Hot Embolus Artifact Mimicking Disease Progression in Post-therapy 177Lu-DOTATATE Scan: Incremental Value of SPECT/CT.

Peptide receptor radionuclide therapy (PRRT) has become an established treatment for patients with inoperable and/or metastatic, well-differentiated neuroendocrine tumors with overexpression of somatostatin receptor type 2 (SSTR-2). The post-therapy 177Lu-DOTATATE whole-body scan not only assesses the biodistribution of the lesions seen on pre-therapy 68 Ga-SSTR PET/CT scan but also provides a quick assessment of disease status and dosimetry during treatment. Like any other radionuclide scan, the whole-body 177Lu-DOTATATE scan may also show abnormal radiotracer uptake, which may require further imaging to establish its exact etiology. Though radiotracer emboli mimicking focal pulmonary lesions have been described with 18F-FDG and 68 Ga-DOTANOC PET/CT scans, similar artifacts with post-therapy 177Lu-DOTATATE scans have not been described. Herein, we report two cases of hot emboli in the post-therapy 177Lu-DOTATATE scans.

Incidentally Detected Subclinical Limbic Encephalitis on 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in a Patient with Myasthenia Gravis and Sarcoidosis: A Rare Immunological Triad?

Limbic encephalitis is the inflammation of the medial temporal lobe structures due to direct infectious or indirect autoimmune etiology. Sarcoidosis is a rare cause of limbic encephalitis, has been reported by some authors. Association has also been reported between sarcoidosis, myasthenia gravis, and limbic encephalitis. We report an interesting case of 18F-fluorodeoxyglucose positron emission tomography/computed tomography demonstrating limbic encephalitis and sarcoidosis in a known case of myasthenia gravis.

[68 Ga]Ga-PSMA-11 Small Bowel Uptake in Crohn's Disease: Revisiting the "Non-specificity" of PSMA Ligands.

The rapidly evolving clinical utility of prostate-specific membrane antigen (PSMA) PET/CT as an imaging modality for prostate cancer (PCa) has brought to the forefront a multitude of non-prostatic diseases also exhibiting PSMA radioligand uptake. We report a case of a 71-year-old male with PCa who underwent PSMA PET/CT for recurrence evaluation. The scan demonstrated [68 Ga]Ga-PSMA-11 uptake in the distal ileum. Retrospective enquiry revealed that the patient was a known case of Crohn's disease. This case highlights an uncommon finding of PSMA radioligand uptake in the distal small bowel (non-prostatic benign pathological uptake) in a patient with known Crohn's disease, which may be misinterpreted in the evaluation of PCa.

Role of Testicular Scintigraphy in the Assessment of Viability of Undescended Testis: Potential Pitfalls and Complementary Role of 18F FDG PET/CT.

ABSTRACT: Doppler ultrasonography and testicular scintigraphy are sensitive techniques to detect the adequacy of blood flow to testicular tissue. Because Doppler ultrasonography is an operator-dependent imaging modality, it can result in equivocal findings. Testicular scintigraphy proves to be more accurate in such cases, but it may be inconclusive on occasion. The authors report the case of a young man with a left undescended testis where testicular scintigraphy was inconclusive for viability and 18F-FDG PET/CT provided important diagnostic information.

Subclinical Hypothyroidism After 225Ac-DOTATATE Therapy in a Case of Metastatic Neuroendocrine Tumor: Unknown Adverse Effect of PRRT.

ABSTRACT: Radiation-induced thyroid dysfunction is very rarely associated with peptide receptor radionuclide therapy (PRRT) for neuroendocrine tumors using ß-emitting radionuclides. With the emergence of α radionuclide such as 225Ac, PRRT using these radionuclides has shown better results; however, data on the toxicity profile are limited. This is a case report describing the thyroid dysfunction developed in a patient with inoperable metastatic neuroendocrine tumor with unknown primary after PRRT using 225Ac-DOTATATE, which has never been reported previously.

Alpha Before Beta: Exceptional Response to First-Line 225Ac-DOTATATE in a Patient of Metastatic Neuroendocrine Tumor With Extensive Skeletal Involvement.

ABSTRACT: The utility of ß-emitter 177Lu-DOTATATE in patients of neuroendocrine tumors (NETs) with widespread skeletal metastases is limited by its relatively modest response rates and a significant concern for hematotoxicity. In such situations, targeted α therapy with 225Ac-DOTATATE can be potentially beneficial. In this report, a 46-year-old man with rectal NET and extensive skeletal metastases was treated upfront with 6 cycles of 225Ac-DOTATATE at 8 weeks' intervals. The patient showed excellent symptomatic, biochemical, and radiological response with no grade 3/4 adverse events. The first-line use of 225Ac-DOTATATE, therefore, presents a novel strategy for metastatic NETs with high skeletal disease burden.

