Diagnostic Performance of FAPI PET/CT vs. 18F-FDG PET/CT in Evaluation of Liver Tumors: A Systematic Review and Meta-analysis.

Objectives: Primary liver tumors constitute one of the most common tumors. These are aggressive tumors with poor survival. Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), most commonly used functional imaging, shows limited tracer retention and poor tumor to background ratios (TBR). Novel 68Ga-fibroblast-activation-protein inhibitor (FAPI) PET/CT has shown better tracer uptake and detection efficacy in liver tumors. However, most of the available literature is limited to single center studies with limited number of patients. So, we tried to review and analyze the head-to-head comparison of 18F-FDG PET/CT and 68Ga-FAPI PET/CT in evaluation of liver tumors. Methods: Literature available on head to head comparison of diagnostic accuracy of 18F-FDG PET/CT and 68Ga-FAPI PET/CT was searched in databases like PubMed, SCOPUS, EMBASE and Google Scholar for published original studies till April 2023. The relevant studies were selected and assessed using the Revised Tool for the Quality Assessment of Diagnostic Accuracy Studies-2 checklist. A random-effect model was used for calculating pooled sensitivity and specificity. They were represented with 95% confidence intervals (95% CI) and demonstrated in Forest plots. I-square statistic was used to assess heterogeneity in the studies. Results: Pooled sensitivity and specificity of FAPI PET/CT and 18F-FDG PET/CT for detection of primary liver tumors was 94.3% (95% CI: 90.6-96.8%); 89.3% (95% CI: 71.8-97.7%) and 56.1% (95% CI: 49.7-62.5%); 96.4% (95% CI: 81.7-99.9%) respectively. Pooled sensitivity for detection of extrahepatic metastatic disease was 92.2% (range: 88.1-100%; 95% CI: 87.8-95.4%) and 72.4% (range: 69.8-76.5; 95% CI: 65.9-78.2%) respectively. Also, the maximum standardized uptake value (SUVmax) and TBR were higher for FAPI PET/CT than 18F-FDG PET/CT in the included studies. Conclusion: Overall, FAPI PET/CT showed higher sensitivity for detection of liver tumors with better SUVmax and TBR than 18F-FDG PET/CT.

Potential of Liver Serum Enzymes and SUVmax in Primary Tumors as Predictive Biomarkers With Correlational Evidence.

Introduction Cancer exerts a substantial influence on the body's metabolism through varied mechanisms, instigating a metabolic reprogramming that maintains the unchecked growth and survival of cancer cells, consequently perturbing diverse metabolic parameters. The introduction of positron emission tomography-computed tomography (PET/CT), delivering detailed insights into both metabolic and morphological aspects, has brought about a revolutionary shift in modern cancer detection. Exploring the potential connection between PET-CT metabolic features and the metabolic parameters of liver enzymes in an individual can unveil novel avenues for cancer diagnosis and prognosis. Materials and methods This study conducted a retrospective analysis of patient records from our institution, covering the period from January 2021 to September 2023, focusing on individuals with various malignancies. The data included information on gender, age, clinical history, and liver serum parameters, which were compiled into tables. Additionally, inflammatory indicators such as ALT (alanine transaminase), ALP (alkaline phosphatase), total protein (TP), ALT/AST ratio, and SUVmax were collected and plotted. The study used Pearson correlation analysis to assess the relationship between each inflammatory variable and SUV (max) as determined by PET-CT. Results In breast cancer, there was a statistically significant positive correlation (R2=0.0651) between serum ALP levels and SUVmax as determined by regression analysis. Hodgkin lymphoma, on the other hand, showed a statistically significant negative correlation between the ALT-to-AST ratio (ALT/AST) and SUVmax (r = -0.45, R2 = 0.204). In non-Hodgkin lymphoma patients, total protein (TP) was negatively correlated with SUVmax (R2=-0.081, r= -0.28), while in lung cancer patients, there was a significant positive correlation with regression correlation coefficients (R2 = 0.026, 0.024, 0.024, and 0.018 for ALT/AST, TP, ALP, albumin, and ALT, respectively). Conclusion Aligning with these results, it can be a recent addition to acknowledge that both the tumor metabolic parameter (SUVmax) and the levels of liver serum enzymes exhibit a potential for predicting patient prognosis in various cancers.

Incidental 68Ga-PSMA Uptake in the Benign Enchondroma-A Rare Finding on 68Ga-PSMA PET/CT.

ABSTRACT: 68Ga-PSMA (prostate-specific membrane antigen)-HBED-CC (N,N'-bis[2-hydroxy-5-(carboxyethyl)benzyl]ethylenediamine-N,N'-diacetic acid) PET/CT is the new advancement in oncological imaging. However, false-positive uptake can be seen in benign lesions on 68Ga-PSMA PET/CT. We describe a rare case of intense 68Ga-PSMA uptake in an enchondroma confirmed on MRI.

