Small Cell Neuroendocrine Carcinoma of the Prostate on 18 F-DCFPyL and 18 F-FDG PET/CT.

ABSTRACT: A 51-year-old man with newly diagnosed small cell neuroendocrine carcinoma of the prostate was referred for a staging 18 F-DCFPyL PET/CT, which showed a solitary metastasis in the left acetabulum. Subsequent 18 F-FDG PET/CT showed intense uptake throughout the prostate as well as extensive avid pelvic and thoracic nodal disease and redemonstration of the left acetabular metastasis. Despite initial metabolic response to treatment, subsequent 18 F-FDG PET 8 months later revealed significant progression of nodal disease above and below the diaphragm, as well as multiple new sites of metastases.

False positive metastatic disease due to combined thoracic and subcutaneous splenosis.

A 56-year-old man presented with dyspnea secondary to pulmonary emboli and dilated cardiomyopathy. His past medical history included a history of emergency laparotomy, splenectomy, and splenic flexure resection following a gunshot injury 30 years ago. CT and MRI imaging demonstrated multiple homogeneously enhancing lobulated lesions at the left-sided pleura and chest wall with an irregular calcified spleen. The aforementioned lesions demonstrated a similar level of tracer uptake to the splenic activity with no evidence of other FDG avid malignancy on the follow-up 18F-FDG PET study. All the above-mentioned pleural and chest wall lesions demonstrated intense tracer accumulation on technetium-99m labeled heat-damaged red cell scintigraphy, consistent with combined thoracic and subcutaneous splenosis.

Diagnostic accuracy of bone scan at different PSA levels in biochemical recurrence of prostate cancer.

OBJECTIVE: To determine the diagnostic accuracy of Bone Scan at different PSA levels for detecting skeletal metastases in men with biochemical recurrence of prostate cancer. METHODS: We conducted a retrospective review of the statewide RIS-PACS to identify 251 men with biochemical recurrence who underwent both a Bone Scan and Ga68 PSMA PET/CT (within 2 months of each other) between September 2019 and December 2022 at a single institution. The Ga68 PSMA PET/CT report was considered to be the reference standard. RESULTS: The median age was 72 years (IQR 67-76) with a median PSA level of 1 ng/ml (IQR 0.25-2.8). Using Ga68 PSMA PET/CT as the reference standard, 68/251 patients (25%) were positive for osseus metastases. Overall sensitivity and specificity of Bone Scan was 51% (95% CI 40-64%) and 99% (95% CI 98-100%) respectively. Using PSA banding, a PSA threshold of 20 ng/ml provided the greatest discriminatory benefit with sensitivity of the Bone Scan below the threshold being 46% (95% CI 33-59%) and above the threshold being 89% (95% CI 68-100%). Specificity remained consistently high both below and above this threshold. CONCLUSION: Bone Scan provides greater diagnostic accuracy for detecting skeletal metastases in biochemical recurrence when the PSA level is above 20 ng/ml. This knowledge is valuable in optimising imaging algorithms in biochemical recurrence, particularly in regions where PSMA PET/CT is less readily available or affordable.

False-Positive Metastatic Bone Disease on FDG PET/CT Due to Multilevel Tophaceous Gout of the Spine.

ABSTRACT: A 74-year-old woman was referred for 18 F-FDG PET/CT for the evaluation of incidental CT finding of expansile destruction of left L4/5 facet joint with associated soft tissue mass concerning for a metastatic deposit. The FDG PET/CT revealed variable abnormally increased FDG activity involving multiple facet joints in all regions of the spine with corresponding expansile "punched-out" lytic lesions with sclerotic rims and overhanging margins on CT, raising the possibility of inflammatory polyarthropathy, including gout, as a differential diagnosis. Dual-energy CT of lumbar spine and CT-guided biopsy and culture of the left L4/5 facet joint demonstrated the presence of urate crystal deposition with no evidence of malignancy or infection, confirming the diagnosis of multilevel tophaceous gout of the spine.

Incidental Prostate-Specific Membrane Antigen-Avid Vestibular Schwannoma Detected on 68 Ga-Prostate-Specific Membrane Antigen PET/CT.

