low fiat diaphragm.--The diaphragm can be considered low if the central portion of the right

R A D I O L O G Y A N D E M P H Y S E M A 295

FIG. 3 A--Emphysema. Flat diaphragm. Retrosternal translucent area 5 cm. deep, in emphysema reaching to within 5 cm. of dia-

phragm. B--Normal. Similar distances 2.5 and 7 cm.

dome on inspiration lies at or below the level of the 7th rib anteriorly, a feature shown in Figure 2. The 6th rib is acceptable if the patient is of the hypersthenic build. Occasionally a normal person of asthenic build may show a diaphragm as low as the 7th rib anteriorly, but the superior convex curve is usually maintained. In emphysema the diaphragm on full inspiration tends to loose its even superior convex curve, and tends to run in an almost straight line either horizontally (Fig. 2), or sloping downwards and outwards. The flattening is usually confirmed (or in a doubtful case may be more clearly seen) in a lateral view, when the shadow tends to run from the back to the front in an almost horizontal line (Fig. 3A). It may even be concave superiorly in a severe case.

The range of movement between full inspiration and full expiration is diminished and is usually less than 3 cm. The normal range for a person in a comparable age group (forty-five to sixty-five) is 3 to 10 cm.

In some cases of emphysema the diaphragm on full expiration is no longer flat and regains its normal superior convex curve. In others the shape is normal even on inspiration, but the range of movement is much restricted.

Not to be confused with a low flat diaphragm is the shadow of an unusual bilateral pleural effusion which may have a relatively horizontal but not low upper margin. A low flat diaphragm

is occasionally seen following a pleural effusion, but in such a case the change is usually unilateral.

The large retrosternal translucent zone.--The depth of the translucent zone behind the sternum representing the two lungs in contact in front of the aorta is abnormally great in emphysema, and often measures 3 to 5 cm. (Fig, 3A) compared with the normal of 2 to 3 cm. (Fig. 3B). The selection of a measuring point on the ascending aorta presents some difficulty, but can usually be done with sufficient fairness to make such measure- ments reliable.

The retrosternal translucent zone also tends to extend down lower in emphysema than in a normal person, often reaching within 1 to 2 cm. of the diaphragm in emphysema (Fig. 3A), whereas it is rarely lower than 3 cm. in a normal person (Fig. 3B). In some cases of emphysema the translucent zone is both deep and low, in others low without being deep.

It might be thought that the increase in the size of the retrosternal translucent zone was related to the increasing kyphosis with age, but this is not so since observation of seventy-two more or less normal persons between the ages of seventy-five and ninety-nine showed severe or moderate kyphosis in 68 per cent and yet in none of them was the retrosternal translucent zone enlarged (Edge and Simon 1964). It will, however, be enlarged in a normal person if the sternum shows gross anterior convex curvature.

296

CARDIOVASCULAR CHANGES

The narrow vertical heart .--In emphysema the heart tends to be narrow, the criterion chosen for this being a transverse diameter of 11.5 era. or less. It seems to have a rather vertical lie with little prominence of either border in the lower half (Fig. 2). This phenomenon of the narrow vertical heart is probably in part or perhaps mainly the result of the low position of the diaphragm which allows the heart to become more dependent and therefore narrower. A narrow vertical heart is sometimes seen in a normal person, but this is not common.

Prominence of the pulmonary artery.---A slight or moderate prominence of the left heart border below the aortic knuckle due to the main pulmon- ary artery is often seen in emphysema (Fig. 5). This effect may be due in part to rotation of the heart following from its more dependent position and in part to a real dilatation. This~sign is not present in every case of gross widespread emphy- sema. In the first case shown, with the pathological confirmation of the diagnosis, there is no promi- nence of the pulmonary trunk (Fig. 2), though all the other radiological criteria for the diagnosis are present.

When the enlargement of the pulmonary artery

CLINICAL RADIOLOGY

shadow is quite marked (Fig. 4) it usually means the emphysema is severe but is not necessarily an indication that pulmonary hypertension has de. veloped. In this particular case the E.C.G. Was normal and at post-mortem there was indeed gross emphysema, but there was no right ventricular hypertrophy.

The position is confused for the radiologist, since there is some doubt which are the best criteria in the E.C.G. on which to base a diagnosis of right ventricular hypertrophy. The criteria laid down by Goodwin and Abdin (1959) are rather elaborate and not widely used, nor is correlation of the E.C.G. grading with the actual size or weight of the right ventricle very close. In a series of 100 chronic bronchitics attending an out-patient clinic, there were twenty-three who showed an emphysema pattern in the radiograph, and only four of these showed E.C.G. evidence of right ventricular hypertrophy by either the above or less stringent standards (Table 4).

