Role of 68 Ga-FAPI PET/CT in Assessing Hepatobiliary Malignancies : A Prospective Pilot Study.

INTRODUCTION AND AIM: Preliminary studies showed good expression of fibroblast activating protein inhibitor (FAPI) in hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC). Our aims were to study the diagnostic performance of 68 Ga-FAPI PET/CT in diagnosing the primary hepatobiliary malignancies and to compare its performance with 18 F-FDG PET/CT. PATIENTS AND METHODS: Patients suspected to have HCC and CC were recruited prospectively. FDG and FAPI PET/CT studies were completed within 1 week. Final diagnosis of malignancy was achieved by tissue diagnosis (either histopathological examination or fine-needle aspiration cytology) and radiological correlation from conventional modalities. Results were compared with final diagnosis and expressed as sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy. RESULTS: Forty-one patients were included. Thirty-one were positive for malignancy and 10 were negative. Fifteen were metastatic. Of 31, 18 were CC and 6 were HCC. For overall diagnosis of the primary disease, FAPI PET/CT performed exceptionally compared with FDG PET/CT with sensitivity, specificity, and accuracy of 96.77%, 90%, and 95.12%, respectively, versus 51.61%, 100%, and 63.41% for FDG PET/CT. FAPI PET/CT clearly outperformed FDG PET/CT for the evaluation of CC with sensitivity, specificity, and accuracy of 94.4%, 100%, and 95.24%, respectively, whereas for FDG PET/CT sensitivity, specificity, and accuracy were 50%, 100%, and 57.14%, respectively. Diagnostic accuracy of FAPI PET/CT was 61.54% for metastatic HCC compared with 84.62% for FDG PET/CT. CONCLUSIONS: Our study highlights the potential role of FAPI-PET/CT in evaluating CC. It also ascertains its usefulness in the cases of mucinous adenocarcinoma. Although it showed a higher lesion detection rate than FDG in primary HCC, its diagnostic performance in the metastatic setting is questionable.

Incidental Detection of Asymptomatic Brain Metastases Due to Carcinoma Prostate in Ga-68 PSMA HBED-CC Positron Emission Tomography-Computed Tomography: Reiterating its Superiority in Assessing Disease Status.

Brain metastasis originating in adenocarcinoma of the prostate is rare and can be expected in cases of disseminated bone and soft-tissue disease. Asymptomatic brain metastasis is rare at any point of the disease stage. Ga-68 PSMA positron emission tomography-computed tomography (PET-CT) is one of the useful investigations for assessing the disease status in adenocarcinoma of the prostate. We report a case of asymptomatic brain metastases detected in Ga-68 PSMA PET-CT scan.

I131 Accumulation in Hydrocele in the Setting of Metastatic Papillary Carcinoma Thyroid.

131I is widely used for the treatment of goiter and residual and metastatic thyroid cancer. Uptake of 131I is mainly due to the expression of sodium-iodide symporter in the target tissues. Incidental third space accumulation in the pleural and pericardial cavity can be encountered due to passive diffusion of tracer into these cavities. We present an interesting finding of 131I accumulation in the scrotal hydrocele in a 70-year-old patient with a metastatic classical variant of papillary thyroid carcinoma, who was treated with 200 m Ci of 131I.

Tc-99m Sulfur Colloid Scintigraphy in Differentiating Fat Sparing from Lymphomatous Involvement of Liver-Old Wine in New Bottle.

Hepatic mass lesions and focal fat sparing in a fatty liver may be difficult to differentiate on contrast-enhanced computed tomography (CT) imaging and F-18-fluorodeoxyglucose positron emission tomography/CT. Tc-99m Sulfur colloid (SC) scintigraphy has been used in the assessment of solid hepatic masses. Liver metastases will appear as focal photopenic defects due to the loss of Kupffer cell function. However, focal fatty infiltration or fat sparing of the liver does not affect Kupffer cell function and thereby leading to normal tracer uptake. Despite several advances in imaging modalities, Tc-99m SC scintigraphy is still a reliable armamentarium in the characterization of hepatic mass lesions.