Rare Case of Primary Leiomyosarcoma of Bone - Findings on 18F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography.

Primary leiomyosarcoma of bone (PLB) is a rare tumor, constituting <0.7% of all primary bone malignancies. It is clinically aggressive with heterogeneous presentation and a dismal prognosis. The most common presentation is pain with swelling and pathological fracture at times. Limited literature is available on PLB and only about 150 cases have been reported to date with only a few case reports defining the utility of 18F-fluorodeoxyglucose (18-F FDG) positron emission tomography/computed tomography (PET-CT) in its management. We hereby present a case of primary leiomyosarcoma of the right distal femur and the role of FDG-PET-CT in its management.

Radioiodine Uptake at Suture Site Granuloma Mimicking Neck Node Metastasis on 131 I Whole-Body Iodine Scintigraphy.

ABSTRACT: Differentiated thyroid carcinoma constitutes over 90% of all thyroid cancers. The standard treatment approach involves total or near-total thyroidectomy with or without neck dissection followed by 131 I whole-body scintigraphy (WBS) to detect local or distant metastases. Radioiodine offers high sensitivity and specificity for detection of metastatic disease in well differentiated thyroid carcinoma. However, despite its high accuracy, 131 I WBS demonstrates false-positive results, mostly at inflammatory or infective site. These false-positive radioiodine accumulation can lead to misdiagnosis and unwarranted radioiodine treatment. This case presents localization of 131 I to the suture site granuloma leading to false-positive results on 131 I WBS.

Incidental Detection of Myocardial Ischemia on Whole-Body PET/CT in a Patient With Carcinoma Lung.

ABSTRACT: 18 F-FDG PET/CT being a whole-body technique can detect multiple other critical nononcological findings. Various cardiac disorders identified incidentally on 18 F-FDG have been reported to help in timely management and improve overall patient care. We hereby present one such case where 18 F-FDG PET/CT performed for a workup of carcinoma lung revealed abnormal myocardial FDG uptake in the anteroseptal and apical region, which raised suspicion of myocardial ischemia such as hot spot imaging. On coronary angiography, coronary artery disease was detected and subsequently managed.

Role of PSMA-targeted PET-CT in renal cell carcinoma: a systematic review and meta-analysis.

Fluoro-deoxy glucose positron emission tomography/computed tomography (PET/CT), the workhorse of nuclear medicine, has limited utility for renal cell carcinoma (RCC), particularly clear cell variant. Thus, various other tracers have been tried for evaluation of RCC. One of the most promising targets for radiotracers is prostate-specific membrane antigen (PSMA) expressed in abundance in carcinoma-associated neo-vasculature. Thus, we tried to review and analyse the role of PSMA-targeted PET/CT in evaluation of RCC. Databases like PubMed, EMBASE and SCOPUS were searched for original studies published on PSMA-targeted PET/CT in RCC till 30 September 2023. Revised Tool for the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) checklist was used to assess the included studies. Pooled sensitivity and specificity were calculated and represented with 95% confidence intervals (95%CI). Heterogeneity in the studies was assessed by I-square index. Pooled sensitivity and specificity of PSMA-targeted PET/CT for detection of local disease estimates were 87.2% (95%CI: 77-94%) and 100% (95%CI: 92.9-100%), respectively. Pooled sensitivity and specificity for detection of local recurrent disease are 100% (95%CI: 71.5-100%) and 100% (95%CI: 89.4-100%), respectively. Pooled sensitivity and specificity for detection of metastatic disease are 92% (95%CI: 86.2-96%) and 96.9% (95%CI: 83.8-99.9%), respectively. Pooled sensitivity of PSMA-targeted PET/CT for detection of clear cell renal cell carcinoma (ccRCC) and non-ccRCC are 94.7% (95%CI: 88-98.3%) and 75% (95%CI: 35-96.8%), respectively. PSMA-targeted PET-CT demonstrated better diagnostic efficacy for the detection of recurrent RCC. Whilst for staging RCC, it had higher specificity but lower sensitivity. Thus, it can serve as a non-invasive adjuvant tool to conventional imaging in the evaluation of staging of RCC, particularly clear cell variant.

False-Positive Radioiodine Uptake in the Cervix in a Patient with Thyroid Cancer.

Radioactive iodine (RAI) accumulation is commonly used for the detection of metastatic disease posttotal thyroidectomy. However, false-positive results have been reported due to abnormal RAI accumulation in some benign pathologies apart from metastatic sites. Here, we present one such case where false-positive I-131 uptake in the pelvis which localized to the cervix and was attributed to menstruation.

Delayed Recurrence of Gall Bladder Cancer as Port-site Metastases with Occult Primary Detected on Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography: A Tale of Two Cases.