Cardiac catheter recordings of pulmonary artery pressure are undertaken on too few of these patients to assess the relation of the radiological findings to the pulmonary artery pressure. It seems to be generally believed that the pulmonary artery pressure is within the normal range, but rises unduly on exercise. This observation can hardly relate to many of the patients with radiological evidence of gross emphysema, since many of them are unable to undertake any vigorous exercise or can do so for such a short time in the day that the pressure rise would probably be too short in any twenty-four- hour period to cause pulmonary artery dilatation.

Large hilar vessels with small mid-lung vessels.--A most important finding in general emphysema is the combination of relatively large hilar vessels

TABLE 4

INCIDENCE OF RIGHT VENTRICULAR HYPERTROPHY IN PATIENTS SHOWING THE EMPHYSEMA PATTERN I N THE RADIOGRAPH, AND INCIDENCE OF 'POSSIBLE SLIGHT' GENERAL EMPHYSEMA, LOCAL,

AND GROSS WIDESPREAD EMPHYSEMA,

(The first 100 of a series of patients with chronic bronchitis being investigated by Dr J. C. Batten at the Brompton Hospital.)

FIG. 4 Emphysema. Male aged fifty-two. Nine years cough, mucoid sputum, increasing dyspnoea. Low diaphragm. Avascular upper zones. Very large main trunk of pulmonary artery, but no right ventricular hypertrophy either on the E.C.G. or

post-mortem. Gross emphysema post-mortem.

Normal radiograph 59

Possible slight general emphysema. 7

Local emphysema only 11

Gross widespread emphysema 23

Unequivocal E.C.G. evidence of R.V.H. four cases, all gross widespread emphysema.

Later 12 per cent of those with a normal radiograph and 36 per cent of those with an emphysema pattern showed R.V.H.

R A D I O L O G Y AND E M P H Y S E M A 297

a r t e r y , l~arge l l l l a r W l t l l b l l l i l l l l U l l g t ¢ ~ 3 F 1 O , O U l t l ~ , l l l l l l -

Fro. 5 line shadows upper zones. Fro. 6--Emphysema. Hilum level tomogram. Male aged forty-one. Cough, sputum and dyspnoea many years. Plain radiograph similar to Figure 5. Measurement B.2 (dots) descending artery to translucency of intermediate bronchus. 'A' from upper lobe bronchus to top of left pulmonary artery. Arrows point to trans-hilar measuring points. Note large right lower lobe artery and left upper lobe

artery and veins.

with relatively small mid-lung vessels (Fig. 5). This appearance is probably related in some way to the loss of capillary bed, and will therefore only be seen when the emphysema and therefore the capillary bed loss is severe.

When viewing the vessels, it is useful to note the difference in size between the hilar and adjacent mid-lung vessels of the next two or three genera- tions. In a normal person the reduction in size from the hilum to the periphery appears to be gradual, and large hilar vessels are associated with relatively large lung vessels, while small hilar vessels are associated with relatively small lung vessels. In emphysema large hilar vessels lead to what appear to be relatively small lung vessels almost at once (Fig. 5). In some cases this change is widespread, but in others one or two of the vessels remain large for some distance into the lung fields. In Figure 5 for instance, the uppermost vessels and those at the right base remain relatively large, although the other vessels are small. This uneven distribution of the vessel narrowing may occur when most of the blood is diverted to one or two areas where presumably the lung is less affected and the capillary loss is less. Some vessels, whether small or large, are cut off short before entering a bullous area, or appear to have fewer side

branches than normal, an effect described as pruning. Nevertheless in a non-bullous area vessel shadows can be seen as far laterally towards the pleura as in a normal person.

Some vessels seem to end adjacent to the hair- line shadow of the wall of a bulla, which may be seen extending outwards towards the periphery from the end of the vessel shadow, which gives the appearances of stretching of the vessel.

Confirmation of the change in artery size by lomography.--Judgement of the size of the hilar and lung vessels in a radiograph is usually based on a subjective impression and is therefore suspect as evidence. More precise evidence has been obtained from a series of posterior view tomograms of a group of patients suspected of or later known to have gross emphysema, and a group of persons with no particular respiratory symptoms but of a similar age. These tomograms were taken with the subject supine and with the same x-ray machine and a multisection box starting at the same layers between 14 to 12 cm., and therefore the magnification factors were reasonably constant. The exposure time was two seconds, so the artery shadow presumably represented the systolic size.

