Deepanksha Datta

Autoimmune encephalitis usually presents with short‐duration neuropsychiatric syndromes, mainly behavioral with cognitive dysfunction, recurrent seizures, and movement disorders. Among them, anti‐LGI1 encephalitis has faciobrachial dystonic seizure as a pathognomic feature. The two cases reported here exemplify another peculiar feature of anti‐LGI1 encephalitis, which has rarely been reported and is therefore not typically emphasized. Both cases were initially treated for cardiac symptoms until the full‐blown features of encephalitis became evident. The key to preventing adverse outcomes is early detection, as anti‐LGI1 encephalitis is largely reversible when treated early with immunotherapy, whereas a delay in diagnosis can lead to permanent damage or fatal outcomes.

Intratumoral heterogeneity is a primary driver of treatment resistance in many malignancies, including esophageal cancer. While Fluorine-18 Fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) is a standard tool for staging and response assessment in the esophageal malignancy, the qualitative visual assessment of primary tumor and metastases is limited by interobserver variability. The purpose of this study is to determine if the non-invasive imaging biomarkers on F-18 FDG PET can reliably distinguish the two primary histological subtypes of esophageal malignancy namely squamous cell carcinoma (SCC) and adenocarcinoma (AC). This is a retrospective study approved by the institutional ethical committee, and conducted in histopathologically proven cases of esophageal malignancy of either squamous cell or AC subtypes, who underwent baseline staging F-18 FDG PET/CT as per the standard guidelines. The metabolic parameters namely tumoral maximum standardized uptake value (SUVmax), total lesional glycolysis (TLG), metabolic tumor volume (MTV) and metabolic ratio of tumor to liver (standardized uptake ratio [SUR]) were calculated and compared between the two histological subtypes using Mann − Whitney U test. A p-value of less than 0.05 was considered statistically significant. Out of 59 patients (M:F = 33:26) included in the study, 40 had squamous cell subtype and 19 had AC. Median age was 57 years (range: 30–83), and the median SUVmax, SUR, MTV, and TLG of AC group was 10.89 g/mL, 3.86, 9.98 mL, and 55.8 g/mL, while that of squamous group was 13.88 g/mL, 5.6, 13.52 mL, and 108.4 g/mL, respectively. There was significant difference noted in the tumoral SUVmax (p = 0.043), SUR (p = 0.019), and TLG (p = 0.032) between the two groups, with higher metabolic values observed in the squamous group. MTV (p = 0.224) between the two groups was insignificant. This study demonstrates that quantitative parameters on F-18 FDG PET are effective non-invasive biomarkers for differentiating the histological subtypes of esophageal malignancy. The squamous cell subtype exhibits significantly higher metabolism and total lesion glycolysis than AC.

Purpose: ¹⁸ F fluoro 2-deoxy-D-glucose (FDG) uptake in positron emission tomography/computed tomography (PET/CT) scans is commonly observed in the brain, myocardium, liver, intestines, and excretory pathways such as kidneys and the urinary bladder. This study examines the incidence and contributing factors for physiological FDG accumulation in the gallbladder (GB) lumen, in the absence of clinical history or anatomical abnormalities. Materials and Methods: This retrospective study was conducted at a North Indian tertiary care hospital on patients who underwent ¹⁸ F FDG PET/CT between January and August 2024. The study group included individuals with GB intraluminal FDG uptake exceeding blood pool levels without anatomical changes, while the control group comprised patients without GB uptake. Comparisons were made based on body mass index, fasting blood sugar, FDG dose, time-to-scan interval, and SUVmax (standardized uptake value). Mann–Whitney U -test was employed for statistical analysis. Results: Among 632 screened patients, 82 (13%) exhibited GB FDG uptake, whereas 149 were randomly selected for the control group. The study group showed significantly higher fasting blood sugar (101 [24] vs. 93 [18] mg/dl, P = 0.007), FDG dose (6.8 [2.5] vs. 6 [2.3] mCi, P < 0.001), and longer time to scan (82 [54] vs. 78 [38] min, P = 0.02). The median SUVmax for GB uptake was 2.1 (0.93) g/ml. Conclusion: Physiological GB FDG uptake occurs in about 13% of patients. Increased fasting blood sugar, higher FDG dose, and prolonged scan intervals elevate the likelihood of GB uptake.