ABSTRACT: A 62-year-old man was referred for a 68 Ga-prostate-specific membrane antigen (PSMA) PET/CT scan for newly diagnosed prostate cancer (ISUP grade 5), on the background of left vestibular schwannoma treated with surgical excision 25 years ago. PSMA PET study confirmed the presence of PSMA-avid malignancy in the left prostate lobe with no evidence of PSMA-avid nodal or distant metastasis. An incidental PSMA-avid focus (SUV max , 4.3) was identified in the region of the left cerebellopontine angle, which corresponded to a homogeneous enhancing lesion centered at the left internal acoustic canal and left cerebellopontine angle on MRI. The combined PSMA PET findings and MRI characteristics were consistent with recurrent vestibular schwannoma.

Intra-individual comparison of prostate-specific membrane antigen positron emission tomography/computed tomography versus bone scan in detecting skeletal metastasis at prostate cancer diagnosis.

OBJECTIVES: To compare the diagnostic performance and radiological staging impact of 68 Ga-prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) compared to 99 Tc whole-body bone scan (WBBS) for the detection of skeletal metastasis in the primary staging of prostate cancer (PCa). PATIENTS AND METHODS: A prospective institutional database was retrospectively examined for patients who underwent both PSMA PET and WBBS within a 1 week interval for PCa primary staging. Lesions were categorised as 'negative', 'equivocal', or 'definite' based on nuclear medicine physician interpretation. Metastatic burden was characterised for each imaging modality according to three groups: (i) local disease (no skeletal metastases), (ii) oligometastatic disease (three or fewer skeletal metastases), or (iii) polymetastatic disease (more than three skeletal metastases). RESULTS: There were 667 patients included. The median (interquartile range) prostate-specific antigen level was 9.2 (6.2-16) ng/mL and 60% of patients were high risk according to a modified D'Amico risk classification. The overall distribution of skeletal metastasis detection changed across the two scans overall (P = 0.003), being maintained within high-risk (P = 0.030) and low-risk (P = 0.018) groups. PSMA PET/CT identified more definite skeletal metastases compared to WBBS overall (10.3% vs 7.3%), and according to risk grouping (high: 12% vs 9%, intermediate: 4% vs 1%). Upstaging was more common with PSMA PET/CT than WBBS (P = 0.001). The maximum standardised uptake value (SUVmax ) of the primary tumour was associated with upstaging of skeletal metastases on PSMA PET/CT (P = 0.025), while age was associated with upstaging on WBBS (P = 0.021). The SUVmax of the primary tumour and metastases were both higher according to extent of metastatic disease (P = 0.001 and P < 0.001, respectively). CONCLUSIONS: More skeletal metastases were detected with PSMA PET/CT than WBBS, resulting in a higher upstaging rate mostly in high-risk patients. The SUVmax of the primary tumour and metastases was associated with upstaging.

Gastric Schwannoma Demonstrated on 18 F FDG PET/CT With Pathological Correlation.

ABSTRACT: A 66-year-old man with background hypertension and type 2 diabetes presented with 1 month history of epigastric pain for investigation. Abdominal CT and MRI identified round homogeneously enhancing mass arising from the lesser curvature of the stomach. On 18 F-FDG PET/CT, the gastric mass demonstrated intense FDG uptake (SUV max , 9.6). The patient subsequently underwent partial gastrectomy, with pathological features and immunohistochemical patterns consistent with gastric schwannoma.

Solitary Prostate Carcinoma Penile Metastasis on 18 F-DCFPyL PET/CT.

ABSTRACT: An 83-year-old man was referred for an 18 F-DCFPyL PET scan for the evaluation of rising serum prostate-specific antigen level on the background of previous radical prostatectomy for prostate adenocarcinoma and urinary outflow tract obstruction requiring in-dwelling catheter insertion. The PET scan demonstrated focal increased activity (SUV max , 35.7) at the dorsal aspect of the mid penile shaft, with histopathological confirmation of penile metastasis from primary prostate cancer.

False-Positive Metastatic Disease Due to Bilateral Ectopic Adrenal Tissue.