Only certain vessels could be seen clearly enough in all cases for a useful comparison to be made

298 CLINICAL RADIOLOGY

TABLE 5

EMPHYSEMA AND NORMAL PATIENTS. COMPARISON OF MEASURE- MENTS FROM HILUM LEVEL TOMOGRAMS

Trans-hilar

Right B2

Left A

Normal (mm.)

119

13"8

24"l

Emphysema (ram.)

147

21'5

36

Chronic lung disease, normal

x-ray (mm.)

134

15"5

32

between the emphysema and the normal groups. For instance the main descending artery on the right was constantly seen (Fig. 6), and a point was chosen roughly half way along it on its lateral border, and a measurement made horizontally to the translucency of the intermediate bronchus lying medial to the artery. This is referred to as measurement B.2 in Figure 6 and Table 5. Another useful though artificial measurement was made from the upper margin of the translucency of the left upper lobe bronchus to the top of the shadow roughly corresponding to the main left pulmonary artery. This was named measurement A. The trans-hilar measurement was made from the point

where the upper lobe vein meets the descending artery on either side (Fig. 6, opposite arrow).

All three of these measurements were on an average larger in the emphysema than in the normal group (Table 5).

It has so far not been possible to prove by tomography that the mid-lung vessels are smaller than normal, partly because of their very small size and partly because of the difficulty of identi. fying similar vessels at similar levels from case to case. In one case of unilateral emphysema it was possible to see both in the plain radiograph and in the tomograms that the vessels in the bullous right lower lobe were smaller than those in the pre. sumably normal left lower lobe. In this case a mid-lung artery in the right lower zone measured about 3 mm., while an artery of a similar genera- tion on the left was 4"5 ram.

Micropaque injection of pulmonary arteries in specimen.--The emphysema pattern of large hilar with small lung vessels has been confirmed in some cases where the lung has been available either at post-mortem or after resection. The lung after removal is inflated and the artery injected with micropaque and the specimen is then radiographed.

The artery size in an emphysematous (Fig. 7A) and a normal lung (Fig. 7B) are illustrated and

FIG. 7 A--Emphysema (radiograph during life similar to Fig. 5). Post-mortem, emphysema Grade III to IV con- firmed. Injection of pulmonary artery with micropaque. B--Similar injection of a normal lung for

comparison.

R A D I O L O G Y A N D E M P H Y S E M A

TABLE 6

DIAMETERS OF VARIOUS ARTERIAL BRANCHES MADE FROM THE ORIGINAL RADIOGRAPHS OF FIGURE 7A

Hilum

After three branches

After six branches

Diameter of artery

Normal Emphysema (mm.) (mm.)

18 28

12 18

10 12

the actual measurements recorded in Table 6. In this instance the emphysematous lung starts with an artery size 10 mm. greater than the normal lung, and after six generations the difference is only 2 ram.

In the normal lung the artery size seems to be much the same in the in vivo radiograph and in the micropaque injected specimen, whereas if a relatively avascular translucent area is examined in both types of radiograph, the arteries seem larger in the radiograph of the specimen.

299

BULLAE

A third criterion for the diagnosis of emphysema is based on a combination of the first two, con- sisting of an excess of air giving a localised relatively transradiant area, together with few or no vessel shadows within it, an appearance indicating a bulla or bullous area.

A bulla may be demarcated by a hair-line shadow (Fig. 8) or if it is not so demarcated may be called a bullous area. The distinction is rather uncertain radiologically since the hair-line may be invisible in an anterior view but clearly seen in a lateral view (Fig. 9). Morbid anatomical study may show either a single large air space or sac, or relatively small alveolar dilatations with the lung architecture more or less intact, and with normal filling of the larger vessels after micropaque injection of the specimen.

In a series of seventy-six cases of widespread general emphysema with bullae the large and obvious major bullae or bullous areas were pre- dominantly in the upper half in thirty-three, in the lower zones in twenty-seven and in both the upper and lower zones in sixteen.

The importance of well demarcated bullae as a sign of widespread gross emphysema is not very

FIG. 8 FIG. 9 FIG. 8--Emphysema with large bullae. Male aged fifty-two. Cough, sputum and increasing dyspnoea. Large avascular rela- tively transradiant areas both upper zones--on the right (above arrow) demarcated by a hair-line shadow, on the left ill defined. FIG. 9--Emphysema. Same patient as Figure 8 (lateral view). The ill-defined avascular area in the lower zone is now well

demarcated by a hair-line shadow (opposite arrow). Also large retrosternal translucent area extending low.