Tuberculosis in Posttransplant Recipients: Challenges in Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Reporting in Countries with a High Prevalence of Tuberculosis.

Tuberculosis (TB) is a common bacterial infection in developing countries. Solid-organ and hematopoietic stem cell transplant recipients are more prone to this infection. Reactivation from previously acquired infection is the most common mode. It has to be ruled out in cases of pyrexia of unknown origin (PUO) before ruling out the other possibilities. We present two cases of incidentally detected TB in the posttransplant patients referred for the evaluation of PUO.

Serial Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography Scan Distinguishing Infected Seroma from Recurrence in a Necrotic Lymph Node in a Case of Squamous Cell Carcinoma of the Right Kidney.

Seroma can occur as a complication following nephroureterectomy. We report a case of squamous cell carcinoma of the kidney, postnephroureterectomy where serial fluorodeoxyglucose positron emission tomography-computed tomography images helped in distinguishing the diagnostic dilemma between lymph node recurrence and infected seroma.

A Unique Finding of Hepatogastric Fistula in Cervical Cancer Liver Metastasis.

In India, cervical cancer is the second leading cause of cancer-related mortality among females. Around one-third are expected to develop recurrence or metastasis during follow-up. Liver metastasis is rarely requiring palliative treatment. Patient compliance to strict follow-up is vital to detect early metastasis to be able to improve survival. A 58-year-old lady (International Federation of Gynecology and Obstetrics [FIGO] stage IIIB) was treated with concurrent chemoradiotherapy. During follow-up, she had complained of abdominal pain for which cross-sectional imaging revealed a left lobe liver lesion fistulizing into the stomach. Liver metastasis fistulizing into the stomach is a rarity, and a biopsy is required to confirm metastasis or maybe a second primary. Although palliation in the form of chemotherapy is the standard, minor or major hepatectomy can be considered in patients with good performance status at high-volume centers. A tailored multidisciplinary team approach is required for better survival.

Retrosternal Ectopic Thyroid Mimicking Esophagus in Tc-99m Pertechnetate Thyroid Scan.

Abnormal Pertechnetate distribution can occur due to many reasons such as retrosternal extension of eutopic thyroid gland, ectopic functioning thyroid gland, physiological uptake in esophagus, teratoma having functioning thyroid tissue component, metastatic lymph nodes and sequestered thyroid nodule. We present a case of thyrotoxicosis with hyper functioning thyroid gland and two abnormal foci of uptake in the mediastinum in a linear fashion that mimcked esophageal activity. These foci persisted even after consuming water. SPECT localised these foci in retrosternal and likely to be ectopic functioning thyroid. Retrosternal ectopic thyroid tissue may not usually be detected on Tc-99m scan due to attenuation of low-energy gamma rays by sternal bone. However, hyperfunctioning tissue enabled visualization of the retrosternal ectopic thyroid.

Multiple Cutaneous Metastases on 99mTC-HYNIC-TOC Scan in a Rare Case of Malignant Laryngeal Paraganglioma.

Laryngeal paraganglioma is a rare neuroendocrine tumor arising from neural crest cells of larynx, contributing to 0.6% of the laryngeal tumors. Patients usually present with compressive symptoms such as hoarseness of voice. These tumors express somatostatin receptors, which can be imaged with radioligands such as 99mTc labeled hydrazinonicotinyl-Tyr3-octreotide (HYNIC-TOC). The percentage of malignant transformation in laryngeal paraganglioma is 2%, and they usually metastasize to lymph nodes, bone, and liver. Here, we report a 99mTc HYNIC-TOC scan of a 55-year-old male patient with recurrent laryngeal paraganglioma, who presented with painful multiple metastatic cutaneous nodules.