B-cell peripheral neurolymphomatosis: MRI and 18F-FDG PET/CT imaging characteristics.

OBJECTIVE: To examine the MRI and 18F-FDG PET/CT imaging characteristics of peripheral neurolymphomatosis. MATERIALS AND METHODS: All institutional cases of neurolymphomatosis with an MRI or 18F-FDG PET/CT from 2000 to 2017 were retrospectively reviewed. Included cases were biopsy-proven neurolymphomatosis or lymphoma patients with clinical and imaging evidence of neurolymphomatosis that resolved after chemotherapy. Multiple imaging parameters and clinical characteristics were recorded. RESULTS: There were 27 cases of B-cell neurolymphomatosis in 25 patients (18 M, 7 F; mean age 64.6 ± 10.0 years). Of the total cases, 85% (23/27) were biopsy-proven. Most were diagnosed after disease progression or recurrence (20/27, 74%), and presented with isolated nerve involvement (18/27, 67%). Bone marrow biopsy (17/19, 89%) and CSF cytology (16/23, 70%) were usually negative. On 18F-FDG PET/CT, neurolymphomatosis presented as a linear or fusiform (23/26, 88%), FDG-avid (average SUVmax: 7.1 ± 4.5, range, 1.5-17.0) mass, and on MRI as a T2-weighted hyperintense (21/22, 95%), enhancing (21/22, 95%), linear or fusiform mass (19/22, 86%), with associated muscle denervation (14/22, 64%). FDG avidity was significantly higher in patients with muscular denervation on MRI (mean SUVmax 8.2 ± 4.6 vs. 4.3 ± 2.3, p = 0.04). CONCLUSIONS: B-cell neurolymphomatosis most commonly manifests as T2-weighted hyperintense, enhancing linear or fusiform neural enlargement associated with muscular denervation on MRI, with intense FDG activity on PET/CT. It is most often an isolated site of disease, presenting after progression or recurrence. A familiarity with the imaging appearance of neurolymphomatosis can help refine the differential diagnosis, direct biopsy, and aid in accurate diagnosis.

Adaptive replanning to account for lumpectomy cavity change in sequential boost after whole-breast irradiation.

PURPOSE: To evaluate the efficiency of standard image-guided radiation therapy (IGRT) to account for lumpectomy cavity (LC) variation during whole-breast irradiation (WBI) and propose an adaptive strategy to improve dosimetry if IGRT fails to address the interfraction LC variations. METHODS AND MATERIALS: Daily diagnostic-quality CT data acquired during IGRT in the boost stage using an in-room CT for 19 breast cancer patients treated with sequential boost after WBI in the prone position were retrospectively analyzed. Contours of the LC, treated breast, ipsilateral lung, and heart were generated by populating contours from planning CTs to boost fraction CTs using an auto-segmentation tool with manual editing. Three plans were generated on each fraction CT: (1) a repositioning plan by applying the original boost plan with the shift determined by IGRT; (2) an adaptive plan by modifying the original plan according to a fraction CT; and (3) a reoptimization plan by a full-scale optimization. RESULTS: Significant variations were observed in LC. The change in LC volume at the first boost fraction ranged from a 70% decrease to a 50% increase of that on the planning CT. The adaptive and reoptimization plans were comparable. Compared with the repositioning plans, the adaptive plans led to an improvement in target coverage for an increased LC case (1 of 19, 7.5% increase in planning target volume evaluation volume V95%), and breast tissue sparing for an LC decrease larger than 35% (3 of 19, 7.5% decrease in breast evaluation volume V50%; P=.008). CONCLUSION: Significant changes in LC shape and volume at the time of boost that deviate from the original plan for WBI with sequential boost can be addressed by adaptive replanning at the first boost fraction.