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Benign metastasizing leiomyomas are benign disseminated extra-uterine tumors in patients with prior history of uterine leiomyomas and may occur years after hysterectomy. The lung is mostly affected, with less common occurrence in the brain, heart, spine, retroperitoneum, and bone. The authors present the role of

The Currarino syndrome is characterized by 3 main features: anorectal malformation, presacral lesion, and dysgenesis of the sacrum and coccyx. The presacral lesion is usually benign with a rare occurrence of malignant degeneration. The author presents 2 cases of Currarino syndrome with presacral mucinous adenocarcinoma and neuroendocrine tumor depicted by 18F FDG PET/CT.

The author presents 3 incidental cases of glomangiopericytoma exhibiting avidity of 99mTc-MIBI, 18F-FDG, and 11C-choline, respectively, during SPECT/CT evaluation of hyperparathyroidism, and PET/CT monitoring of metastatic melanoma and biochemical recurrence of prostate cancer. All the 3 cases show similar functional and anatomic features of tracer-avid lesion in the right nasal cavity from histologically proven glomangiopericytoma.

18F-FDG PET/CT is an established imaging modality for gastrointestinal stromal tumor evaluation and its posttherapeutic monitoring. 68Ga-PSMA has been recently reported with the incidental demonstration of this neoplasm on PET/CT. The author presents an uncommon case of this tumor detected by 11C-choline during the assessment of prostate cancer.

Cholecystokinin cholescintigraphy is used clinically to quantify gallbladder ejection fraction as an indicator of functional gallbladder disorder. It can also provide the opportunity to quantify an individual's responsiveness to the physiologic stimulant of gallbladder contraction, cholecystokinin, which is a major regulator of appetite and postprandial satiety. Methods: In the current work, we use cholecystokinin cholescintigraphy to quantify the kinetics of gallbladder emptying, including average and peak rates, in response to a standard cholecystokinin infusion. Results: We demonstrated that patients with no gallstones or biliary obstruction who empty their gallbladders completely in response to cholecystokinin, having an ejection fraction greater than 80%, exhibit a broad range of sensitivity to this hormone. Three distinct kinetic profiles were observed, with those most sensitive to cholecystokinin achieving the earliest peak and the fastest rate of gallbladder emptying, whereas those least sensitive to cholecystokinin have the latest peak and the slowest rate of emptying. Conclusion: Patients can have abnormal cholecystokinin stimulus-activity coupling as an effect of endogenous negative allosteric modulation by membrane cholesterol. This was predicted in ex vivo studies but has not, to our knowledge, previously been demonstrated in vivo. This type of kinetic analysis provides a tool to quantify cholecystokinin responsiveness in patients and identify patients who might benefit from a drug that would positively modulate cholecystokinin action to improve their appetite regulation and to better control their weight.

Histiocytosis is a rare inflammatory process characterized by pathologic infiltration and accumulation of cells derived from the monocytic lineage in normal tissue. It encompasses more than 100 different subtypes of disorders that were recently classified into five main groups: (a) Langerhans-related histiocytosis, (b) Rosai-Dorfman histiocytosis, (c) cutaneous and mucocutaneous histiocytosis, (d) malignant histiocytosis, and (e) hemophagocytic lymphohistiocytosis and macrophage activation syndrome. Langerhans cell histiocytosis is the most common histiocytic disorder. Less common types include Erdheim-Chester disease, Rosai-Dorfman disease, adult and juvenile xanthogranuloma, necrobiotic xanthogranuloma, histiocytic sarcoma, interdigitating dendritic cell sarcoma, Langerhans cell sarcoma, and hemophagocytic lymphohistiocytosis. Although the pathogenesis of these disorders may be attributable to mutations in the oncogenic driver, recent discoveries have shown that inflammation and fibrosis secondary to mutated histiocytes, rather than a proliferative cell mechanism, result in manifestation of the disease. Diagnosis, which relies on a multidisciplinary approach, is challenging and often delayed because clinical findings are nonspecific and may mimic malignant processes at radiologic evaluation. Compared with conventional imaging, PET/CT allows detection of the increased metabolic activity in histiocytes. Diagnostic algorithms for histiocytic disorders should include functional imaging with fluorine 18 (18F) fluorodeoxyglucose (FDG) PET/CT, which provides a comprehensive whole-body evaluation of their potential involvement with multiple organ systems and allows monitoring of therapeutic response. The most recent revised classification, pathophysiologic and clinical manifestations, sites of involvement, and imaging features of histiocytosis are described in this review and a multimodality approach is used, with emphasis on 18F-FDG PET/CT evaluation. ©RSNA, 2021.

