Incidentally Detected Gallbladder Carcinoma: Can F-18 FDG PET/CT Aid in Staging and Prognostication?

Purpose: Incidental gallbladder carcinoma (IGBC) is diagnosed in post-cholecystectomy specimens for benign indications, where the role of 2-fluro-2-deoxyglucose positron emission tomography/computed tomography(FDG-PET/CT) is not clearly defined. The present study aimed to assess the benefits of staging and prognosticating with FDG-PET/CT in IGBC. Materials and Methods: A retrospective observational study from a tertiary-care center from January 2010 to July 2020 was performed. The demographic, clinical, histopathological, and treatment-related histories were collected. FDG-PET/CT-image findings were compared with survival outcomes through telephonic follow-up. The chi-square test was used for comparing frequencies. The univariate and multivariate survival estimates were analyzed using the Kaplan-Meier analysis and the Cox-proportional hazard model, respectively. Log-rank test was used to compare the Kaplan-Meier curves. Results: The study included 280 postcholecystectomy participants (mean age: 52 ± 11 years; women: 227) of whom 52.1% had open surgery(146/280). Residual disease in the gallbladder fossa (54.8% vs. 36.6%, p = 0.002) and liver infiltration (32.9% vs. 22.4%, p = 0.05) were seen more frequently in open surgery compared to laparoscopic surgery, while anterior abdominal wall deposits were more common in laparoscopy(35.1% vs. 24%,p = 0.041). FDG-PET/CT changed the management in 10% (n = 28) of patients compared to contrast-enhanced CT. The median survival was 14 months (95%CI-10.3-17.7). A higher stage of the disease on the FDG-PET/CT (loco-regional disease-HR 4.86, p = 0.006; metastatic disease-HR 7.53, p < 0.001) and the presence of liver infiltration (HR-1.92, p = 0.003) were independent predictors of poor survival outcomes. Conclusion: FDG-PET/CT detects residual and metastatic disease in patients with IGBC, enabling the institution of appropriate management and acting as a tool for prognostication of survival.

Potential Role of 68Ga-NOTA-Duramycin PET/CT Imaging for Early Response Evaluation in a Lymphoma Patient: A Case Report.

ABSTRACT: Duramycin, a 19 amino acids peptide, is known for its potential to target phosphatidylethanolamine. During cell death (apoptosis), rearrangement of membrane phospholipids results in the externalization of phosphatidylethanolamine to the outer leaflet of the cell membrane, which can be imaged using 68Ga-NOTA-duramycin. We report 68Ga-NOTA-duramycin imaging in a 50-year-old man with biopsy-proven diffuse large B-cell lymphoma planned for anthracycline-based chemotherapy. 68Ga-NOTA-duramycin PET/CT imaging along with 18F-FDG PET/CT was performed before and after 2 cycles of chemotherapy. The tracer avidity in interim 68Ga-NOTA-duramycin PET/CT showed its diagnostic potential to assess early response to chemotherapy.

Cystic hepatic metastases in treatment naïve neuroendocrine tumor: Cytomorphology clubbed with cell block immunocytochemistry clinches the diagnosis.

Cystic hepatic lesions encompass a vast spectrum of infectious, non-neoplastic, and neoplastic entities. Most hepatic cysts are benign and asymptomatic, requiring no active intervention. However, symptomatic and malignant cysts need proper evaluation and specific treatment. An accurate preoperative diagnosis is pivotal for patient management. At times, these lesions may mimic, especially symptomatology and radiology, leading to a diagnostic ordeal. We herein present a case of a patient with cystic liver lesions in a treatment naïve neuroendocrine tumor that was a diagnostic dilemma on radiology. Low cellularity of cytology smears made the diagnosis challenging, and cell block immunocytochemistry finally clinched the diagnosis. A timely diagnosis provided on cytology fuelled further work-up, the discovery of primary tumor, and initiation of appropriate therapy.

