Radiomics for differentiation of the posterior fossa pilocytic astrocytoma versus hemangioblastomas in adults. A pilot study.

PURPOSE: Both pilocytic astrocytoma (PA) and hemangioblastoma (HB) are common primary neoplasms of the posterior fossa with similar radiological manifestations. This study was conducted to evaluate the role of Radiomics in differentiating these two conditions in adults. MATERIALS AND METHODS: After a retrospective search of our institutional imaging archive, adult patients with a known diagnosis of PA or HB were included. We reviewed each patient's most recent preoperative brain magnetic resonance imaging (MRI). The solid enhancing nodule of each lesion on post-contrast T1 sequence was manually segmented. Multiple Radiomics features were then extracted from each nodule using the Pyradiomics library. Subsequently, the most predictive features were identified by feature selection models. Following this, different machine learning (ML) models were constructed based on these selected features to classify lesions as PA or HB. Finally, we evaluated the performance of each model by leave-one-out cross-validation. RESULTS: With inclusion and exclusion criteria, 34 enhancing PA nodules and 39 HB nodules were selected. A total of 115 features were extracted from each enhancing nodule. Twelve characteristics were detected as most predictive of histopathological diagnosis. Among various ML models, the neural network had the best performance in differentiating these two conditions with an AUC of 0.9 and an accuracy of 82%. CONCLUSIONS: In this retrospective study, Radiomics MRI techniques demonstrated high performance in distinguishing adult posterior fossa PA from HB. Future development of Radiomics models may advance presurgical diagnosis of these two conditions when added to routine clinical practice and thus improve patient management.

Ultrasound has limited diagnostic utility in children with acute lymphoblastic leukemia developing pancreatitis.

PURPOSE: Acute pancreatitis (AP) due to chemotherapy-induced pancreatic injury is a common side effect of treatment for acute lymphoblastic leukemia (ALL), the most common childhood malignancy. The American College of Radiology recommends ultrasound (US) for initial imaging of AP in all populations to assess for ductal obstruction. However, US may be insensitive to diagnose and assess chemotherapy-associated AP. METHODS AND MATERIALS: The institutional review board approved this retrospective study. Patients with ALL and AP were identified from protocol databases, using Common Terminology Criteria for Adverse Events (CTCAE) version 3. Chemotherapy dosing, amylase/lipase levels, clinical symptoms, and US/computed tomography (CT) reports within 10 days of diagnosis were recorded. All CT images were reviewed for revised Atlanta classification and CT severity index (CTSI). RESULTS: Sixty-nine patients, aged 2-21 years, experienced 88 episodes of AP, undergoing 98 US and 44 CT. Seventy-two events (82%) occurred within 30 days of asparaginase administration. Sixty-nine episodes (78%) were initially diagnosed by the presence of abdominal pain and pancreatic enzyme elevation. Overall sensitivities for AP detection were 47% using US and 98% for CT. US sensitivity was greatest in CTCAE grade 4 (86%) and necrotizing pancreatitis (67%). CONCLUSIONS: Most cases of AP in children with ALL can be diagnosed with clinical history and labs. US has limited sensitivity in detecting pancreatitis in this population. Imaging to diagnose AP in this patient population could be limited to clinically equivocal cases.