Utility of metabolic ratios in the diagnosis of tumor Thrombus on F-18 FDG PET/CT.

BACKGROUND: This study aims to predict quantitative parameter in form of metabolic ratios to diagnose tumor thrombus on F-18 FDG PET/CT. METHODS: This is a retrospective study from Nuclear Medicine department at All India Institute of Medical Sciences, Jodhpur, India. Patients with malignancies who underwent F-18 FDG PET/CT in our department or images sent for review from February 2020 till September 2022 were screened for tumor thrombus that comprised study group. Control group had patients with malignancy and no imaging evidence of tumor thrombus. Metabolic activities (SUVmax) of tumor thrombus, liver and descending aorta in study group, and that of IVC, liver and descending aorta in control group were recorded. Metabolic ratios of tumor thrombus to liver (SUR L) and to aorta (SUR A) in study group, and IVC to liver (SUR* L) and to aorta (SUR*A) in control group were compared using receiver operator curves. RESULTS: Of 2277 studies screened, 12 had tumor thrombus. The most common primary malignant site and vessel involved were lung and IVC respectively. The median (IQR) SUR L, SUR A, SUR* L and SUR* A were 2.5 (3.25), 2.6  (6), 0.67 (0.18) and 1 (0.17) respectively. Area under ROC for SUR L and SUR A were 0.983 [95% CI: 0.955-1.0] and 0.958 [95% CI: 0.90-1.0] respectively. The ideal cut-off for SUR L was 0.953 (sensitivity 92.3%, specificity 98.0%) and for SUR A was 1.42 (sensitivity 84.6%, specificity 98.0%). CONCLUSION: Metabolic ratios of tumor thrombus to liver (SUR L) and aorta (SUR A) have good diagnostic performance and can be useful in studies with non-iodinated contrast CT.

Presentation of metastatic carotid body paraganglioma on F-18 FDG PET/CT: a rare disease.

Carotid body paraganglioma is a slow growing tumor of head and neck region. It can rarely be malignant in nature which is characterized by distant metastases on anatomical imaging. We share an interesting presentation of a malignant carotid body on F-18 FDG PET/CT in form of liver and skeletal metastases.

Atypical Presentation of Gall Bladder Adenocarcinoma as Paraneoplastic Myeloneuropathy.

ABSTRACT: Paraneoplastic neurologic syndromes are a rare, heterogeneous group of complications associated with malignancy, unrelated to direct tumor invasion or metastasis. They are the remote effects of a malignancy owing to immune-mediated reaction toward the antigens that are common to both the malignant and normal cells. Few paraneoplastic syndromes are reported with gall bladder cancer. However, neurological symptoms are infrequent. Here we share an interesting case of adenocarcinoma of gall bladder with initial presentation as a paraneoplastic noncompressing myeloneuropathy.

Primary hepatic diffuse large B- cell lymphoma mimicking cholangiocarcinoma.

Primary lymphoma of liver is a rare malignancy with non-specific clinical features and tumor markers. The presentation and imaging features may be indistinguishable from other hepatic malignant lesions. Pathological diagnosis is the gold standard, and early detection is essential to choose the treatment modality. Here, we share an interesting case of Primary Diffuse Large B cell lymphoma of liver and its imaging findings on Computed tomography (CT), Magnetic Resonance Imaging (MRI) and F-18 FDG PET/CT.

Diagnostic performance of F-18 FDG PET/CT in differentiating autoimmune pancreatitis from pancreatic cancer: a systemic review and meta-analysis.