Ex vivo Measurement of the Radioactivity of PET/CT-Guided Biopsy Specimen: Is it Helpful to Confirm the Sampling from a Viable Region of the Tumor and the Nature of the Lesion?

Objective: Ex vivo radioactivity measurement of positron emission tomography/computed tomography (PET/CT)-guided biopsy tissue specimen to check the viable tumor sampling and predict the nature of the biopsied lesion. Materials and Methods: We prospectively evaluated the retrieved tissue specimens during PET/CT-guided biopsies for the presence of radioactivity. The qualitative radioactivity was measured by acquiring PET/CT images of the specimen. For quantitative analysis, a multichannel-analyzer (MCA) was used, and a counting-factor (CF) in counts/mCi.mm3 was calculated based on background-corrected net-counts, tissue-volume (mm3), and exponential tracer-activity during biopsy (mCi). The CF-values were compared with the 2-(fluorine-18) fluoro-2-deoxy-D-glucose-avidity in the target lesion and correlated with the histopathology. Results: A total of 49 patients (30 males) aged 51.8 ± 17.8 years were recruited for the biopsy, and radioactivity was measured. All the specimens revealed the presence of radioactivity on PET/CT images of the specimens and MCA counting. The mean CF-values were 17.2 ± 15.6 counts/mCi.mm3. One sample had meager counts with a CF-value of 0.162 and was subjected to re-biopsy after repositioning the coaxial needle to the hypermetabolic site. Pathological diagnosis was established in all the patients (malignancy-29, benign-20). The CF-values were significantly higher in malignant lesions than benign (21.45 ± 18.05 vs. 10.76 ± 8.96 counts/mCi.mm3, P = 0.025). CF-values and maximum standardized uptake value had a significant correlation (Pearson's r = 0.457, P = 0.001). Conclusion: The ex vivo measurement of the radioactivity of retrieved tissue specimens during PET/CT-guided biopsy helps to confirm the sampling from viable region and a highly practical approach to avoid erroneous sampling of a lesion with a large necrotic area. It is also helpful in predicting the nature of the biopsied lesion before the histopathological analysis.

Bilaterally ectopic pelvic kidneys masquerading as horseshoe kidney in Fanconi anemia.

Fanconi anemia (FA) is a genetic disease associated with the risk of different congenital malformations, bone marrow failure, and predisposition to cancer. Congenital abnormalities of the kidney and urinary tract are not infrequent in FA with renal ectopia being one of them. The incidence of the bilateral pelvic ectopic kidney is restricted to only a few reported cases; however, its association with FA has never been reported in the literature. We present a case of Fanconi anemia in a young girl with apparently fused kidneys on a 99mTc-DMSA planar scan which was confirmed to be bilateral pelvic kidneys on hybrid cross-sectional imaging.

Incidental Detection of Viral Conjunctivitis on 68Ga-DOTANOC PET/CT in a Patient Suspected With Von Hippel-Lindau Syndrome.

ABSTRACT: Von Hippel-Lindau syndrome is an autosomal dominant disorder. It is associated with a spectrum of benign and malignant tumors, including pancreatic and adrenal neuroendocrine tumors, renal cell carcinoma, and hemangioblastomas of the central nervous system and retina. 68Ga-DOTANOC PET/CT has shown somatostatin receptor expression in inflammatory conditions. In the present case, we report that 68Ga-DOTANOC PET/CT demonstrates the tracer avidity in the bilateral swollen eyelids in a patient with clinical suspicion of Von Hippel-Lindau syndrome, which was confirmed as viral conjunctivitis on clinical examination.

Safety and Diagnostic Yield of 68Ga Prostate-specific Membrane Antigen PET/CT-guided Robotic-assisted Transgluteal Prostatic Biopsy.