ABSTRACT: A 60-year-old man was referred for staging of prostate cancer. Initial CT scan demonstrated soft tissue lesions in bilateral renal hila, which demonstrated mild 68 Ga-PSMA avidity and moderate FDG avidity on sequential PET scans suspicious for malignancy. Biopsy confirmed adrenal cortical tissue. This case highlights an exceedingly rare occurrence of ectopic adrenocortical tissue in both renal hila.

Peritoneal Carcinomatosis From Metastatic Prostate Cancer Identified on 68 Ga-Prostate-Specific Membrane Antigen PET/CT.

ABSTRACT: A 69-year-old man with locally advanced prostate adenocarcinoma (Gleason score 9), who had completed hormone therapy and definitive radiotherapy, presented to hospital with abdominal pain and distension. A CT scan of the abdomen and pelvis revealed ascites and extensive peritoneal/omental nodules. Serum prostate-specific antigen was not raised (0.07 µg/L). 68 Ga-prostate-specific membrane antigen (PSMA) PET/CT demonstrated PSMA-avid disease in the prostate and widespread PSMA-avid peritoneal/omental and liver metastases but with no PSMA-avid bony metastases. Peritoneal nodule biopsy confirmed metastatic prostate cancer.

FDG PET/CT Imaging of Severe Polymyalgia Rheumatica.

ABSTRACT: A 68-year-old woman was referred for an 18 F-FDG PET/CT for evaluation of arthralgia and raised inflammatory markers, which demonstrated intense FDG activity (SUV max , 25.5) at numerous periarticular and extra-articular sites including the cervical and lumbar interspinous bursae, lumbar facet joints, bilateral ischial tuberosities, and greater trochanters and the aorta consistent with active polymyalgia rheumatica.

Incidental Adiposis Dolorosa (Dercum's Disease) Detected on 18 F-DCFPyL PET/CT.

ABSTRACT: A 64-year-old man with recently diagnosed prostate adenocarcinoma and Gleason score 4 + 3 = 7 with a mildly elevated prostate-specific antigen of 5.17 µg/L was referred for 18 F-DCFPyL PET/CT for primary staging. The scan demonstrated incidental innumerable moderately avid subcutaneous nodules due to adiposis dolorosa (Dercum's disease), which is a rare adipose tissue disease.

Comparison between PSMA PET/CT and MRI for Characterizing Hepatocellular carcinoma: A Real-World Study.

Prostate specific membrane antigen (PSMA) is expressed by hepatocellular carcinoma (HCC). PSMA PET/CT has potential as an imaging agent for the detection of HCC including early diagnosis and monitoring for recurrence following surgical resection. This study aims to compare PSMA PET to standard surveillance imaging in the detection of HCC. Patients with suspected or treated HCC were prospectively recruited from a tertiary hospital outpatient clinic. In addition to routine surveillance imaging as recommended by the multidisciplinary team, a PSMA PET/CT was performed. Imaging and clinical characteristics were compared over a follow-up period of up to 12 months. In a cohort of 19 patients with known HCC or suspected recurrent HCC, PSMA PET/CT had similar efficacy to MRI for the detection of HCC, with a sensitivity of 91% and a specificity of 70% and sensitivity of 87% and a specificity of 73% for PSMA PET/CT and MRI, respectively. PSMA PET/CT had a higher negative predictive value of 90%. In this relatively large single centre study, PSMA is shown to have promising equivalence in performance and its role should be further evaluated in multi-centre prospective trials.

Iron Polymaltose Infusion Effects on Bone Scintigraphy and Remodeling.

ABSTRACT: A 73-year-old woman with metastatic breast cancer and known widespread skeletal metastases was referred for bone scintigraphy. Delayed images acquired at 2 and 5 hours postinjection of 30 mCi (1089 MBq) 99mTc-HDP demonstrated markedly reduced bony uptake, markedly increased renal activity, and significantly increased soft tissue accumulation. By contrast, appropriate skeletal uptake of 99mTc-HDP was seen in prior bone scans. The patient had been treated for iron deficiency anemia with an infusion of 1 g of iron polymaltose approximately 22 hours before injection of 99mTc-HDP. This phenomenon may be due to transient reduced bone resorption with increased FGF23 release secondary to IV iron supplementation.

