18FDG PET/CT imaging of adenovirus-associated acute interstitial nephritis after allogeneic bone marrow transplantation.

Adenovirus-associated acute interstitial nephritis (AAIN) should always be considered in the differential diagnosis of acute kidney failure following allogeneic bone marrow transplant. Although not intended for the definitive diagnosis of AAIN, 18FDG PET/CT can be a helpful noninvasive diagnostic tool, especially when a biopsy is not feasible.

Warthin's Tumour as a Parotid Gland Incidentaloma Identified by PET-CT Scan in a Large Series of Cases.

Occasionally in imaging scans there are findings unrelated to the pathology for which the scan was indicated, findings that are called incidentalomas. Warthin tumors have a high glucose avidity, being one of the common incidentalomas in PET-CT scans. The aim of the present study is to analyze the frequency of occurrence of Warthin's tumor as an incidental finding in a large series of patients undergoing 18F-FDG PET-CT. Retrospective analysis of 18F-FDG PET-CT scans performed in our center during the period 2010-2021. Parotid hypermetabolic lesions were identified, as well as their SUVmax, size, smoking habit, BMI (body mass index), and otorhinolaryngology follow-up. 31,423 PET-CT-18FDG studies corresponding to 12,806 patients were analyzed. The frequency of incidentalomas at the parotid level with a diagnosis compatible with Warthin's tumor was 0.87% (n = 111). Eighty percent of the patients with incidentalomas accordant to Warthin's tumor had a history of tobacco use. The highest percentage of incidentalomas compatible with a Warthin tumor was found in patients in whom the indication for PET-CT was the study of a lung carcinoma (1.44%). Only 37% of patients with a PET-CT lesion compatible with a Warthin's tumor were referred for evaluation by the Otorhinolaryngology service. The incidence of Warthin's tumor in 18-FDG PET-CT scans in our center was 0.87%.

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.

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.

Diagnostic Performance of F-18 FDG PET/CT in the Detection of Recurrent Colorectal Cancer: Correlation with Biochemical Markers and Conventional Imaging Modalities.

Background/Objectives: Although the role of PET/CT imaging is well established in oncology, its diagnostic value in routine monitoring for recurrent colorectal cancer (CRC) is still controversial. The aim was to evaluate the diagnostic value of F-18 FDG PET/CT in detecting recurrent CRC in correlation with CEA, CA 19-9 levels, and conventional imaging modalities (CIM). Methods: Between 2009 and 2023, a retrospective study was performed including 134 CRC patients referred for PET/CT imaging on the suspicion of recurrence, based on elevated CEA and/or CA 19-9 and/or equivocal CIM findings. According to our institution's Tumor Board CRC protocol, after the initial treatment, which was dependent on the TNM stage (neoadjuvant therapy, primary resection, or adjuvant treatment), patients underwent a standard 5-year surveillance including CEA and CA 19-9 measurements, CIM, and colonoscopy, every six months. The statistics, including univariate and multivariate analyses were conducted using the IBM SPSS 20.0 statistical software. p-values < 0.05 were considered statistically significant. Results: Recurrent CRC was confirmed in 54/134 (40.3%) patients with elevated tumor markers. PET/CT showed high diagnostic performance in detecting recurrent CRC with sensitivity, specificity, PPV, NPV, and accuracy of 94.4%, 82.5%, 78.5%, 95.7%, and 87.3%, respectively. The CEA showed a high sensitivity of 98.1% but both low specificity and accuracy of 15% and 48.5%, respectively. The sensitivity, specificity, and accuracy for CA 19-9 and CIM for diagnosis of CRC recurrence were 44.4%, 67.5%, 58.2%, and 51.9%, 98.8%, 79.9%, respectively. The AUC for PET/CT, elevated CEA levels, CIM, and elevated CA 19-9 levels was 0.885 (95% CI: 0.824-0.946; p < 0.001), 0.844 (95% CI: 0.772-0.916; p < 0.001), 0.753 (95% CI: 0.612-0.844; p < 0.001), and 0.547 (95% CI: 0.442-0.652; p = 0.358), respectively. Univariate analysis showed that both PET/CT and CIM positive results were highly associated with CRC recurrence (p < 0.001 and p < 0.001, respectively). At the same time, gender, mucinous tumor type, presence of initial lymph node metastasis (N+), and presence of initial distant metastasis (M+) had no significance (p = 0.211, p = 0.158, p = 0.583, and p = 0.201, respectively). Our multivariate analysis showed that independent predictors for CRC recurrence are positive PET/CT scans (p < 0.001), positive CIM results (p = 0.001), and elevated CA 19-9 levels (p = 0.023). Although CA 19-9 was not detected as a statistically significant predictor in the univariate analysis (p = 0.358), in a multivariate analysis it was recognized as a significant predicting factor in detecting the CRC recurrence (p = 0.023). Conclusions: F-18 FDG PET/CT showed high diagnostic efficacy in CRC recurrence detection, in correlation with CEA levels, CA 19-9 levels, and CIM. This imaging modality should be routinely integrated into the post-operative follow-op in patients with elevated tumor markers.