Background Transrectal US-guided biopsy with or without MRI fusion is performed for diagnosing prostate cancer (PCa) but has limitations. Gallium 68 (68Ga) prostate-specific membrane antigen (PSMA) PET/CT-guided targeted biopsy has the potential to improve diagnostic yield of PCa. Purpose To evaluate the safety and diagnostic yield of 68Ga PSMA PET/CT-guided, robotic-arm assisted transgluteal prostatic biopsy. Materials and Methods In this single-center nonrandomized prospective trial, participants with a clinical suspicion of PCa (serum prostate-specific antigen level > 4 ng/mL) were recruited from January 2019 to September 2020. After whole-body 68Ga PSMA PET/CT, participants with PSMA-avid intraprostatic lesions underwent PET-guided transgluteal biopsy by using an automated robotic arm. To assess safety and diagnostic yield, procedure-related complications and histopathologic results were documented. Pain during the procedure was scored by a visual analog scale. Descriptive statistics were applied; qualitative variables were reported in percentages. Results Seventy-eight participants (mean age, 66 years ± 7 [standard deviation]; 36 participants [46%] with prior negative results at transrectal US-guided biopsy) were enrolled. Fifty-six (72%) participants had PSMA-avid lesions (prior negative results at transrectal US-guided biopsy in 22 of 56 [39%]) and underwent targeted biopsy. PCa was confirmed in 54 of 56 (96%) participants, and clinically significant PCa (Gleason score ≥ 7) was confirmed in 24 of 54 (44%). Two participants had nonrepresentative samples that required rebiopsy. All participants experienced pain during the procedure, mild (median visual analog scale score, 1; interquartile range, 1-2) in 36 of 56 (64%) and moderate (median visual analog scale score, 5; interquartile range, 5-6) in 20 of 56 (36%). Postprocedure complications were noted in five of 56 (9%) participants and were minor (hematuria, four participants; hematospermia, one participant; and gluteal pain, two participants). No participant developed a postprocedural infection. Conclusion Transgluteal prostate-specific membrane antigen (PSMA) PET/CT-guided, robotic-targeted prostatic biopsy is safe with a high diagnostic yield of prostate cancer for PSMA-avid lesions. Clinical trial registration no. NCT05022576 © RSNA, 2022.

Toxic thyroid adenoma with hypercalcemia mimicking an intra-thyroidal parathyroid adenoma.

Hypercalcemia is a clinical condition characterized by elevated circulating serum calcium levels either due to raised parathyroid hormone in hyperparathyroidism or due to secondary causes of hypercalcemia without elevated parathyroid hormone levels. However, hyperthyroidism may occasionally present with incidentally detected hypercalcemia. We present a case of a 53-year-old woman with a previous history of an underlying thyroid disorder, now presented with features of hypercalcemia and mildly elevated parathyroid hormone levels. Her ultrasonography of the neck was suggestive of an intra-thyroidal parathyroid adenoma and it was localized as a tracer avid lesion within the thyroid gland on dual-phase 99mTc-sestamibi planar scintigraphy with single photon emission computed tomography/ computed tomography (SPECT/CT). However, a subsequent thyroid profile followed by 99mTc- pertechnetate thyroid scintigraphy showed a hot nodule in the thyroid gland which changed the diagnosis to a toxic thyroid adenoma. She was treated with radioactive iodine ablation and thyrotoxicosis resolved and the serum calcium levels normalized on her follow-up.

Fluoro-2-Deoxyglucose-Positron Emission Tomography/Computed Tomography in the Diagnosis and Management of Adrenocortical Carcinoma: A 10-Year Experience from a Tertiary Care Institute.