Purpose This report describes the long-term outcomes of a prospective trial of intensity modulated radiation therapy (IMRT), integrating a 111 In capromab pendetide (ProstaScint) scan-directed simultaneous integrated boost (SIB) for localized prostate cancer. Methods and Materials Seventy-one patients with T1N0M0 to T4N0M0 prostate cancer were enrolled, and their ProstaScint and pelvic computed tomography scans were coregistered for treatment planning. The entire prostate received 75.6 Gy in 42 fractions with IMRT, whereas regions of increased uptake on ProstaScint scans received 82 Gy as an SIB. Patients with intermediate- and high-risk disease also received 6 months and 12 months of adjuvant hormonal therapy, respectively. Results The study enrolled 31 low-, 30 intermediate-, and 10 high-risk patients. The median follow-up was 120 months (range, 24-150 months). The 10-year biochemical control rates were 85% for the entire cohort and 84%, 84%, and 90% for patients with low-, intermediate-, and high-risk disease, respectively. The 10-year survival rate of the entire cohort was 69%. Pretreatment prostate-specific antigen level >10 ng/mL and boost volume of >10% of the prostate volume were significantly associated with poorer biochemical control and survival. The outcomes were compared with those of a cohort of 302 patients treated similarly but without the SIB and followed up for a median of 91 months (range, 6-138 months). The 5- and 10-year biochemical control rates were 86% and 61%, respectively, in patients without the SIB compared with 94% and 85%, respectively, in patients in this trial who received the SIB ( P =.02). The cohort that received an SIB did not have increased toxicity. Conclusions The described IMRT strategy, integrating multiple imaging modalities to administer 75.6 Gy to the entire prostate with a boost dose of 82 Gy, was feasible. The addition of the SIB was associated with greater biochemical control but not toxicity. Modern imaging technology can be used to locally intensify the dose to tumors and spare normal tissues, producing very favorable long-term biochemical disease control.

Modifications of the biodistribution of 99mTC sestamibi during the myocardial perfusion and parathyroid imaging may be secondary to benign or malignant processes of visualized anatomic structures not related to the target organs of these imaging procedures. The author presents a case of pancreatic adenocarcinoma indirectly depicted on parathyroid scintigraphy.

Uncommon penile metastasis from prostate cancer has been reported on PET/CT imaging with F-FDG, F-fluorocholine, C-choline, and Ga-PSMA. The author presents an additional case of F-fluciclovine PET/CT depiction of proximal and distal cavernosal metastases from prostate cancer with corresponding contrast-enhanced CT findings.

18F-Fluciclovine is used in the PET/CT evaluation of prostatic cancer recurrence, with 11C-Choline and 68Ga-PSMA as alternative choices of radiotracers. 18F-Fluciclovine has been reported with incidental PET/CT imaging of recurrent pancreatic adenocarcinoma and nodal metastasis from penile squamous cell carcinoma. To these PET/CT depictions of non-prostatic neoplasms, the authors add a case of urothelial carcinoma demonstrated during a routine 18F-Fluciclovine PET/CT assessment of prostatic malignancy.

