Establishment of normative values for the fetal posterior fossa by magnetic resonance imaging.

OBJECTIVE: Suspected Dandy-Walker continuum anomalies constitute a significant percentage of prenatal cases evaluated by magnetic resonance imaging (MRI). To unify the description of posterior fossa malformations, we sought to establish objective measurements for the posterior fossa in normal fetuses between 18 and 37 weeks gestation. METHODS: T2-weighted images of normal fetal brains in sagittal projection were obtained from fetal magnetic resonance (MR) studies of normal brains performed from 2009 to 2017.121 fetal brains were included in the analysis. Three radiologists reviewed images and recorded the following for each case: superior posterior fossa angle (SPFA), posterior fossa perimeter, and tegmento-vermian angle (TVA). RESULTS: For each feature, the mean of the measurements, the percentage of absolute difference of the reader measurement compared with mean measurement, and the interclass correlation (ICC) were calculated. Values are reported as mean ± standard deviation. Perimeter increases linearly with age, whereas the SPFA and the TVA are independent of gestational age. For all included cases, the SPFA averaged 100.9° ± 8° and the TVA averaged 2.5° ± 2.3°. CONCLUSION: The superior posterior fossa angle, a novel measurement, and the posterior fossa perimeter can be used for establishing the expected size of the posterior fossa in second- and third-trimester fetuses by MRI.

Testicular FDG Uptake on PET/CT in Patients with Lymphoma: Correlation with Age.

The purpose of this observational study was to investigate whether the standard uptake value (SUV) measurement has practical utility in distinguishing secondary testicular involvement from physiologic uptake in patients with lymphoma. A Radiology Information System (RIS) search was conducted for all PET/CT studies performed from 2010-2016 on adult male patients with a diagnosis of lymphoma. Patients with clinical or pathologic diagnosis of testicular lymphoma were excluded to undergo a separate analysis. PET/CT images of 606 patients with 1087 scans, in which 2045 testes were included in the field of view, were reviewed and measurements were performed for standardized uptake values of both testicles (SUVmax) as well as of the liver (SUVmax and SUVmean). The mean SUVmax of the testicles was 3.75 ± 0.90 (range 1.16-8.38). The mean ratio of testis SUVmax / liver SUVmean (T/L) was 1.78 ± 0.43. Trends in SUVmax and age were significant for a negative correlation by a small magnitude of 0.066 per 10 years (P < 0.001). T/L had similar changes with significant low magnitude decrease with increasing age (0.059 per 10-year increase, P < 0.001). In our separate analysis of 3 patients with clinical or pathology proven testicular lymphoma, the average pathologic SUVmax was 13.47 (range 11.39-15.97). This study has the largest known sample size for quantifying physiologic uptake in the testes. SUV measurements to quantify F-18 Fluorodeoxyglucose (FDG) uptake on PET/CT likely have practical utility in discriminating between physiologic and pathologic uptake of FDG in cases of secondary testicular lymphoma.

Spontaneous regression of a metastatic melanoma pulmonary deposit following biopsy.

Spontaneous complete and partial regression of metastatic melanoma is poorly understood, and is a rare phenomenon with less than 80 cases reported since 1866. Several correlations have been noted such as systemic or local infections, operative trauma, hormonal influences, nutrition and immunologic factors. We present FDG PET and CT findings in a patient with multiple pulmonary metastases of melanoma, one of which underwent regression following biopsy. We suggest immune system modulation, triggered by biopsy, could have played a role, although the precise mechanism remains unknown.