OBJECTIVES: This study aims to evaluate the utility of F-18 FDG PET/CT in the non-invasive diagnosis of autoimmune pancreatitis (AIP) and differentiating it from pancreatic cancer (CaP) based on the amount and pattern of FDG uptake, as well as involvement of extra-pancreatic sites. METHODS: A systematic search was conducted using PubMed, Scopus, Cochrane Library and Google Scholar. Only those studies that compared the findings of F-18 FDG PET/CT in terms of SUVmax, pattern of FDG uptake and presence of FDG-avid extra-pancreatic sites in both AIP and CaP were included. Studies were qualitatively assessed for risk of bias and publication bias. The diagnostic performance of parameters on PET/CT was examined through pooled sensitivity, specificity, diagnostic odd's ratio (DOR) and summary receiver operator characteristic (SROC) curve analysis. RESULTS: Six studies were included with a total of 580 patients. 178 patients had AIP (Age 18-90 years, male, M: female, F ratio-8.4:1) and 402 patients had CaP (Age 22-88 years, M:F ratio-1.5:1). Type of AIP was reported in only 3 studies, with the included cases predominantly being type 1 AIP. All studies were retrospective with heterogeneity and a risk on patient selection and index test. The FDG uptake, expressed as SUVmax, was lower in AIP with a weighted mean difference of -3.11 (95% confidence interval, CI: -5.28 to -0.94). To diagnose AIP, the pooled sensitivity, specificity and DOR of diffuse pattern of FDG uptake were 0.59 (95% CI: 0.51-0.66), 0.89 (95% CI: 0.86-0.92) and 21.07 (95% CI: 5.07-88.32), respectively, with an area under curve (AUC) of 0.717 on SROC analysis. The pooled sensitivity, specificity and DOR of FDG-avid extra pancreatic sites were 0.55 (95% CI: 0.45-0.65), 0.58 (95% CI: 0.52-0.64) and 2.33 (95% CI: 1.40-3.89), respectively, with an AUC of 0.632. CONCLUSION: On F-18 FDG PET/CT, a pancreatic lesion of AIP has a lower SUVmax value than CaP. A diffuse pattern of FDG uptake and presence of an extra-pancreatic FDG-avid site are nearly 21 times and twice more likely in AIP than CaP, respectively.

Heterotopic Pancreas Mimicking Metastases From Renal Carcinoma: A Rare Differential.

ABSTRACT: Heterotopic pancreas, also known as ectopic or aberrant pancreas, is described as the deposits of normal pancreatic tissue "dropped" into the developing gastrointestinal system. Here we present an operated case of renal clear cell carcinoma, which on 6-month follow-up presented with eccentric mass in the gastric body suspicious for malignancy. Endoscopic biopsy was inconclusive and showed isometabolism on 18F-FDG PET/CT. It was subsequently resected laparoscopically, and final histopathology revealed heterotopic pancreas.

Metastasis from Cervical Cancer Presenting as a Pancreatic Head Mass - an Unexpected Diagnosis!

Cervical cancer is the most common malignancy in Indian women. After primary treatment, distant recurrence is rare and occurs at liver, lung or bone. Distant metastases to other abdominal sites are very rare. We present a case of pancreatic metastasis from cervical cancer, which has not been reported in literature. A 53-year-old woman presented with 3-month history of dull upper abdominal pain with anorexia and weight loss. Past medical history revealed a stage 3c squamous cell carcinoma (SCC) cervix treated by chemo-radiotherapy 2 years back. Contrast CT abdomen showed a pancreatic head mass encasing portal vein. CA-19.9 was 30.8 U/ml. 18-Fluorodeoxyglucose(FDG) PET/CT whole body scan showed avid pancreatic head mass and right lung nodule with no uptake in utero-cervix, adnexae or pelvic nodes. Endoscopic ultrasound-guided needle aspiration from the mass showed metastatic SCC, confirming pancreatic metastasis from SCC cervix with no active disease at the cervix. Being aware of recurrence at such atypical locations during post-treatment follow-up, helps in accurate diagnosis and appropriate treatment.

F-18 FDG PET/CT in staging and response assessment of primary cutaneous diffuse large B-cell lymphoma (leg type).

Primary cutaneous Diffuse Large B-Cell Lymphoma-leg type (PCDLBCL-LT) is a rare subtype of cutaneous lymphomas, with high frequency of extra-cutaneous relapse and poor prognosis. We report a case of 70-year-old lady who was diagnosed with PCDLBCL-LT on biopsy and underwent a baseline F-18 FDG PET/CT, followed by interim and post-treatment PET/CTs. With this case report, we highlight the findings of F-18 FDG PET/CT in the staging of this cutaneous lymphoma, and also emphasize on its role in the response assessment.