300 C L I N I C A L R A D I O L O G Y

TABLE 7

A SERIES OF 299 PATIENTS WITH CHRONIC BRONCHITIS, SOME WITH EMPHYSEMA, SHOWlNO INCIDENCE OF BULLAE

Number with emphysema

Emphysema with obvious bullae

Emphysema without obvious bullae

87 33 (½)

54 (3)

great. In fact such a bulla was only seen in a third of all the cases in one series (Table 7). On the other hand, in a doubtful case, for instance where the diaphragm is low and flat, but the vessels almost normal, the presence of a bulla or bullous area will indicate gross widespread emphysema.

Bullae in local emphysema.--A bulla may occur as an isolated phenomenon, the rest of the lung and the other lung being normal both radiologically and on pathological examination. An example is the case illustrated in Figure 10, a man of forty- two without symptoms, a common finding in this condition even when, as here, the bulla is very large. At thoractomy a huge air-containing bulla was found occupying only a part of the upper lobe. There were a few smaller bullae just below it, otherwise the rest of the upper lobe and the lower lobe appeared normal. The buUa was removed with good re-expansion of the remaining lung.

Because such bullae may not cause symptoms, it is suggested that such cases be excluded as examples of widespread general emphysema and classified as local emphysema. For prognostic purposes or in epidemiological surveys they can even be grouped with patients showing a normal radiograph.

RELIABILITY OF X-RAY DIAGNOSIS

Whenever widespread emphysema has been diagnosed on the basis of the foregoing criteria (Table 3) and morbid anatomical studies have been possible, then gross widespread emphysema with air trapping has invariably been found such as that illustrated in Figure 1. Such confirmation has been seen in over fifty cases, ten of which are described by Reid and Millard (1964) (see page 307).

In most cases in which the emphysema pattern is seen radiologically, severe dyspnoea and the appropriate physical signs and respiratory function tests will give clinical support to the diagnosis. In a few, dyspnoea becomes a prominent feature one or two winters after the radio!ogical diagnosis has been made. When the emphysema is due to chronic bronchitis there will also b e cough and sputum. The sputum tends to be purulent and of

FIo. 10 Localised emphysema. Male aged forty-two. Asymptomatic. Transradiant avascular area upper part left lung, demarcated below by a hair-line shadow (above arrow). Right lung normal. Bulla confirmed, with left lower lobe compressed by it, but normal. Good re-expansion after removal of bulla which

occupied only a part of the upper lobe.

moderate amount but may be scanty and mucoid. When the emphysema is idiopathic there may be no cough or sputum. It must be admitted that the reliability of sputum histories is not always great, however careful the questionnaire.

Respiratory function studies invariably showed severe airways obstruction, more or less irreversible, and a low Dco in those patients with the radiological emphysema pattern, whereas such changes were only seen in some cases of chronic bronchitis with a normal chest radiograph.

PROGNOSIS

Once an obvious emphysema pattern can be seen in the radiograph the prognosis is rather poor. In a five year follow-up of patients with chronic cough and sputum presumed due to chronic bronchitis (Medvei and Simon 1962), only 47 per cent of those showing the classical emphysema pattern were alive at the end of the period as compared with 79 per cent of those in whom the radiograph was normal or showed evidence of local emphysema only.

R A D I O L O G Y A N D E M P H Y S E M A 301

WHETHER A NORMAL RADIOGRAPH EXCLUDES GROSS EMPHYSEMA

If the case for the reliability and value of the radiological 'emphysema pattern' is accepted, there remains the question whether a normal radiograph excludes either gross widespread emphysema with air trapping as a pathological finding, or clinically significant degrees of emphysema as a cause of dyspnoea; and in addition how severe the emphy- sema must be in terms of pathology or respiratory function tests before an x-ray diagnosis is possible.

The answer to these questions will depend on a reliable pathological grading and its careful cor- relation with the x-ray findings. This is neither easy nor simple because three different and import- ant factors must be taken into account.

Firstly, the type of emphysema must be defined. Whereas pan-acinar emphysema is usually clinically significant, centri-acinar (centri-lobular) emphy- sema or paraseptal emphysema may be present without air trapping, and therefore often without clinical significance or radiological changes. Para- septal emphysema particularly along the lung margins may be quite severe and, whether visible or not radiologically, without symptoms.

Secondly, the degree of severity of pan-acinar emphysema must be established by measuring the size of the dilated air spaces in a suitably inflated specimen.