18F-Fluorodeoxyglucose-Avid Benign Anthracotic Mediastinal Lymphadenitis Mimicking Metastatic Lymphadenopathy.

The staging of malignancy is critical for its effective management. 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) imaging is a common modality for malignancy staging, which identifies areas of FDG avidity. However, multiple benign etiologies can cause false-positive 18F FDG-avid nodes. Among these, extrapulmonary involvement of anthracosis in the form of lymphadenopathy is a rare entity. In patients with concomitant malignancies, the presence of 18F FDG-avid anthracotic lymph nodal enlargement may mimic nodal metastasis. Endosonography-guided tissue acquisition may help differentiate between the two. Herein, we describe six cases of FDG-avid benign anthracotic lymphadenitis detected during staging workups for patients with malignancies who later underwent curative resection.

Incidental finding of Psuedomyxoma Peritonei in Malignant Peripheral Nerve Sheath Tumour.

Psuedomyxoma peritonei is an infrequent clinical entity characterised by intraperitoneal mucinous/gelatinous ascites produced by the cancerous cells. It has been associated with gastrointestinal, gynaecological, lung and breast tumours. It is commonly asymptomatic and is most often detected incidentally on abdominopelvic imaging or laparoscopy. Higher histological grade of the tumour shows increased metabolic activity on 18F-Fluorodeoxyglucose (FDG) positron-emission tomography (PET) computed tomography (CT). It has been rarely reported in patients with sarcoma. We hereby present an interesting case of incidentally diagnosed pseudomyxoma peritonei on 18FDG PET-CT scan of a patient with soft tissue sarcoma of peripheral nerve sheath.

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.

The Additional Role of F18-FDG PET/CT in Characterizing MRI-Diagnosed Tumor Deposits in Locally Advanced Rectal Cancer.

Rationale: F18-FDG PET/CT may be helpful in baseline staging of patients with high-risk LARC presenting with vascular tumor deposits (TDs), in addition to standard pelvic MRI and CT staging. Methods: All patients with locally advanced rectal cancer that had TDs on their baseline MRI of the pelvis and had a baseline F18-FDG PET/CT between May 2016 and December 2020 were included in this retrospective study. TDs as well as lymph nodes identified on pelvic MRI were correlated to the corresponding nodular structures on a standard F18-FDG PET/CT, including measurements of nodular SUVmax and SUVmean. In addition, the effects of partial volume and spill-in on SUV measurements were studied. Results: A total number of 62 patients were included, in which 198 TDs were identified as well as 106 lymph nodes (both normal and metastatic). After ruling out partial volume effects and spill-in, 23 nodular structures remained that allowed for reliable measurement of SUVmax: 19 TDs and 4 LNs. The median SUVmax between TDs and LNs was not significantly different (p = 0.096): 4.6 (range 0.8 to 11.3) versus 2.8 (range 1.9 to 3.9). For the median SUVmean, there was a trend towards a significant difference (p = 0.08): 3.9 (range 0.7 to 7.8) versus 2.3 (range 1.5 to 3.4). Most nodular structures showing either an SUVmax or SUVmean ≥ 4 were characterized as TDs on MRI, while only two were characterized as LNs. Conclusions: SUV measurements may help in separating TDs from lymph node metastases or normal lymph nodes in patients with high-risk LARC.

Overview of F18-FDG uptake patterns in retroperitoneal pathologies: imaging findings, pitfalls, and artifacts.

