RECCURENT MEDULLOBLASTOMA:ROLE OF DIFFUSION WEIGHTED

IMAGING

Dr. Rakhee Gawande M.D and Dr. David Nascene M.D

Department of Radiology

Control# 1638Poster# EP 130

DISCLOSURES

• NONE

INTRODUCTION• Medulloblastoma is the most common malignant

CNS tumor of childhood

• Comprise 15-20% of CNS tumors of children

• 35-40% recurrence rate

• Surveillance imaging important for early detection,

prompt intervention and good outcome

• MRI of the brain and spine remain primary modality

for diagnosis of recurrence

• Since relapse is typically intra-cranial, surveillance

spine MRI has low yield

SURVEILLANCE IMAGING• The reported rate of asymptomatic relapse is 19-

46%

• Multiple studies have shown that surveillance

imaging detected minority of recurrences with no

survival advantage

• Survival advantage limited due to our inability to

successfully treat recurrence.

• Current treatment regimen per the COG Phase II

screening trial (ACNS0821) include combination of

temozolomide, irinotecan, and bevacizumab

SURVEILLANCE IMAGING

• In the ACNS0821, recurrence is defined as tumor

measurable in two perpendicular dimensions on

MRI and histologic verification of malignancy at

original diagnosis, but not necessarily at the time of

recurrence.

• Recurrent disease should be differentiated from

treatment-related changes like radiation necrosis or

pseudoprogression

SITES OF RECCURENT DISEASE• Relapse more common in young children• Isolated local recurrence rare; usually

associated with meningeal dissemination• Local recurrence not associated with

incomplete resection• Risk for local recurrence influenced by

patient age and not by amount of residual tumor

• Frontobasal region predominant site for supratentorial meningeal recurrence

PURPOSE

To compare the rate of detection of recurrent

disease on diffusion weighted imaging (DWI)

with contrast enhanced imaging (CE-MRI)

MATERIAL AND METHODS

• Retrospective review of MRI of patients with

medulloblastoma

• Recurrence defined as an area of hyperintense

signal on DWI with iso-hypointense signal on ADC

(Apparent diffusion coefficient)

• And area of nodular enhancement on CE-MRI

RESULTS• Database search from 2003 to 2013 revealed 45 patients

with medulloblastoma

• 12 patients (26%) suspected to have recurrent disease

• Mean age of patients at recurrence 17.1+/-14.4 yrs (range 4

to 47, median 11 yrs)

• Male: Female 8:4

• Mean time interval from diagnosis to recurrence is 36.3 +/-

32.5 months (range 6 to 113 months)

• Site of recurrence:

Cerebellum:7

Subependymal: 5

Basal cistern:1

RESULTS

COMPARISON OF DWI WITH CE-MRI:

• 9/12 patients with confirmed recurrence had

restricted diffusion signal (100%)

• Only 5/12 patients had contrast enhancement (55%)

• 2/12 patients with radiation necrosis had positive

contrast enhancement and no restricted diffusion

signal

SENSITIVITY SPECIFICITY PPV NPV

DWI 100% 75% 90% 100%

CE MRI 55.56% 33.33% 71.43% 20%

3 monthFollow up

DWI ADC Post gad

38 yr old male with local recurrence 30 months after therapy along the inferomedial right cerebellum. Note restricted diffusion signal on an initial scan without associated enhancement. A close interval follow-up showed enhancement in this region consistent with biopsy proven recurrence

LOCAL RECURRENCE

DWI ADC Post gad

8 yr old male with local recurrence in the right cerebellum seen as an area of restricted diffusion signal with associated enhancement. Note persistent disease on follow up scans

6 mthFollowup

LOCAL RECURRENCE

SUBEPENDYMAL RECURRENCE

13 yr old female with subependymal recurrence 74 months after therapy. Note enhancing nodular lesion in the midline along the septum pellucidum with restricted diffusion signal

DWI ADC Post gad

SUBEPENDYMAL RECCURENCE

DWI ADC Post gad

9 yr old female with subependymal recurrence in the frontal horn of both lateral ventricles, 34 months after therapy. Note absence of contrast enhancement with clear detection of lesion on DWI

SUBEPENDYMAL RECCURENCE

DWI Post gad

5 yr old male with subependymal recurrence seen 16 months after therapy. Note that the lesion is easily identified on DWI due to restricted diffusion signal. Lesion is not clearly apparent on post contrast images.

SUBEPENDYMAL RECCURENCE

DWI ADC Post gad

10 yr old male with subependymal recurrence 56 months after therapy. The lesion is easily identified in the anterior body of the left lateral ventricle on DWI and shows progressive increase in size and restricted diffusion signal over 1 yr period. Note lack of contrast enhancement and difficulty in detection on the post-contrast images. Lesion was missed on several scans performed at an outside facility.

RADIATION NECROSIS

6 MONTHFOLLOW UP

4 yr old female with patchy enhancement in the right cerebellum 9 months following treatment. Note absence of DWI signal abnormality. Follow up imaging showed resolution of enhancement without treatment, consistent with radiation necrosis

DWI ADC Post gad

CONCLUSION

• Restricted diffusion signal is commonly seen in

patients with recurrent medulloblastoma

• It can aid in the early detection of these lesions with

favorable outcome.

• Hence DWI images should be carefully scrutinized

in all patients and suspicious areas carefully

followed.

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