A Rare Case of Massive Bilateral Renomegaly due to Primary Involvement by Mantle Cell Lymphoma on 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography.

Mantle cell lymphoma (MCL) is a rare subtype of B-cell non-Hodgkin's lymphoma with an annual incidence of 5%, common in men with a median age of 60-70 years. Renal involvement is seen in about 0.7% of the extranodal lymphomas. The bilateral presentation is seen in 10%-20% of cases. There have been many case reports of MCL with renal involvement; however, primary renal involvement by MCL is extremely rare. We hereby describe the 18F-fluorodeoxyglucose positron emission tomography/computed tomographic findings in primary MCL involving the bilateral kidneys.

Versatile Role of 18F-FDG PET/CT in a Patient with Pan-cerebellar Paraneoplastic Manifestation Due to Underlying Hodgkin's Lymphoma.

Hodgkin's lymphoma most commonly presents as painless lymphadenopathy and systemic B symptoms like fever, night sweats, and weight loss. But rarely, it can present with unusual paraneoplastic manifestations. In the present case, we report a 30-year-old woman who presented with sub-acute onset pan-cerebellar symptoms. The serum neuronal antibody panel was negative. She underwent F-18 FDG PET/CT to evaluate the neoplastic etiology as the underlying cause, which demonstrated both the primary etiology and the paraneoplastic changes in the brain.

Effect of COVID-19 on 18F-FDG PET/CT: Is There a Need to Consider COVID-19 Status Before Planning 18F-FDG PET/CT for Oncologic Evaluation?

Incidental detection of coronavirus disease 2019 (COVID-19)-related lung changes on 18F-FDG PET/CT images of oncology patients has been increasingly reported. Most of the case reports or series have stressed the retrospective diagnosis of COVID-19 with the help of 18F-FDG PET/CT lung findings. In this case report, we introduce a different aspect of COVID-19-related lung changes on 18F-FDG PET/CT, interfering with the evaluation of metastatic lung lesions in a patient with renal cell carcinoma.

Prospective Comparison of Angiogenesis-Specific 68Ga-RGD2 PET/CT Imaging Parameters and DAS28-ESR in Rheumatoid Arthritis.

OBJECTIVE: The aim of this study was to compare the performance of angiogenesis-specific 68Ga-RGD2 PET/CT with Disease Activity Score 28-erythrocyte sedimentation rate (DAS28-ESR) in assessing disease activity and treatment response in rheumatoid arthritis (RA). METHODS: This was a prospective study comparing the performance of 68Ga-RGD2 PET/CT and DAS28-ESR in 30 RA patients. All of them underwent 68Ga-RGD2 PET/CT scan from head to toe and clinical examination at the baseline. A repeat scan and clinical examination were done in 27 patients after 3 months of treatment with disease-modifying antirheumatic drugs ± steroids. Three PET parameters, that is, PJC (PET-positive joint count), aSUVmax (average SUVmax), and hSUVmax (highest SUVmax), of positive joints were compared with the DAS28-ESR for disease activity assessment and response evaluation. RESULTS: Among the 3 PET parameters, PJC showed a significant correlation with the DAS28-ESR (0.64, P < 0.01). A significant change was observed with treatment in the DAS28-ESR and PET parameters of 27 patients at follow-up. There was significant correlation between percentage changes in DAS28-ESR and scan parameters such as PJC (0.689, P < 0.001), aSUVmax (0.712, P < 0.001), and hSUVmax (0.555, P = 0.003) values. The absolute change in aSUVmax value could accurately discriminate (area under the curve, 0.98; P = 0.001) European League Against Rheumatism responders from nonresponders. CONCLUSIONS: 68Ga-RGD2 PET/CT is a promising tool for objective assessment of disease activity and treatment response in patients with RA.

Posttraumatic Scab on 131I Whole-Body Scan-A False-Positive Finding.

ABSTRACT: 131I scan plays a crucial role in the management of patients with differentiated thyroid cancer for the evaluation of remnant thyroid tissue, residual/recurrent metastatic disease, posttherapy tracer distribution, and response assessment to high-dose 131I therapy. Different causes secondary to physiological, pathological, and anatomical variations have been described for false-positive findings in the whole-body planar images. This case report of a patient of differentiated thyroid cancer with undocumented trauma to the left knee region a day before receiving the high-dose radioiodine therapy showed an interesting image finding of tracer uptake at unusual site in the posttherapy whole-body 131I scan.

Prominent aortic radiotracer activity on equilibrium radionuclide ventriculography (ERNV) due to anterior transposition of aorta: A clue to diagnosing levo-transposition of great arteries (L-TGA) ?