Peritoneal-scrotal dialysate leakage demonstrated on SPECT/CT imaging in a patient on peritoneal dialysis.

A 62-year-old male with end-stage renal failure on peritoneal dialysis presented with sudden onset scrotal swelling following a violent coughing fit. He was referred for a peritoneal leak study to evaluate the scrotal swelling. This case illustrates the benefit of SPECT/CT imaging in the diagnosis and anatomic localization of peritoneal leakage as a complication of peritoneal dialysis.

Incidental prostate-specific membrane antigen-avid glioblastoma detected on 68Ga-prostate-specific membrane antigen PET/CT.

A 74-year-old man was referred for a 68Ga-prostate-specific membrane antigen (PSMA) PET/CT scan for newly diagnosed prostate cancer which confirmed the presence of PSMA avid cancer in the right gland with no evidence of PSMA metastasis. Incidentally, there was a markedly PSMA avid (SUVmax 7.0) lobulated periventricular mass in the region of the left basal ganglia which was T2 hyperintense and T1 hypointense with perilesional oedema and vivid Gadolinium enhancement on MRI. The patient underwent stereotactic guided biopsy which confirmed LHD wild-type glioblastoma (WHO grade IV).

Accessory Thyroid Tissue Detected Using 131 I SPECT/CT Imaging.

ABSTRACT: Thyroid ectopia has been described as a rare congenital anomaly, characterized by the presence of a thyroid gland in locations other than the orthotopic pretracheal location. The prevalence of accessory thyroid tissue in patients undergoing postablative radioiodine therapy in a 12-month period at a tertiary hospital nuclear medicine department was assessed. Fifty-seven patients were treated between September 2020 and September 2021. Retrospective analysis identified the presence and location of all accessory thyroid tissue separate from the orthotopic pretracheal thyroid gland. Accessory thyroid tissue was present in 21.1% (12/57) of the patients. Accessory thyroid tissue was most commonly located in the lingual region.

A rare case of urachal mucinous adenocarcinoma detected by 18F-FDG PET/CT and MRI.

Urachal adenocarcinomas are rare cancers of the urinary bladder. Both CT and MRI are useful imaging modalities for the diagnosis and evaluation of urachal adenocarcinoma. Unlike CT or MR, there have been variable FDG PET findings with urachal tumours potentially due to considerable variation in their hypermetabolism. We present the case of a 24 year-old female patient who was diagnosed with urachal mucinous adenocarcinoma with characteristic features on CT and MRI which also exhibit moderately increased FDG avidity.

Incidental Intrahepatic Hepatocellular Cholangiocarcinoma Detected on 68Ga-PSMA PET/CT.

ABSTRACT: A 69-year-old man with intermediate-risk prostate cancer and a mildly elevated prostate-specific antigen of 8.2 µg/L was referred for 68Ga-prostate-specific membrane antigen (68Ga-PSMA) PET/CT for primary staging. An incidental intensely 68Ga-PSMA-avid hepatic focus was seen on PSMA PET and subsequent FDG PET/CT and MRI cholangiogram. This was confirmed to be hepatocellular cholangiocarcinoma on subsequent histopathological examination.

Steroid responsive inflammatory myofibroblastic tumor of the lung evaluated by FDG PET/CT imaging.

A 68-year-old gentleman was referred for 18F-FDG PET/CT for a pulmonary mass in the left upper lobe which demonstrated intensely FDG-avid confluent pulmonary consolidation in the left upper lobe (SUVmax 15.1). Histopathologic biopsy of the left upper lobe lung mass was consistent with inflammatory myofibroblastic tumor (IMT). The patient was started on steroid treatment in conjunction with antibiotics. Follow-up FDG PET/CT 3 weeks after commence of treatment showed remarkable response of the IMTs to therapy with much less avid FDG uptake (SUVmax 5.4) and marked improvement in the pulmonary consolidation. Nevertheless, the patient underwent left upper lobe lobectomy due to evidence of persistent cystic disease and malignant potential associated with IMTs. Final histopathology was consistent with IMT with no evidence of malignancy.