Finally, the distribution must be taken into account, especially whether it is widespread throughout the lungs, widespread only in certain regions of the lungs, or patchy in distribution with collections of less affected or normal alveoli between. When it is patchy in distribution the possible effect on nearby normal areas of the air trapping in the dilated air spaces must also be taken into account.

Reid and Millard (1964) (see page 307)have graded the lung changes according to the size of the air spaces and the degree of lung retraction, both of these being an indication of the lack of lung substance, and related them to the radiographic appearances.

Froffi-this study it can be seen that the milder grades of emphysema, even when they are uniform and widespread throughout the lungs, do not cause abnormalities in the radiograph. With the middle grades, the presence or absence of radiographic changes may depend largely on the distribution of the emphysema, while severe grades if fairly widespread invariably give radiological changes, a finding also observed by Laws and Heard (1962).

It is possible for a patient to have severe dyspnoea clinically, due to irreversible airwltys obstruction

from chronic bronchitis and yet have a normal radiograph.

All these findings support the view that a ncrmal~ radiograph does almost exclude gross widespread emphysema.

SPECIAL CIRCUMSTANCES IN WHICH THE RADIOGRAPHIC APPEARANCES

MAY BE MISLEADING

In certain circumstances the radiographic evi- dence may be misleading unless it is carefully correlated with the other findings.

One is when gross widespread emphysema is associated with cor pulmonale either in clinical failure or on the verge of this. A man aged fifty- eight years had a long history of cough and sputum which was usually mucoid. Recently dyspnoea had become more severe, and he had ankle oedema and a raised jugular venous pressure. The oxygen saturation dropped to 81 per cent, and the plasma CO~ rose to 67 ram. Hg. The radiograph shows a diaphragm of almost normal Shape at the level of the 7th rib, a large heart shadow with a transverse diameter of 15 cm., and large hilar with relatively large lung vessels (Fig. l lA). It would not be possible to diagnose emphysema from such a radiograph. By good fortune a pre-existing radio- graph was available (Fig. llB). This shows a typical 'emphysema pattern', with the diaphragm lower (7th interspace) and flat, the heart shadow smaller at only 11.3 cm. and narrow and vertical, and the hilar vessels appearing relatively large and contrasting well with the smaller mid-lung vessels. If a previous radiograph is not available, and the patient recovers from the heart failure, a later radiograph may also show an 'emphysema pattern' which was not visible during the incident of heart failure.

Dr Lynne Reid has made the suggestion that, in such a case, owing to the heart failure, the circulation through the lung is altered and some of the trapped air is absorbed. A rise in the position of the diaphragm would follow, which together with the anoxia would cause the heart shadow to appear larger. Because of the vessel engorgement, the mid-lung vessels will no longer appear narrowed, a change most readily seen in the large pulmonary veins.

This pitfall of x-ray diagnosis will not arise if the clinical state of the patient is taken into considera- tion when conclusions are made about the x-ray appearances. It would be a certain source of error in any emphysema trial if the radiographs were read in isolation.

302 C L I N I C A L R A D I O L O G Y

Fm. 11 A--Emphysema with cor pulmonale in failure. Male aged fifty-eight. Cough, sputum and dyspnoea, recently severe. Ankle oedema, raised J.V.P. Diaphragm curved. Heart 15 cnl. Large hilar and mid-lung vessels. B--Same patient as Figure I1A, but seven months previously. Diaphragm lower and now flat. Heart 11.3 cm. Hilar vessel much the same and large, but

mid-lung vessels appear smaller. In fact classical 'emphysema pattern'.

Another special circumstance may be emphysema in an obese hypersthenic individual. In such a person moderate emphysema would fail to depress an initially high diaphragm sufficiently for it to appear low and flat. However , in some cases it may be as low as the 6th rib anteriorly, which is acceptable as a low position in a patient of this build. In such a patient the hilar vessels are often initially small, and some enlargement would still appear to be within the normal range and could not therefore be detected without previous radio- graphs taken before the emphysema had developed. Incidentally such patients may have dyspnoea from a combination of the adiposity and the under- ventilation sometimes associated with it.

LESS GROSS RADIOLOGICAL CHANGES

In some patients the degree of emphysema is perhaps not severe enough to give the full classical radiologieal picture, but is nevertheless abnormal. The x-ray diagnosis may be less certain, and the x-ray appearances might be graded as 'possible slight emphysema'. In one such case (Fig. 12) the diaphragm was low (7th rib) and flat, the hilar vessels perhaps a little large, but the lung vessels were not unduly small, and were within normal

limits. There were several incidents of congestive heart failure before he died. At post-mortem only a moderate degree of emphysema was found, Grade III in the upper and lower lobe, but only Grade I in the middle lobe (Reid and Millard 1964).