Laparoscopic cholecystectomy is a fairly common procedure and is currently considered the gold standard for cholecystectomy. However, the laparoscopic procedure in the presence of gall bladder cancer (GBC) is associated with the risk of port-site metastasis (PSM). Furthermore, in few cases, GBC remains occult even on postoperative histopathology and presents with PSM remotely. Here, we describe two such cases of GBC with occult primary who presented with PSM and also defined the role of fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography in the management of such cases.

Uterine Metastasis Presenting as Abnormal Uterine Bleeding in a Case of Primary Breast Cancer Identified on 18F-FDG PET/CT.

Metastases to the female genital tract are rare, especially from extragenital primaries. The most common extragenital sites associated with genital metastasis are the gastrointestinal tract (37.6%) followed by the breast (34.9%). It is crucial to differentiate primary from metastatic involvement of the uterus for appropriate patient management. We present one such case of endometrial metastasis in a patient who presented clinically with abnormal uterine bleeding and was diagnosed with primary breast cancer via 18F-FDG PET/CT.

Recurrent Renal Cell Carcinoma Presenting as Port-Site Metastases, Detected on 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography.

The incidence of port-site metastases (PSMs) varies with the tumor type with adenocarcinoma having a high incidence. However, it is rarely seen in urological malignancies and more so in renal cell carcinoma (RCC). We hereby describe one such case of PSM after laparoscopic radical nephrectomy for RCC, which was detected on 18F-fluorodeoxyglucose positron emission tomography-computed tomography.

Small Chyle Leak Localized on Lymphoscintigraphy with Single-Photon Emission Computed Tomography-Computed Tomography.

Chylothorax refers to the accumulation of triglyceride-rich fluid (chyle) within the pleural space. We described a case of spontaneous chylothorax in an infant. Lymphoscintigraphy was performed with 99 m-Tc sulfur colloid which showed tracer accumulation into thoracic cavity, and single-photon emission computed tomography/CT (SPECT/CT) revealed leak in the thoracic duct at D8 vertebral level as the cause. We, thus, emphasize the role of lymphoscintigraphy with SPECT/CT in identification of cause and guiding the management of chylothorax, especially when surgical treatment is planned.

Efficacy and Safety of Actinium-225 Prostate-Specific Membrane Antigen Radioligand Therapy in Metastatic Prostate Cancer: A Systematic Review and Metanalysis.

BACKGROUND: Actinium-225 (Ac-225) labelled PSMA RLT has been tested recently in metastatic castration-resistant prostate cancer (mCRPC), with encouraging results. Ac-225, being an alpha emitter, is expected to have higher efficacy and fewer side effects compared to the beta-emitters such as Lutetium-177. We have performed a meta-analysis to assess the therapeutic responses, survival effects, and significant side effects of Ac-225 PSMA RLT in patients with mCRPC. METHODOLOGY: Systematic literature search was carried out from five electronic databases PubMed/MEDLINE, SCOPUS, EMBASE, Web of Science, and Cochrane Library until March 2021. Eight studies were found to be eligible for this metanalysis. RESULTS: Eight studies with 226 patients were analyzed in this metanalysis. 81% (95% CI 73-89) patients had a decline in PSA levels. 60% of the patients showed more than 50% PSA decline. Two studies assessed survival effects of radioligand naïve patients compared to patients who had received Lu-PSMA therapy previously and the pooled HR for radioligand naïve patients is 0.22. The most common toxicity reported was xerostomia in 167 patients out of 226 patients (73.9%, 95% CI 67.6-79.5%); however, most of them were confined to grade I and II levels. Other reported side effects include hematologic toxicity and nephrotoxicity. CONCLUSION: Ac-PSMA RLT is a safe and potentially effective treatment option for patients with mCRPC.

Steroid-Induced Activated White Adipose Tissue Detected on 18F-FDG PET/CT.

White adipose tissue (WAT) usually shows negligible 18F-FDG uptake due to negligible glucose utilization. However, corticosteroids alter the biodistribution of 18F-FDG and increase uptake in WAT. Here, we present a case of diffusely increased 18F-FDG uptake in WAT secondary to high-dose corticosteroid therapy for nephrotic syndrome.

Acute Myeloid Leukemia following Radioactive Iodine Therapy for Metastatic Follicular Carcinoma of the Thyroid.

Radioactive iodine (RAI) therapy is widely used and has an important role in the management of hyperthyroidism and thyroid malignancies. The development of acute or chronic leukemia is a very rare complication of RAI therapy. We report a case of metastatic Follicular thyroid cancer (FTC) who underwent total thyroidectomy followed by treatment with a cumulative dose of 1600 mCi of RAI (for 4 years) and by palliative radiotherapy for L4 spinal metastasis, later on, developed acute myeloid leukemia. Thus, all patients with thyroid carcinoma treated with RAI should undergo periodic hematological examinations irrespective of RAI dose.