Purpose: Adrenocortical carcinoma (ACC) is a rare primary malignancy of the adrenal gland. The present study was aimed to compare the performance of fluoro-2-deoxyglucose-positron emission tomography-computed tomography (FDG-PET-CT) compared to contrast-enhanced computed tomography (CECT) in diagnosis and management of ACC. Materials and Methods: A retrospective analysis of the PET-CT studies from January 2010 to October 2020 was performed. Patients with adrenal lesions suspicious of ACC and diagnosed cases of ACC who underwent PET-CT for staging, restaging, and surveillance were reanalyzed. The PET-CT parameters were compared with the clinical, biochemical, histopathological, and CECT parameters. Results: The study included 96 scans performed in 77 patients (36 males, aged 40.4 ± 17.9 years). Of these, 55 scans were performed to diagnose and stage suspected ACC (30 of them diagnosed as ACC), 31 for restaging, and 10 scans for surveillance of ACC. PET/CT revealed metastases from an extra-adrenal primary in 5/55 patients. FDG-PET-CT had a sensitivity and specificity of 100% and 70% to diagnose ACC. Standardized uptake value-peak more than 5.4 had a sensitivity of 90.9% and specificity of 91.7% for differentiating ACC from non-ACC lesions, while tumor-to-liver ratio peak (TLRpeak) of 3.3 was most specific. PET-CT changed the staging in 23.3% of the patients with an accuracy of 100%. PET-CT changed the management plan in 25.8% of the patients during restaging with a sensitivity and specificity of 95.6% and 100%, respectively. For surveillance, CECT was as sensitive as PET-CT; however, PET-CT was more specific (100% vs. 97.9%). Conclusion: FDG-PET-CT performs better than CECT in the diagnosis, staging, restaging, and surveillance of ACC.

Ga-68 Chemokine Receptor-4 PET/CT Imaging in Schminke Type of Nasopharyngeal Carcinoma.

Nasopharyngeal carcinoma is a rare malignancy of the head-and-neck region. It is associated with Epstein-Barr virus infection and smoking. Its association with breast cancer is also infrequent. Chemokine receptor (CXCR)-4 imaging is a newer agent for imaging many malignancies with a good diagnostic value. We present a case of a young female diagnosed with left breast carcinoma in whom Ga-68 CXCR-4 PET/CT demonstrated tracer avid lesion in the nasopharynx. Biopsy of the nasopharyngeal lesion revealed Schminke type of lymphoepithelial cancer, indicating CXCR-4 PET/CT as a potential imaging modality for lymphoepithelial malignancy.

Cystic Parathyroid Adenomas: An Enigmatic Entity and Role of Tc-99 m Sestamibi Scintigraphy.

OBJECTIVE: Functional cystic lesion of the parathyroid gland is a rare cause of primary hyperparathyroidism (PHPT). They have been postulated to arise from the hemorrhage and cystic degeneration in the parathyroid adenoma (PA). We intended to analyze their scintigraphic and histopathological findings since available literature is sparse. METHODS: Dual-phase 99 mTc-sestamibi planar and SPECT/CT scans performed from January 2014 to January 2020 in patients presenting with PHPT were retrospectively analyzed. The clinical, biochemical, and ultrasound features were collected. Planar and SPECT/CT imaging parameters were analyzed. Detailed histopathological analysis, along with post-surgical clinical and biochemical features of the patients who underwent surgery, was reviewed with a mean follow-up of 21.8 ± 20.1 months. RESULTS: Of the 979 scans analyzed, 10 showed cystic parathyroid lesions (M:F- 3:7, mean age 45.6 ± 15 years, range: 23-66). The predominant presenting features in patients were abdominal pain and renal stone disease, present in 60% of the patients. On planar scintigraphy, 90% of the patients had tracer avid distinct lesions, whereas tracer activity was seen in the solid part of the cystic lesions in all 10 patients on SPECT/CT, with cystic areas showing an attenuation of 23.1 ± 7.6 HU. Eight of these patients underwent surgery, with all showing PA with cystic changes on histopathology. Two of these patients also showed hemorrhage within the cystic spaces. CONCLUSION: Hemorrhage within a PA may give rise to cystic parathyroid lesions with PHPT. 99 mTc-sestamibi scintigraphy with dual-phase imaging and SPECT/CT may help in detecting this rare entity.