The incidence of the x-ray appearances of 'pos- sible slight emphysema' is low compared with the classical emphysema pattern (Table 4).

Not to be confused with the x-ray appearance of 'possible slight emphysema' is an inconspicuous though full emphysema pattern seen ~n certain patients with severe emphysema when the contrast in the radiograph is rather poor either because the excess of air in the lungs is not very great, or because of technical faults in the radiography or processing of the film. In such circumstances there is a tendency to overestimate the vessel size which may then be considered normal.

In one such case the radiograph showed the diaphragm to be only moderately low (6th rib) and not flat. The heart was 10.5 cm., narrow and vertical. The right hilum was normal though the descending artery was large. A superficial glance suggested the lung vessels were normal, but a more careful scrutiny showed that they were small except for some branches of the right descending artery which were dilated suggesting blood diversion

R A D I O L O G Y A N D E M P H Y S E M A 303

FIG. 12 FXG. 13 FIG. 12--Emphysema-- 'possible slight'. Male aged forty-seven. Thirteen years cough, sputum and increasing dyspnoea. Low flat diaphragm. Heart l l . 3 c m . Large hilar but normal mid-lung vessels. At post-mortem only Grade llI (moderate) emphysema found. Fio. 13--Chronic bronchitis, slight emphysema and pulmonary hypertension. Female aged fifty-five. Cough, sputum and increasing dyspnoea. Diaphragm low but not flat. Heart 10 cm. Large pulmonary artery and proximal hilar artery, but rest of hilar and mid-lung arteries are small. Later heart and pulmonary artery much larger with lung unchanged. At post-

mortem, right ventricular hypertrophy, but only moderate emphysema and slight arteriolar narrowings.

to this area. This all adds up to a definite emphy- sema patter n .

By contrast another patient, also suffering from chronic bronchitis, of the same age and with a superficially similar radiograph, did not qualify for the diagnosis of emphysema since the lung vessels were definitely normal. The respiratory function studies of these two patients were almost identical (Table 8), but whereas the patient showing the inconspicuous but definite emphysema pattern soon suffered from severe dyspnoea, the other patient with the more normal radiograph showed little disability for the next thirteen years, after which he developed polycythaemia and had two episodes of congestive failure, from both of which he made a good recovery.

T H E DEVELOPMENT OF EMPHYSEMA

There is still doubt concerning the development of emphysema, whether it arises as a complica- tion of chronic bronchitis or is idiopathic.

Patients with widespread emphysema complica- ting chronic bronchitis may have a history of cough, sputum and dyspnoea for as long as twenty years or, as short as two years. Moreover, only

TABLE 8

RESPIRATORY FUNCTION STUDIES OF A PATIENT WITH EMPHYSEMA PATTERN, AND OF A PATIENT WITH SIMILAR SYMPTOMS BUT A

NORMAL RADIOGRAPH

Predicted P . G . , male, age B., male, age normal values forty-one forty

4500

3750

15ml. /mm. Hg./min.

X-ray-- 'emphysema pattern'

F.V.C.--2266

F.E.V.i--680 (26 700)

Dco--8-4

X-ray--normal

V.C.--1500

F.E.V.i--520

Dco--7"7

about one-third of patients with chronic bronchitis, even when this has been present for twenty years or more, develop gross emphysema.

The emphysema pattern is commonly first seen between the ages of forty-five to sixty years, and is rarely seen in a younger person or over the age of seventy. It has been very difficult to determine the age of onset of the classical changes such as those illustrated in Figure 5. In over 200 cases with the 'emphysema pattern' an initial normal radiograph has only been available in one. This patient was

304 C L I N I C A L R A D I O L O G Y

twenty-one years old when the normal chest radiograph was taken, and seven years later, at the age of twenty-eight, he showed the full 'emphy- sema pattern' (Reid and Simon 1959). At this stage some cough, sputum and dyspnoea had been present for two years. Over the next ten years the dyspnoea became very severe, yet the radiograph was unchanged except that a bulla at the right apex enlarged. This was removed with little benefit and at operation the lung appeared grossly emphy- sematous. Comparison of the mid-lung vessel size between the normal radiograph and the later one with the emphysema pattern was most unsatisfactory because the lower position of the diaphragm in the later radiograph made identification of comparable measuring points most uncertain.