INTRODUCTION: Retroperitoneum can be the origin of a wide variety of pathologic conditions and potential space for disease spread to other compartments of the abdomen and pelvis. Computed tomography (CT) and magnetic resonance imaging (MRI) are often the initial imaging modalities to evaluate the retroperitoneal pathologies, however given the intrinsic limitations, F18-FDG PET/CT provides additional valuable metabolic information which can change the patient management and clinical outcomes. We highlight the features of retroperitoneal pathologies on F18-FDG PET/CT and the commonly encountered imaging artifacts and pitfalls. The aim of this review is to characterize primary and secondary retroperitoneal pathologies based on their metabolic features, and correlate PET findings with anatomic imaging. CONCLUSION: Retroperitoneal pathologies can be complex, ranging from oncologic to a spectrum of non-oncologic disorders. While crosse-sectional imaging (CT and MRI) are often the initial imaging modalities to localize and characterize pathologies, metabolic information provided by F18-FDG PET/CT can change the management and clinical outcome in many cases.

Prognostic implications of response to neoadjuvant chemotherapy in breast cancer subtypes.

The current study was designed to assess the response to treatment, as well as clinical and survival outcomes, across different breast cancer subtypes in patients who underwent neoadjuvant chemotherapy (NAC). From 2014 to 2019, a total of 139 patients who were histologically confirmed to have breast cancer, underwent NAC, and subsequently received breast and axillary surgery, were retrospectively included in this study. The rates of pathological complete response (pCR) to NAC were significantly higher for HER2-positive and triple-negative subtypes than for luminal A and HER2-negative subtypes (p = 0.013). Multivariate analysis for disease-free survival (DFS) revealed that tumour grade and the presence of pCR were independent prognostic factors. The presence or absence of a pCR with NAC was an independent prognostic indicator in the multivariate analysis for overall survival (OS). Lastly, achieving a pCR was independently predicted by 18F-FDG PET/CT findings, the HER2-positive subtype, and the triple-negative subtype. Despite the inherent methodological limitations, our findings underscore the significance of identifying predictive markers to tailor NAC plans, with the aim of improving survival outcomes.

Usefulness of 18F-FDG PET-CT in the Management of Febrile Neutropenia: A Retrospective Cohort from a Tertiary University Hospital and a Systematic Review.

Febrile neutropenia (FN) is a complication of hematologic malignancy therapy. An early diagnosis would allow optimization of antimicrobials. The 18F-FDG-PET-CT may be useful; however, its role is not well established. We analyzed retrospectively patients with hematological malignancies who underwent 18F-FDG-PET-CT as part of FN management in our university hospital and compared with conventional imaging. In addition, we performed a systematic review of the literature assessing the usefulness of 18F-FDG-PET-CT in FN. A total of 24 cases of FN underwent 18F-FDG-PET-CT. In addition, 92% had conventional CT. In 5/24 episodes (21%), the fever was of infectious etiology: two were bacterial, two were fungal, and one was parasitic. When compared with conventional imaging, 18F-FDG-PET-CT had an added value in 20 cases (83%): it diagnosed a new site of infection in 4 patients (17%), excluded infection in 16 (67%), and helped modify antimicrobials in 16 (67%). Antimicrobials could be discontinued in 10 (41.6%). We identified seven publications of low quality and one randomized trial. Our results support those of the literature. The available data suggest that 18F-FDG-PET-CT is useful in the management of FN, especially to diagnose fungal infections and rationalize antimicrobials. This review points out the low level of evidence and indicates the gaps in knowledge.

Gamma delta lymphoma: a pictorial review of F-18 fluorodeoxyglucose PET/CT findings and a brief review of the literature.

Gamma Delta (γδ) T-cell lymphomas are uncommon and aggressive neoplasms originating from the γδ receptor-bearing lymphocytes. The most frequent entities include primary hepatosplenic γδ T-cell lymphomas, primary cutaneous γδ lymphoma, and monomorphic epitheliotropic T-cell lymphoma. F-18 fluorodeoxyglucose (FDG) PET/CT is an important modality in the staging of Hodgkin's and various non-Hodgkin's lymphoma. However, literature is scare on imaging findings of γδ lymphoma on F-18 FDG PET/CT. In this review, we discuss briefly the clinical and biological features and present the spectrum of F-18 FDG PET/CT findings of γδ lymphoma.

Evaluation of blood supply and metabolism in tumor, axillary lymph node and normal breast tissue with F-18 FDG PET/CT in breast cancer: comparison with pathological prognostic factors.