Angiogenesis-Targeted 68Ga-DOTA-RGD2 PET/CT Imaging: a Potential Theranostic Application in the Case of Chondrosarcoma.

Chondrosarcoma is a cartilaginous tumor of mesenchymal origin. The histology and grade of the tumor determine the chances of relapse and survival. These tumors usually respond poorly to chemo-radiotherapy in cases of non-resectable and recurrent disease. 18F-FDG PET/CT has been used in evaluation of recurrence. However, these tumors show only mild to moderate FDG avidity due to their lower mitotic activity and large acellular matrix. These tumors are known to have a high degree of angiogenesis, especially in those of higher grade. We present a case of a 53-year-old man with grade II chondrosarcoma of the left femur showing only mild avidity on 18F-FDG PET/CT but showing moderate to intense tracer avidity on 68Ga-DOTA-RGD2 PET/CT. This may enable the use of angiogenesis-targeted positron and beta-emitting radiopharmaceuticals as a potentially new theranostic alternative treatment in cases of refractory metastatic chondrosarcoma.

Osteogenic Sarcoma Presenting with Skip, Lymph Nodal, Pulmonary, Pleural Metastases and Malignant Effusion: An Unusual Appearance on Bone Scan.

Osteogenic sarcoma is an aggressive malignant bone tumor arising from primitive mesenchymal bone-forming cells. Ossification is the characteristic feature of the metastases in osteosarcoma which aids their detection on 99mTc-MDP bone scintigraphy. Although lung is the most common site of metastasis in osteogenic sarcoma, pleural involvement with effusion and skip metastases are rare. Herein, we report a case of osteogenic sarcoma of distal femur with diffuse calcified pleural thickening leading to malignant pleural effusion, calcified lung, lymph node, and bone metastases illustrated on bone scan.

Infection imaging using [18F]FDG-labelled white blood cell positron emission tomography-computed tomography.

Localizing the sites of infection in the body is possible in nuclear medicine using a variety of radiopharmaceuticals that target different components of the infective and inflammatory cascade. Gamma(γ)-emitting agents such as [67Ga]gallium citrate were among the first tracers used, followed by development of positron-emitting tracers like 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG). Though these tracers are quite sensitive, they have limited specificity for infection due to their concentration in sites of non-infective inflammation. White blood cells (WBC) labelled with γ or positron emitters have higher accuracy for differentiating the infective processes from the non-infective conditions that may show positivity with tracers such as 18F-FDG. We present a pictorial review of potential clinical applications of PET/CT using 18F-FDG labelled WBC.

Follicular Thyroid Carcinoma with Unusual Radioiodine-Refractory Breast Metastasis Mimicking Primary Breast Malignancy.

The breast is an unusual site for metastasis from malignant tumors, although it may be the first manifestation of an extramammary primary malignancy typically arising in the lung, skin (melanoma), ovary, or lymph nodes (lymphoma). Breast metastasis from thyroid carcinoma is extremely rare and may take years to develop, as differentiated thyroid carcinoma is usually indolent and slow-growing and metastasizes to the lymph nodes, lungs, and bones. Here, we present the case of a middle-aged woman (after subtotal thyroidectomy for multinodular goiter 24 y previously) showing discordant 18F-FDG and iodine avidity in proven metastatic disease involving the lymph nodes, bones, spleen, and breast on whole-body 131I and 18F-FDG scans due to tumor heterogeneity.

Incremental Role of 18F-FDG-Labeled Autologous Leukocyte PET/CT in Suspected Postoperative Recurrence of Skull Base Osteomyelitis.