The usual course of events once the emphysema pattern has been seen, is that further radiographs over the years are unchanged but the dyspnoea gets worse. It is probable that the radiographic 'emphysema pattern' only develops when the emphysema is pathologically so gross that the respiratory reserve for exercise is almost used up. Further loss of very little lung tissue, insufficient to alter the radiographic appearances, will never- theless result in a considerable increase in the dyspnoea.

In a few cases the x-ray appearances may be typical of gross emphysema and later a bulla or bullous area may enlarge, the other areas remaining unchanged.

Rather less commonly, the classical changes are present but are not very gross, while later most of the changes become more obvious. This is a transition from possible slight to gross emphysema. In one such case as the symptoms became worse the radiographic appearances also changed. The diaphragm became lower, the heart narrower and the mid-lung vessels appeared to be smaller, whereas the hilar vessels were much the same. Definite bullae were now seen, and at post-mortem gross widespread emphysema was found.

CONDITIONS SIMULATING EMPHYSEMA CLINICALLY

There are many patients with severe dyspnoea and evidence of irreversible airways obstruction with a poor Dco who nevertheless have a normal chest radiograph. The condition may be due to bronchospasm, bronchial mucosal oedema or airway obstruction from an excess of mucus in the more peripheral airways, and yet with little or no emphysema at post-mortem. Such cases have been described in detail by Simpson, Heard and Laws

(1963). Although the prognosis for such patients may be better than for a patient with the emphy. sema pattern, they may develop cor pulmonale with failure which may be fatal. This complication seems to occur more commonly in patients with chronic bronchitis and insignificant emphysema than in those with gross emphysema (Fletcher et al 1963). Many of these patients come into hospital for the first time, usually in winter, with severe dyspnoea, cyanosis a rd mental confusion, the epsiode being apparently triggered off by an acute upper respiratory tract infection. A radiograph may show a large heart shadow and large hilar and lung vessels, and may be indistinguishable from the radiograph of the case of emphysema in heart failure (Fig. 11A). It will differ from the case of emphysema in that a previous radiograph if avail- able, or one after the patient has recovered t~rom the heart failure, will either be normal, or in the case of the later radiograph may show no more than some residual cardiac enlargement. One such patient, who died after a further incident of heart failure, had a normal radiograph except for a rather large left hilum due to dilatation of the descending branch of the pulmonary artery, both before and after the first incident of failure. At post-mortem there was little emphysema, but the left descending artery was much dilated, and contained a large thrombus with a channel running past it, thus accounting for the x-ray appearances.

Why these particular patients with chronic bronchitis as a result of a mild upper respiratory or lung infection suddenly go into heart failure is not known for certain, but the infection may lead to multiple bronchial or bronchiolar occlusions with plugs of infected mucous with consequent anoxia. Recovery is not uncommon, and such a patient may survive several years with several such incidents of heart failure, whereas patients in my series with gross emphysema rarely survived two such incidents.

Finally, there are a group of patients with asthma of late onset which may be a complication of or be complicated by chronic bronchitis. Such a patient may have considerable dyspnoea partly from the asthma and partly from the chronic bronchitis, and may also have a normal radiograph. The breathing difficulties may respond well to steroids, which would not be the case with gross emphysema.

CONDITIONS SIMULATING EMPHYSEMA RADIOGRAPHICALLY

If a normal radiograph on the whole excludes gross emphysema, it is worth considering certain

R A D I O L O G Y A N D E M P H Y S E M A , 305

conditions which might mimic the emphysema pattern. One such condition is primary pulmonary hypertension, a condition in which the main trunk of the pulmonary artery is large, the hilar vessels are large, and the lung vessels may appear small. It will differ from emphysema in that there will be no evidence of air trapping, so that the diaphragm will appear normal, while the heart shadow is enlarged and not narrow and vertical.

There is a particular group of patients, com- monly women between the ages of forty to fifty-five years, who have a combination of mild emphysema and severe pulmonary hypertension. An example is shown in Figure 13. She was fifty-five years old, and had had a cough with mucoid sputum for five years and lately increasing dyspnoea. An E.C.G. showed evidence of right ventricular hypertrophy. The dyspnoea got worse and she developed central cyanosis, while respiratory function tests gave results indicating airway obstruction, and the Dco was 6"9 (steady state). The low but not flat diaphragm, the heart of only 10 cm., and the large proximal but small distal hilar and lung vessels suggested pulmonary hypertension with no more than 'possible slight emphysema'. Just before she died the heart and main pulmonary artery showed much enlargement. At post-mortem there was indeed some emphysema, considerable right

ventricular hypertrophy, and a few thrombosed smaller pulmonary arteries, but neither the emphy- sema nor the amount of vessel loss were sufficient to account for the right ventricular hypertrophy. Presumably there was a functional vasoconstrictive element responsible for the pulmonary hyper- tension and some of the x-ray appearances.