Focal nodular fat sparing of the liver may show, on PET/CT imaging, prominent tracer uptake over a background of less metabolic features of steatosis. This finding, already reported with F-FDG, may mimic primary or secondary neoplasms of the liver. The authors present an additional case of nodular fat-sparing hepatic parenchyma exhibiting C-choline avidity during PET/CT assessment for biochemical recurrence of prostate cancer.

Trichoblastic carcinoma is an uncommon malignant neoplasm arising from follicular germinative cells. The high-grade trichoblastic carcinoma has been reported with lymphatic and hematogenous dissemination. The authors present a 59-year-old man with gluteal cleft trichoblastic carcinoma and highlight the useful role of serial F-FDG PET/CT examinations in the demonstration of initial and subsequent nodal metastasis in the inguina and pelvis.

We present serial bone scintigraphy examinations in a 38-year-old woman who presented with posterior left rib pain in the setting of adrenal insufficiency secondary to pituitary damage as a result of radiation treatment for orbital sarcoma.

Our objective was to define the role of combined (99m)Tc-sulfur colloid bone marrow (SC BM) scintigraphy, SPECT or SPECT/CT, and chest CT in diagnosing diffuse pulmonary extramedullary hematopoiesis (PEMH) in patients with myelofibrosis. Methods: We retrospectively reviewed (99m)Tc-SC BM scintigraphy scans performed at our institution for the diagnosis of diffuse PEMH, as well as accompanying chest CT and SPECT/CT imaging findings. Relevant clinical information, including respiratory manifestations, pulmonary hypertension, and subjective response to whole-lung radiation therapy, was also summarized. Results: Twenty-two myelofibrosis patients with 27 (99m)Tc-SC BM scintigraphy scans were diagnosed with diffuse PEMH. In 21 patients (95%) with accompanying chest CT and SPECT/CT scans, the most common CT findings were ground-glass opacity, interstitial infiltration, and pleural effusion. Of 20 patients (91%) who underwent 2-dimensional echocardiography studies, 12 (55%) were diagnosed with pulmonary hypertension. All 12 patients exhibited the aforementioned nonspecific CT imaging findings, with 8 (66%) of them presenting with respiratory symptoms, including dyspnea, shortness of breath, and cough. In the remaining 8 patients, without pulmonary hypertension, half had similar respiratory symptoms. Fourteen patients (64%) of this cohort received whole-lung radiation therapy, of whom 7 (50%) experienced symptom relief after therapy. Conclusion: Nonspecific respiratory symptoms should raise concern about pulmonary hypertension and diffuse PEMH in patients with advanced-stage myelofibrosis. Combined (99m)Tc-SC BM scintigraphy and SPECT/CT is a promising noninvasive imaging tool to diagnose this rare clinical entity. Key Words: hematology; respiratory; SPECT/CT; pulmonary hematopoiesis; Tc-99m sulfur colloid scintigraphy; myelofibrosis

Nuclear stress testing is being increasingly justified in the cardiovascular risk stratification of patients. Radiation is an important consideration, and attempts to minimize exposure should be implemented. Efficiency and cost effectiveness are cornerstones in the delivery of quality patient care and should also be considered when implementing change. Methods: We studied 88 consecutive patients who presented to our stress lab for pharmacologic nuclear stress testing. A single-day rest-and-stress protocol with low-level exercise was used for all patients. After the stress portion of the examination, we measured Geiger counter activity above the bladder area to establish a baseline. Patients were then allowed to void, and repeat measurements were taken. Results: We detected a 16.9% reduction from baseline radiation levels above the bladder area after voiding. Conclusion: Urinary voiding is a simple, cost-effective strategy at reducing radiation exposure in the nuclear stress lab.

