Abstract A 52-year-old woman underwent [ 99 m Tc]Tc-hydroxydiphosphonate ([ 99 m Tc]Tc-HDP) bone scintigraphy for evaluation of lower back pain. Whole-body imaging incidentally revealed intense uptake in the left orbital region, which was absent on a previous scintigraphy 8 years earlier. Skull single-photon emission computed tomography/computed tomography (SPECT/CT) proved to be essential in this setting, localizing the abnormal uptake to a hyperostotic reaction involving the greater wing of the sphenoid, with a characteristic spiculated appearance. These findings were highly suggestive of a spheno-orbital en plaque meningioma. Contrast-enhanced MRI demonstrated plaque-like dural thickening underlying the hyperostotic reaction, supporting the radiological diagnosis. The intense [ 99 m Tc]Tc-HDP uptake most likely reflected active osteoblastic/hyperostotic bone remodeling rather than uptake by the soft tissue tumor itself. This case illustrates the added value of SPECT/CT for localizing and characterizing unexpected skull-base uptake detected on planar bone scintigraphy. Conservative management with radiological follow-up was adopted.
Abstract Pleomorphic sarcoma is an aggressive soft-tissue malignancy with heterogeneous metabolic characteristics and tumor biology. We herein report a 52-year-old woman with metastatic high-grade pleomorphic sarcoma who underwent dual-tracer imaging with [ 18 F]Fluorodeoxyglucose and [ 68 Ga]Ga-Fibroblast activation protein inhibitor (FAPI-04) Positron emission tomography/computed tomography (PET/CT) during disease surveillance. Despite histologically high-grade disease, metastatic lesions demonstrated only low-grade FDG uptake, whereas [ 68 Ga]Ga-FAPI-04 PET/CT showed intense tracer accumulation with markedly superior lesion conspicuity. On subsequent restaging, [ 68 Ga]Ga-FAPI-04 PET/CT more accurately delineated progression of pleural disease and identified additional metastatic sites involving the brain, tongue, and contralateral thigh. This case illustrates the unusual ambiguity between histological grade and glucose metabolism, with a high-grade pleomorphic sarcoma showing low FDG avidity. The case highlights the biological heterogeneity of sarcoma, the limitations of FDG PET/CT in selected patients, and the complementary diagnostic and theranostic potential of FAPI PET/CT in high-grade pleomorphic sarcoma. The high FAPI uptake observed across all lesions suggested the potential feasibility of fibroblast activation protein (FAP)-targeted radioligand therapy, expanding the role of FAPI in the theranostic management of sarcoma.
Abstract Background Ectopic insulinomas are rare tumors and difficult to diagnose with conventional imaging. We report a case of multifocal duodenal neuroendocrine tumor (NET) along with a functional insulin-secreting duodenal lesion diagnosed with dual-tracer positron emission tomography/computed tomography (PET/CT) imaging in a case of endogenous hyperinsulinism. Case Presentation A 72-year-old man presented with a 2-week history of recurrent hypoglycemia, which showed improvement with intravenous glucose infusion. His 72-hour fasting test confirmed endogenous hyperinsulinism with elevated fasting serum insulin and C-peptide levels. A CT scan revealed a polypoidal soft tissue mass in the posterolateral wall of the urinary bladder. Since nonislet cell tumors are a rare cause of endogenous hyperinsulinism due to ectopic insulin secretion or insulin-like growth factor 2 production, the bladder mass was initially suspected as the cause of hypoglycemia. The patient was referred for [ 68 Ga]-Ga-exendin-4 PET/CT to rule out insulinoma, which showed multiple duodenal lesions with a single glucagon-like peptide-1 receptor expressing duodenal lesion as the possible insulin-secreting source and excluded the bladder lesion as the culprit. He also underwent [ 68 Ga]Ga-DOTATATE PET/CT, which revealed somatostatin receptor (SSTR) expression in the multiple duodenal lesions. The patient underwent excision of multiple duodenal lesions. There was partial resolution of hypoglycemia postsurgery with fasting blood glucose rising from 40 to 50 mg/dL preoperatively to 60 to 70 mg/dL. Conclusion [ 68 Ga]Ga-exendin-4 and [ 68 Ga]Ga-SSTR PET/CT were useful in establishing a diagnosis of multifocal duodenal NET with detection of all lesions along with localization of functional components in this patient, therefore assessing functional heterogeneity in a multifocal NET in a case of endogenous hyperinsulinism.
Abstract Adrenal involvement in non-Hodgkin lymphoma is uncommon and is recognized as a marker of adverse outcomes and of tropism for the central nervous system (CNS). We report a 22-year-old man who presented with fever, weight loss, and abdominal pain, in whom whole-body 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) demonstrated a large FDG-avid right suprarenal mass with contralateral adrenal involvement, 10 metabolically active cerebral lesions with mass effect, and FDG-avid deposits in the right atrium and left ventricle, together with peritoneal, soft tissue, and osseous disease. Biopsy of a retroperitoneal lymph node confirmed aggressive B-cell non-Hodgkin lymphoma. Imaging raised the enumerated extranodal count from two to at least six, establishing Ann Arbor stage IVB disease with an International Prognostic Index (IPI) of 4 and a CNS-IPI of 5. The patient died before treatment could be initiated. To our knowledge, this is the first imaging documentation of synchronous adrenal, cardiac, and CNS involvement in aggressive B-cell lymphoma.
Abstract Blood-pool single-photon emission computed tomography (SPECT)/CT demonstrated marked focal hyperemia localized to the right medial cuneiform, with suspicion of an underlying bipartite variant, a finding not present on the left side. This blood-pool positivity is critically important: it directly demonstrates active vascular permeability and synovitis-like inflammation at the pseudoarticulation cleft, a pathophysiological layer that neither CT nor magnetic resonance imaging can provide under physiological weight-bearing conditions. Without the blood-pool phase, the inflammatory component of the synchondrosis activity would have remained entirely undetected.