Levo-transposition of great arteries (L-TGA) is a rare acyanotic congenital heart anomaly characterized by transposition of morphological left and right ventricles along with their corresponding atrio-ventricular valves in addition to transposition of primary arteries. Many cases of L-TGA are asymptomatic and are diagnosed accidently in adulthood during workup of other conditions. We hereby report a patient with incidentally diagnosed L-TGA who was subjected to Equilibrium Radionuclide Ventriculography (ERNV) for assessment of ventricular function. Planar ERNV images in best septal view showed prominent tracer activity in the anteriorly transposed aorta which can be a helpful clue to raise the suspicion of L-TGA in an asymptomatic adult undergoing ERNV.

Radioactive Iodine as a Single-Modality Treatment in a Tumor Thrombus Arising from Follicular Thyroid Carcinoma.

On rare occasions, differentiated thyroid carcinoma causes tumor thrombosis in the great veins. Multimodality treatment with surgery, radioiodine therapy, and targeted therapies is used to manage tumor thrombosis associated with thyroid malignancies, though no established guidelines exist. We present a woman with a tracer-avid tumor thrombus in the right brachiocephalic vein after surgery for follicular thyroid carcinoma. Follow-up revealed an excellent response after treatment with 131I as a single modality for both remnant and tumor thrombus.

Bilateral Peritoneoscrotal Communication-"Chicken Leg" Appearance Demonstrated on 99mTc-Sulfur Colloid Scintigraphy.

Continuous ambulatory peritoneal dialysis is a convenient alternate form of treatment in patients receiving hemodialysis for renal failure. Sometimes during the procedure, patients may develop scrotal swelling because of patent processus vaginalis. The diagnostic utility of the peritoneal scintigraphy, an infrequently performed nuclear medicine scan to identify peritoneoscrotal communication, has been reported by many authors. Most of the previous case reports in the literature demonstrated unilateral peritoneoscrotal communication. We present an interesting Tc-sulfur colloid peritoneal scintigraphic image finding of bilateral peritoneoscrotal communication in a 67-year-old man who developed scrotal swelling while undergoing continuous ambulatory peritoneal dialysis.

Triple Tracer Positivity in Metastatic Lymph Nodes from Well-Differentiated Neuroendocrine Tumor in MEN-1 Syndrome.

Patients with multiple endocrine neoplasia type 1 usually have a combination of endocrine disorders due to lesions in the pancreas, parathyroid gland, and pituitary gland. Functional imaging using different tracers in addition to conventional imaging are applied in localizing the primary sites, determining the disease extent, and characterizing the lesions. We present a diagnosed case of multiple endocrine neoplasia type 1 with interesting incidental imaging findings showing 99mTc-sestamibi and 18F-fluorocholine uptake in addition to 68Ga-DOTANOC uptake in metastatic mediastinal and cervical lymph nodes arising from gastroenteropancreatic neuroendocrine tumor. This case shows the possibility of imaging the neuroendocrine tumors with 3 different tracers, namely 68Ga-DOTANOC, 99mTc-sestamibi, and 18F-fluorocholine.

A Comparison of Angiogenesis and Glycolytic Imaging in Patients With Clinical Suspected Locally Advanced Breast Cancer.

F-FDG PET/CT imaging is an important diagnostic tool for accurate staging and assessment of response to neoadjuvant chemotherapy (NACT) in patients with locally advanced breast carcinoma (LABC). However, F-FDG being non-specific marker, it also accumulates in inflammatory conditions, leading to false positive results. Angiogenesis, an essential characteristic for tumor development, intrusion and metastasis can be imaged using Ga-labeled RGD tripeptide. We here depict a series of clinically staged LABC patients who underwent both Ga-DOTA-RGD2 and F-FDG PET/CT imaging for staging and illustrate the similarities and significant differences between the two tracers.

18F-FDG PET/CT Demonstrates Renal Cell Cancer in a Transplant With Synchronous Intestinal Infection.

We present a case of a 22-year-old man with history of allogenic renal transplantation on immunosuppression, who underwent F-FDG-PET/CT to characterize a lesion in the transplanted kidney on ultrasonogram and contrast-enhanced computed tomography imaging. PET/CT revealed FDG avid lesion in the transplanted kidney and mural thickening involving the distal ileum, ileocecal junction, and ileocolic lymph nodes. Subsequent histopathological examination from the renal lesion revealed renal cell carcinoma in the transplanted kidney. Additionally, endoscopic biopsy from the ileal thickening revealed granulomatous inflammation, suggesting tuberculosis, which was missed on both ultrasonogram and contrast-enhanced CT imaging.