18 F-FDG PET/CT of Alveolar Rhabdomyosarcoma of Prostate in a 17-Year-Old Boy.

ABSTRACT: Rhabdomyosarcoma of the prostate is a rare malignancy that usually presents in childhood and adolescence with symptoms of bladder outlet obstruction. Serum prostate-specific antigen is usually normal, and 18 F-FDG PET/CT has a crucial role to rule out distant metastases. We present a case of alveolar rhabdomyosarcoma of the prostate in a 17-year-old boy.

Interesting Presentation of Mycosis Fungoides in Staging on F-18 FDG PET/CT.

Mycosis fungoides is the major form of primary cutaneous T cell lymphoma. Its staging is based on the percentage of body surface involvement and biopsy-proven extra cutaneous nodal or visceral involvement. Literature shows F-18 FDG accumulation in disease-involved nodes and viscera with non-specific uptake due to co-existing inflammation limits its specificity. We report an interesting case of mycosis fungoides with bilateral upper limb edema and share its findings on F-18 FDG PET/CT.

Necrotizing granulomatous inflammation mimicking skeletal metastasis: a possible differential diagnosis.

Tuberculosis is an endemic disease in India for decades, and its coexistence in the patients with malignancy cannot be ignored. The non-specific uptake of 2-deoxy-2-[fluorine-18] fluoro-D-glucose in active infection and malignancy can affect the diagnosis and management of patients. However, characteristic anatomical features of the lesion aid not only in its localization but also in diagnosis. We share an interesting case of necrotizing granulomatous inflammation of dorsal spine mimicking skeletal metastases in a treated case of carcinoma cervix.

Sub-Diaphragmatic Haemangioma Suspected on F-18 Fdg Pet/Ct Confirmed by Rbc Scintigraphy.

A 53-year-old woman presented with left submandibular gland carcinoma. Contrast-enhanced computerized tomography done for staging revealed suspicious metastatic omental deposit adjacent to left hemi-diaphragm apart from primary and cervical nodal metastasis. Staging F-18 fluorodeoxyglucose (FDG) positron emission tomography-computed tomography showed high FDG uptake in the primary and metastatic left cervical lymph nodes. However, no FDG uptake was seen in left sub-diaphragmatic mass. Known vascular malformations sites in the left posterior triangle of the neck and liver hemangiomas also showed no uptake. This pattern of uptake raised a suspicion of multiple vascular malformations. Tc-99 m red blood cell scintigraphy was done which confirmed the nature of subdiaphragmatic lesion as haemangioma.

Lutetium therapy-induced carcinoid crisis: A case report and review of literature.

Peptide receptor radionuclide therapy with 177lutetium (Lu)-labeled somatostatin analogs is a promising new tool in the management of patients with inoperable or metastatic neuroendocrine tumors. Some of these patients may present with carcinoid syndrome and it is known that rarely carcinoid crisis can be precipitated by surgical or other interventions in these patients. However, there are anecdotal reports of carcinoid crisis after Lu-labeled peptide therapy. We are reporting our experience of successful management of one such case of carcinoid crisis which was precipitated by Lu therapy.

Thoraco-Abdominal Duplication Cyst- Role Tc-99m Pertechnetate SPECT-CT Scintigraphy in Localising Ectopic Gastric Mucosa.

Thoraco-abdominal duplication cyst, a congenital malformation of the posterior primitive foregut rarely presents with anaemia. Ectopic gastric mucosa is seen in around 20%-30% of the enteric duplication cysts. We report the scintigraphic findings of one such case which helped in final diagnosis and management of the patient.

Contamination, a Major Problem in Nuclear Medicine Imaging: How to Investigate, Handle, and Avoid It.

We present a case study in which artifacts from collimator contamination and patient motion were seen on a bone scan. Any identified artifact must be further investigated and documented so as to detect its source and thus prevent its future occurrence.