Tumor induced osteomalacia (TIO) is a rare paraneoplastic syndrome caused by overproduction of fibroblast growth factor 23 (FGF23) secreted by benign mesenchymal neoplasm. Due to its nonspecific clinical presentation or lack of awareness, the diagnosis of TIO is often significantly delayed resulting in patients' prolonged physical suffering or psychological distress. Successful detection or complete surgical resection of the causative tumor typically leads to rapid resolution of symptoms or reversal of biochemical imbalance. Nuclear medicine and molecular imaging have been playing a promising role as the first-line imaging modalities in the diagnosis and localization of occult FGF23 secreting mesenchymal tumor, especially with the emerging whole-body, head-to-toe Ga68-DOTATATE PET/CT technique. Combined focused diagnostic CT and/or MRI are imperative for accurate delineation of tumor and surgical guidance.

Advance awareness of the renal vascular anatomy, including variants of the left renal vein, is important for abdominal and renal surgery. The migratory nature ofrenal embryology and significant transformation of precursors of the inferior vena cava and renal veins can make the final configuration of these structures complex. Two uncommon instances of dual left renal vein with orthotopic left common iliac vein and ectopic caval drainage are presented with multi-detector CT imaging.

Furosemide may trigger life-threatening sulfonamide cross-hypersensitivity reactions, posing a dilemma in patients who need diuretic renal scintigraphy. Methods: We present our experience using ethacrynic acid as a nonsulfonamide alternative diuretic in 5 patients, with a discussion of the diuretic molecular structure, potential side effects, protocol development, and imaging results. Results: Diuretic renal scintigraphy using ethacrynic acid provided useful information about the obstruction status in all patients, with no adverse clinical impact. Conclusion: Ethacrynic acid is a potential alternative to furosemide for patients with severe sulfonamide reactions.

Mesothelioma is a malignancy arising from the embryonic coelomic mesodermal lining forming the pleura, peritoneum, pericardium, and tunica vaginalis. It is mostly induced by exposure to asbestos. The author presents a 77-year-old woman with an atypical manifestation of epithelioid mesothelioma, which does not follow the expected clinical characteristics of this disease mentioned above. In this case, PET/CT provides useful information concerning the extension of the lesions to thoracic and abdominal walls not fully evaluated by the initial conventional cross-sectional imaging. PET/CT also allows an accurate therapeutic monitoring of the disease.

A middle-aged patient with known neurofibromatosis type 1 (NF1) presented with an increase in the size and number of cutaneous lesions. The lesions were further evaluated with positron emission tomography (PET)/CT that showed diffuse hypermetabolic neurofibromas of the neck, thorax, proximal lower extremities (figure 1) and a fluorodeoxyglucose (FDG)-avid lesion in the left lower abdominal quadrant. Biopsy of the FDG-avid lesions on the left shoulder and right thigh were histologically consistent with …

Clear cell adenocarcinoma of the urethra is a rare and aggressive tumor of female gender preponderance. This neoplasm, the origin of which is still widely debated, has been reported with CT and MRI in case reports and small series. To the previously published conventional cross-sectional imaging description, the authors add the PET/CT features of this uncommon urologic neoplasm at its advanced stage in a 60-year-old patient complaining of urinary retention.

Malignant peritoneal mesothelioma is usually confined to the abdomen and pelvis. Extra-abdominal and extrapelvic dissemination is very uncommon mostly at advanced stages of the disease. This rare clinical event may be related to contiguous spread through connecting pathways linking the abdomen and pelvis to the thorax and proximal lower extremity. The authors present a case of advanced malignant peritoneal mesothelioma with contiguous dissemination to the right thigh and proximal leg documented and monitored by F-FDG PET/CT imaging.

Acute aortic syndromes, encompassing intramural hematoma, penetrating ulcer, and pseudoaneurysm, are best demonstrated by angiographic CT and magnetic resonance imaging. These imaging modalities provide an accurate evaluation and allow timely therapies of these frequently symptomatic lesions, thus reducing their morbidity and mortality. The inflammatory pathogenesis of these acute aortic syndromes may exhibit positive PET findings predictive of prognosis and outcomes of these vascular events. The authors present a case of PET/CT imaging showing asymptomatic intramural hematomas with penetrating ulcer and saccular pseudoaneurysm of the proximal abdominal aorta.