BACKGROUND AND PURPOSE: Perfusion parameters obtained in F-18 FDG PET/CT performed for staging purposes in breast cancers may provide additional information about tumor biology as well as glucose metabolism. The aim of this study was to evaluate throughout F-18 FDG PET/CT the relationship between blood flow and glucose metabolism and histological parameters of the primary tumor, normal mammary gland, and axillary lymph nodes in breast cancer patients. MATERIALS AND METHODS: Sixty six female patients (mean age 51 y ± 12,81) were prospectively included to this study. We performed dynamic blood flow (f) study that started with 296-444 MBq (8-12 mCi) F-18 FDG injection and lasted for 10 minutes, and glucose metabolism (m) imaging one hour later. On each frame, mean activity concentration (AC) values (Bq/mL) were recorded on a spherical volume of interest (VOI) having a volume of ~ 1 cm3 on the hottest voxel of primary tumor (T), across normal breast gland (NG) and ipsilaterally axillary lymph nodes (iLN). Correlations among PET parameters and estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (c-erbB2) and Ki67 index were analyzed. RESULTS: T volume (TV) ranged from 1.1 to 85.28 cm3 [median (IR): 6.44 (11.78)]. There were positive correlations between c-erbB2 and TACf and between c-erbB2 and iLNACf (p = 0.045, r = + 0.248; p = 0.050, r = + 0.242). In the ER positive (ERP) patients, TV and TACm were significantly lower than those of ER negative (ERN) (respectively p = 0.044 and p = 0.041). In patients with two positive Ki-67 indices, iLN-SUVmax was significantly higher than one-positive patients (p = 0.020). There was a negative correlation between NGACm and histological grade of tumor (p = 0.005, r = - 0.365). CONCLUSIONS: Breast cancer shows differences in progression, metastasis and survival due to its diversity in terms of molecular, biological and angiogenesis. High glucose metabolism in breast cancers is associated with tumor aggressiveness. Being able to examine tumor tissue characteristics such as blood flow and glucose metabolism with a single diagnostic technique and to reveal its relationship with histological parameters can provide a reliable pretherapeutic evaluation in breast cancers.

Prognostic Value of Serum Neutrophil to Lymphocyte Ratio and SUVmax in Stage I and II Colon Cancer.

OBJECTIVE: This study aimed to evaluate the correlation between maximal standardized uptake value (SUVmax) of primary colon cancer and serum neutrophil-to-lymphocyte ratio (NLR), and to assess the prognostic value of SUVmax and serum NLR in stage I and II colon cancer patients. METHODS: In this retrospective study a total of 128 patients with pathologically confirmed stage I and II colon cancer diagnosed between January 2014 and December 2017 were included. All patients underwent F-18 Fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and differential white blood cell (WBC) counts before surgery. The correlations between SUVmax and NLR were assessed. The prognostic value of SUVmax and NLR for predicting recurrence-free survival (RFS) was investigated. RESULTS: The mean NLR was 2.2 ± 1.2, and the mean SUVmax of primary tumor was 15.2 ± 7.9. There was significant correlation between NLR and SUVmax (rho=0.2, p=0.02). Mean follow-up period was 59.8 ± 19.2 months and 12 patients experienced a recurrence. In univariable analysis, NLR (p=0.0084, HR=5.0223, 95% CI=1.5117-16.6853), C-reactive protein (CRP) (p=0.021, HR=4.1115, 95% CI=1.2380-13.6551), carbohydrate antigen 19-9 (CA19-9) (p=0.0134, HR=4.2683, 95% CI=1.3519-13.4766), and Kirsten ras sarcoma viral oncogene (KRAS) mutation (p=0.0338, HR=3.4703, 95% CI=1.0998-10.9499) were significant prognostic factors for the recurrence. In multivariable analysis, NLR (p=0.0256, HR=4.1155, 95% CI=1.1887-14.2490) and CA19-9 (p=0.0257, HR=4.139, 95% CI=1.1880-14.4200) were independent prognostic factors for the recurrence. CONCLUSIONS: Significant correlation was observed between SUVmax of primary colon cancer and serum NLR. Furthermore, in the multivariable analysis conducted on early colon cancer cases, NLR and CA19-9 were found to be independently associated with RFS. This suggested that NLR could be used as a supplementary tool for identifying patients at high risk of recurrence in early colon cancer. However, SUVmax was not associated with prognosis, suggesting that it cannot be used for predicting prognosis in early colon cancer.