Occasionally a case of asthma without emphy- sema may show both clinical and radiological evidence of pulmonary hypertension and if the diaphragm happens to be low and flat the x-ray appearances will simulate emphysema with cor pulmonale.

Uncomplicated asthma may also on occasion simulate emphysema, but this is uncommon. In a series of asthmatic patients (Livingstone et al 1961) who were sufficiently disabled by the asthma to require steroids, the chest radiographs were reviewed and were quite normal in the majority of cases. In some, the diaphragm was low and flat, the heart narrow and vertical and the hilar vessels were prominent (Fig. 14), but unlike the emphysema pattern, the intrapulmonary vessels were of normal s ize and not narrow. The particular patient illustrated in Figure 14 died quite soon after the radiograph was taken from status asthmaticus and at post-mortem there was no evidence Of emphy- sema. Gough (1955) also reported a series of

FIG. 14 FIo. 15 FIG. 14- -Asthma simulating emphysema pattern. Female aged thirty-nine. Periodic attacks asthma two years. Diaphragm low and flat. Heart 9.5 cm. Conspicuous though perhaps not large hilar and normal lung vessels. Died status. At post-mortem, mucous plugs in bronchioli and no emphysema. F ~ . 15--Chronic bronchitis, localised bronchiectasis complicated by poly- cythaemia. Female aged twenty-nine. Cough, sputum, severe dyspnoea~ Hb. 144 per cent (21 G.), P.C.V. 72 per cent. Large

heart, pulmonary artery and hilar vessels, otherwise normal.

306

similar cases dying in status asthmaticus, with no pathological evidence of emphysema.

A proper knowledge of the clinical state of the patient, who suffers from periodic attacks of wheezing with no sputum in the intervals will serve to distinguish uncomplicated asthma from chronic bronchitis with emphysema. Patients with the latter condition tend to have a more constant period of sputum production, particularly in winter. Some patients with asthma may of course develop chronic bronchitis in addition, which in its turn may lead on to general emphysema and thus to an emphysema pattern in the radiograph. This complication is also particularly likely to occur in those asthmatics with sensitivity to Aspergilli or some other allergen producing attacks of con- solidation and peripheral blood eosinophilia.

C H R O N I C BRONCHITIS , EMPHYSEMA A N D P O L Y C Y T H A E M I A

There are some patients with chronic bronchitis who start with a normal radiograph, and after many years develop polycythaemia (Chamberlain and Millard 1963). The radiograph will often show enlargement of the hilar vessels, and perhaps of

CLINICAL, RADIOLOGY

the heart shadow (Fig. 15), but unlike emphysema, there is no narrowing of the lung vessels, or bullae. In some of these patients there may also be a localised area of bronchiectasis.

Polycythaemia may also be a complication of gross widespread emphysema, and then the classical emphysema pattern will be seen with particularly large hilar vessels, and often large lobar and seg- mental arteries well out into the lung field (Fig. 16).

CONCLUSIONS

The radiological emphysema pattern appears to be a reliable indication of severe widespread emphysema and carries a poor prognosis.

With careful attention to the clinical aspects, a normal radiograph will almost exclude gross widespread pan-acinar emphysema with air trapping.

Clinically a patient with cough, sputum and dyspnoea f rom chronic bronchitis may be indis- tinguishable f rom a similar patient with cOmplica- ting emphysema. In uncomplicated chronic bronchitis, as long as the radiograph is normal the outlook is quite good, but an enlarging heart shadow and hilar vessel shadows, usually heralded by the onset of oedema, cyanosis, etc., or by polycythaemia, are almost as grave a finding as the emphysema pattern.

SUMMARY

Criteria for the x-ray diagnosis of gross wide- spread emphysema with air trapping are put forward, and the variations of x-ray appearances which fulfil these criteria are described.

The reliability and prognostic value of the x-ray findings are discussed.

FIG. 16 Emphysema complicated by polycythaemia. Male aged fifty-nine. Cough, sputum and increasing dyspnoea. In failure. Six years ago classical emphysema pattern. Now heart larger, hilar vessels and some lung vessels larger. Hb. 22 G, P.C.V. 64 per cent. Emphysema was Grade lII to IV.

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