Purpose This review aimed to evaluate the diagnostic performance of Neck Imaging Reporting and Data System (NIRADS) categories using 2-deoxy 2-(Fluorine-18) fluoro D-glucose positron emission tomography integrated with computed tomography (F-18 FDG PET/CT) to diagnose recurrence or treatment failure in the post-treatment assessment of head and neck squamous cell carcinoma (HNSCC). Methods A systematic search of the indexed medical literature was conducted till 7 November 2024 using PubMed, Scopus, Cochrane Library and Google Scholar to include studies reporting post-treatment recurrence rates on F-18-FDG PET/CT as per the NIRADS criteria. Studies were qualitatively assessed for risk of bias using the QUADAS-2 tool. We categorized patients with ‘NI-RADS≤2’ as low risk of recurrence and ’NI-RADS ≥3’ as high risk of recurrence. Diagnostic performance of NI-RADS was evaluated through weighted-pooling of standard metrics of diagnostic accuracy, diagnostic Odd’s ratio (DOR) and summary receiver operator characteristic (SROC) curve analysis. Results Out of 1632 records identified, 8 studies with 7 datasets were included, with over 1200 patients and over 1300 F-18 FDG PET/CT scans. All studies were retrospective, with presence of a risk for bias, publication bias and data heterogeneity. The time between treatment and F-18 FDG PET/CT assessment was 8–17 weeks. For combined sites (primary, nodal or distant sites), the ability of ’NIRADS ≥3’ over ‘NIRADS ≤2’ to detect a recurrence was acceptable with a pooled sensitivity, specificity, positive and negative likelihood ratios of 0.68 (95% Confidence Interval, CI 0.63–0.73), 0.90 (95% CI, 0.88–0.92), 6.01 (95% CI, 2.9– 12.6) and 0.47 (95% CI, 0.31– 0.71) respectively, with a DOR of 14.13 (95% CI, 9.78–20.42) and an area under the curve, AUC of 0.859 (Standard Error, SE -0.018) on SROC analysis Conclusion In F-18 FDG PET/CT done on post-treatment HNSCC patients, the diagnostic performance of NIRADS ≥3 categories over NIRADS ≤ 2 categories in detecting treatment failure or recurrence at combined primary, nodal or distant sites was acceptable, with a low certainty of evidence. The NIRADS categories, especially NIRADS ≥3 and NIRADS ≤2 categories should be routinely reported in post-treatment F-18 FDG PET/CT scans in HNSCC patients. (No funding received; PROSPERO No. CRD42022376017)

Background: The proliferation index (Ki-67 index) is a known independent prognostic marker in carcinoma breast, and its expression is directly proportional to higher recurrence and worse prognosis. However, there is no standard cutoff of the Ki-67 index to determine its low or high expression. In this study, we aim to find the association of various metabolic parameters on ¹⁸ F FDG positron emission tomography/computed tomography (PET/CT) with Ki-67 index in carcinoma breast patients and further evaluate its correlation with low and high Ki-67 index groups. Materials and Methods: This is a retrospective study conducted in a tertiary hospital in North India between February 2021 and 2024. All histopathologically proven female cases of carcinoma breast with reported Ki-67 index and baseline ¹⁸ F FDG PET/CT before any treatment or surgery were included. The metabolic parameters, namely, standardized uptake value (SUVmax), the metabolic ratio of the primary tumor to the liver (SUR), total lesion glycolysis (TLG), and metabolic tumor volume (MTV) were recorded for each case. The correlation between the metabolic parameters and the Ki-67 index was analyzed, and subgroup analysis was done. Results: Sixty-five female patients met the inclusion criteria, and the majority of them presented with intraductal carcinoma. The median value (interquartile range [IQR]) of the Ki-67 index was 40% (IQR: 50%). The primary breast tumor showed median (IQR) of SUVmax, SUR, TLG, and MTV of 10.3 g/mL (7.2), 3.7 (2.9), 102.9 g.cub/mL (184.7), and 16.2 cm ³ (25.4), respectively. A significant correlation was noted between all the metabolic parameters studied and the Ki-67 index. In subgroup analysis, a significant difference was noted in all the metabolic parameters between the subgroups of the Ki-67 index ≤25% versus >25%. Conclusion: Metabolic parameters on ¹⁸ F FDG PET/CT show a promising role in the determination of the status of proliferation marker Ki-67 index in carcinoma breast.

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.

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.

Paraneoplastic neurological syndrome (PNS) represents a rare group of central nervous system disorders that are unrelated to direct tumor invasion or metastasis but may be triggered by an immune system reaction to a neoplasm or malignant tumor. In many patients, PNS is diagnosed before identifying the primary cancer. In such instances, positron emission tomography/computed tomography scan can assess individuals with suspected PNS enabling the detection of hidden malignancies. We share an interesting image of paraneoplastic cerebellar degeneration in a case of invasive ductal carcinoma breast.

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.

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.