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.

The clinical challenge of relapsed diffuse large B-cell lymphoma with disseminated infection.

Fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is an essential tool in the diagnosis, staging, and assessment of treatment response in the management of lymphoma. Diffuse large B-cell lymphoma (DLBCL) represents the most common type of non-Hodgkin lymphoma (NHL). Although the curability rate is high, there are around 40% of patients exhibit relapse and present a therapeutic challenge. As important as 18F-FDG PET/CT is in the management of DLBCL, there are several limitations and potential pitfalls in assessing treatment response or relapse in patients who are also affected by active infectious disease concurrently. Hence, the knowledge of variable physiologic and altered physiologic uptake is of incredible essence when it comes to interpreting a complex scan. In this case report, we present a patient with relapsed DLBCL complicated by disseminated infection.

18F-FDG PET/CT imaging of several asymptomatic skeletal muscle metastases of mixed germ cell ovarian cancer.

Metastasis to muscles caused by ovarian cancer is very rare and has a poor prognosis. Performing a whole-body F18-FDG PET/CT scan makes it possible to examine the whole body in one study and detected lesions in unexpected places.

Lipid metabolism marker CD36 is associated with 18FDG-PET/CT false negative lymph nodes in head and neck squamous cell carcinoma.

Background: Lymph node metastasis frequently occurs in head and neck squamous cell carcinoma (HNSCC) patients, and [18F] fluorodeoxyglucose positron emission tomography with computed tomography (18FDG-PET/CT) examination for lymph node metastasis could result in false negativity and delay following treatment. However, the mechanism and resolution for 18FDG-PET/CT false negatives remain unclear. Our study was aim to found biomarkers for false negativity and true positivity from a metabolic perspective. Methods: Ninety-two patients diagnosed with HNSCC who underwent preoperative 18FDG-PET/CT and subsequent surgery in our institution were reviewed. Immunohistochemistry (IHC) examinations of glucose metabolism (GLUT1 and GLUT5), amino acid metabolism4 (GLS and SLC1A5), and lipid metabolism (CPT1A and CD36) markers were conducted on their primary lesion and lymph node sections. Results: We identified specific metabolic patterns of the false-negative group. Significantly, CD36 IHC score of primary lesions was higher in false-negative group than true-positive group. Moreover, we validated pro-invasive biological effects of CD36 by bioinformatics analysis as well as experiments. Conclusion: IHC examination of CD36 expression, which is a lipid metabolism marker, in primary lesions could distinguish HNSCC patients' lymph nodes false negatives in 18FDG-PET/CT.

Impact of routine preoperative 18 FDG PET/CT on the surgical management of primary colorectal cancer.

OBJECTIVES: Determine the usefulness of [18F]-fluorodeoxyglucose positron emission tomography/computed tomography (18 FDG-PET/CT) in the preoperative setting of colorectal cancer (CRC), assessing its impact on changes in management strategy. METHODS: Retrospective study of CRC patients who underwent preoperative 18 FDG-PET/CT and CT staging scans in a single referral center. The agreement between 18 FDG-PET/CT, contrast-enhanced CT, and colonoscopy for the surgical location was compared using the κ coefficient. Maximum standardized uptake (SUVmax ) value was obtained. Univariate and multivariate analyses were conducted. RESULTS: One hundred ninety-five patients were included. 18 FDG-PET/CT improved tumor localization in 84.6% (165/195) of cases (κ value 0.798, p < 0.001), thus correcting endoscopic errors 69.7% (30/43) of the time. In patients with incomplete colonoscopies, 18 FDG-PET/CT detected synchronous tumors in 2.5% (5/195) patients, overlooked by CT staging scans. Based on extracolonic 18 FDG-uptake, the second primary malignancy was diagnosed in 7(3.6%,7/195) patients and total accuracy for lymph node and distant metastasis was 66.1% and 98.4%, respectively. The treatment plan was altered in 30 (15.4%, 30/196) patients. There was a significant association between the SUVmax and tumor size (odds ratio [OR] 4.254, p = 0.003) and the depth of tumor invasion (OR 1.696, p = 0.026). CONCLUSIONS: Based on its ability to aid in preoperative evaluation and definitively alter surgical treatment planning, 18 FDG-PET/CT should be further evaluated in primary CRC.