ABSTRACT: Skull base osteomyelitis is 1 of the complications of a middle ear infection seen mainly in immunocompromised individuals. A 3-phase bone scan and clinical, laboratory, and other radiological imaging are used for the diagnosis. However, in previously operated cases, bone scan findings are not reliable. We present a case of a 70-year-old man with persistent ear discharge postsurgery and with 3-phase bone scan negative for active infection. However, a subsequent 18F-FDG-labeled autologous leukocyte PET/CT study was able to diagnose the presence of active infection.

Ectopic Parathyroid Adenoma Mimicking as a Neuroendocrine Tumor on Ga68- DOTANOC Positron Emission Tomography/Computed Tomography Imaging.

Parathyroid adenoma sometimes present in ectopic location and may pose a difficulty in both diagnosis and localization. We report a case of a young lady suspected to have neuroendocrine tumor of the mediastinum demonstrating synaptophysin positivity on an initial core needle biopsy. Ga-68 DOTANOC positron emission tomography-computed tomography revealed a somatostatin receptor-expressing lesion in the anterior mediastinum with tracer avid multiple lytic bone lesions. On further biochemical and imaging workup with Tc-99 m SESTAMIBI, a diagnosis of ectopic parathyroid adenoma was made which was further confirmed with surgical excision.

Differentiating benign and malignant pancreatic masses: Ga-68 PSMA PET/CT as a new diagnostic avenue.

OBJECTIVE: Differentiation of malignant and benign pancreatic lesions on anatomical imaging is difficult in some cases with overlapping features. Prostate-specific membrane antigen (PSMA) is overexpressed during angioneogenesis in many tumors. We aimed to evaluate the PSMA expression in pancreatic lesions to differentiate these lesions and explore the performance of Ga-68 PSMA-PET/CT vis-a-vis F-18 FDG-PET/CT. METHODS: Patients with pancreatic lesions on conventional imaging were prospectively recruited. All the patients underwent a whole-body F-18 FDG-PET/CT and a regional abdominal Ga-68 PSMA-PET/CT. Focal tracer uptake (FDG or PSMA) on PET images was considered positive. Histopathology and/or cytopathology were considered the reference standard. RESULTS: A total of forty patients (27 males, mean age 55.3 ± 9.8, range 37-71 years) were enrolled. Of these, 19 were diagnosed as malignant on histopathology/cytology. Patients with benign lesions showed no worsening of symptoms for at least 6 months on follow-up. FDG-PET/CT revealed 17 true-positive (TP), 9 false-positive (FP), 12 true-negative (TN), and 2 false-negative (FN) findings, whereas PSMA-PET/CT had 18 TP, 2 FP, 19 TN, and 1 FN finding. The sensitivity, specificity, PPV, NPV, and accuracy for FDG-PET/CT were 89.5%, 57.1%, 65.4%, 85.7%, and 72.5%, respectively, while for PSMA-PET/CT were 94.7%, 90.5%, 90%, 95%, and 92.5%, respectively. ROC curve analysis showed that the SUVmax value of 4.8 on PSMA-PET/CT could predict the malignant potential of a lesion with a specificity of 90.5% and a sensitivity of 84.2%. CONCLUSIONS: Ga-68 PSMA-PET/CT imaging helped in establishing a non-invasive pre-operative diagnosis of primary pancreatic malignancy with a higher degree of specificity and accuracy compared with FDG-PET/CT. KEY POINTS: • Conventional imaging such as CT and MRI are unable to reliably differentiate localized malignant pancreatic lesion from benign lesions mimicking malignancy such as mass-forming pancreatitis. • FDG PET/CT helps in detecting malignant foci in view of their increased glucose metabolism. However, it may be falsely positive in inflammatory lesions which may occasionally hinder its ability to differentiate between benign and malignant lesions. • Apart from prostatic malignancy, PSMA is overexpressed in neovasculature of many non-prostatic malignancies. The present study highlights that Ga68 PSMA PET/CT performed better in diagnosing malignancy non-invasively than FDG-PET/CT with a higher PPV (90.5% vs. 65.4%) and accuracy (92.5% vs. 72.5%).