Study of Correlation between Serum Osteoprotegerin, TNF-Alfa, and Biomarkers of Bone Metabolism in Patients with Treatment-Naive Graves' Disease-A Cross-Sectional Study.

Objectives: Primary - a study of the correlation between serum osteoprotegerin (OPG), and biomarkers of bone metabolism in patients with treatment-naive Graves' disease (GD). Secondary - serum level of OPG, TNF-alfa, and biomarkers of bone metabolism in patients three months after treatment of GD with methimazole (MMI). Materials and Methods: A total of thirty-five treatment-naive newly diagnosed GDs were recruited for the study, most of them female. All patients started with MMI for treatment and various blood parameters were measured at baseline and three months after treatment. Measurements: Serum calcium (Ca), phosphorus (P), bone-specific alkaline phosphatase (B-ALP), OPG, TNF-alfa, and urine deoxypyridinoline (U-DPD) along with serum-free T3 and T4, thyroid-stimulating hormone (TSH) and thyroid receptor antibody (TR-ab) were analysed at baseline and three months after MMI treatment. All the patients had euthyroid at three months of MMI treatment. Results: Mean serum OPG (0.94 ± 1.39 vs. 0.63 ± 0.27 ng/ml; P = 0.262) level at baseline and after treatment with MMI did not show any significant change. Mean TSH level (0.207 ± 0.59 vs. 1.00 ± 1.95, P = 0.025) was significantly low at baseline than after treatment; FT4 (5.9 ± 5.22 v 1.77 ± 1.89 ng/dl; P < 0.001), FT3 (12.19 ± 6.91 vs. 4.99 ± 3.55 pg/ml; P < 0.001), and TNF-alfa values decreased significantly after treatment, however, PTH (58.09 ± 28.75 vs. 75.57 ± 41.50; P < 0.026) increased significantly after treatment. Discussion: There is no correlation of OPG with thyroid hormone profile, TSH, thyroid receptor antibody (TR-ab), and bone metabolic parameters such as serum Ca, P, B-ALP, TNF-alfa, and U-DPD in our study. Mean TNF-alfa decreased significantly (393.43 ± 270.473 vs. 139.34 ± 101.264 pg/ml; P = 0.001) level after treatment with MMI. TNF-alfa was positively correlated with TR-ab (r = 0.374; P = 0.027) and B-ALP (r = 0.388; P = 0.021). Conclusion: The bone turnover marker in GD seems to be mediated other than OPG. We observed an increase in circulating TNF-alfa in GD with a significant decrease after treatment. TNF-alfa could be a marker of GD activity as evidenced by a close positive correlation with TR-ab, a sensitive marker of GD autoimmunity. TNF-alfa could be a factor associated with bone turnover markers in GD despite its euthyroid state.

Rare Case of Phyllodes Tumor of Breast with Cardiac and Pancreatic Metastases: Findings on 18F-FDG PET/CT.

Phyllodes tumor (PT) represents a rare type of breast tumor arising from the stromal component rather than the epithelium. Metastatic spread occurs hematogenously, with lung, bone, brain, and liver being the most common sites. We present the 18F-FDG PET/CT scan of one such case of phyllodes tumor showing cardiac and pancreatic metastases, which are an extremely rare occurrence.

An Incidentally Detected Case of Atypical Bronchial Carcinoid on Stress Myocardial Perfusion SPECT/CT.

Myocardial perfusion imaging is primarily done to look for stress-induced perfusion defects in patients suspected of having coronary artery disease. However, the rotating raw images can provide significant information on the surrounding structures. The lungs lie near the heart, and any abnormality showing increased uptake can be seen on myocardial perfusion imaging. We report the case of a 52-y-old man with a history of diabetes for the previous 5 y, who presented to the cardiology outpatient department because of occasional chest pain and dyspnea. Electrocardiography and echocardiography showed no significant abnormality. The patient was referred to the nuclear medicine department for stress-induced myocardial perfusion scintigraphy. The raw 99mTc-sestamibi images showed abnormal uptake in the hilar region of the right lung, which, on subsequent investigations, was diagnosed as atypical bronchial carcinoid tumor.

Aberrant Radioactive Iodine Uptake in Simple Ovarian Cyst: A Rare Finding.

I-131 whole body scan and therapy play an important role in the follow-up of differentiated thyroid carcinoma patients for the detection of residual thyroid tissue and metastatic disease. However, various false-positive findings have been reported in the literature which can appear as metastases. Here, we present one such case, in which an I-131 posttherapy scan revealed false-positive radioactive iodine uptake which localized to a simple ovarian cyst.