A different perspective on 18F-FDG PET radiomics in colorectal cancer patients: The relationship between intra & peritumoral analysis and pathological findings.

OBJECTIVE: We aimed to determine the value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) based primary tumoral and peritumoral radiomics in the prediction of tumor deposits (TDs), tumor budding (TB) and extramural venous invasion (EMVI) of colorectal cancer (CRC). METHODS: Our retrospective study included 77 CRC patients who had preoperative 18F-FDG PET/CT between June 2020 and February 2022. A total of 131 radiomic features were extracted from primary tumors and peritumoral areas on PET/CT fusion images. The relationship between TDs, TB, EMVI and T stage in the postoperative pathology of the tumors and radiomic features was investigated. Features with a correlation coefficient (CC) less than 0.8 were analyzed by logistic regression. The area under curve (AUC) obtained from the receiver operating characteristic analysis was used to measure the model performance. RESULTS: A model was developed from primary tumoral and peritumoral radiomics data to predict T stage (AUC 0.931), and also a predictive model was constructed from primary tumor derived radiomics to predict EMVI (AUC 0.739). Radiomic data derived from the primary tumor was obtained as a predictive prognostic factor in predicting TDs and a peritumoral feature was found to be a prognostic factor in predicting TB. CONCLUSIONS: Intratumoral and peritumoral radiomics derived from 18F-FDG PET/CT are useful for non-invasive early prediction of pathological features that have important implications in the management of CRC.

Primary Isolated Breast Lymphoma Presenting as Primary Breast Cancer with 18F-FDG PET/CT.

A 40-year-old woman with a palpable mass lesion in her right breast suggested as breast cancer was admitted to 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) unit for the metabolic characterization of the lesion and for the staging of the disease. The patient had no fever and no evidence of weight loss or night sweats. 18F-FDG PET/CT revealed an isolated solid mass lesion with increased 18F-FDG uptake in the upper outer quadrant of the right breast and increased 18F-FDG uptake in the lymph nodes of the right axilla suspected as primary breast cancer and its local lymph node metastasis. There was no other pathological 18F-FDG uptake in the whole body. Excisional biopsy histopathology revealed diffuse large B-cell non-Hodgkin lymphoma.

The Evaluation of Preoperative 18F-FDG PET/CT in Patients with Endometrial Cancer and the Correlation Between PET Parameters and Postoperative Pathology Results.

OBJECTIVES: Endometrial cancer (EC) is the most common gynecological malignancy. The 18fluorine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is used for initial staging, evaluating treatment response, and detecting recurrence. This study aimed to investigate the diagnostic value of preoperative PET/CT in EC staging and determine the volumetric PET parameters that are accurate predictors of histopathological tumor characteristics. METHODS: Preoperative PET/CT data of 66 patients with EC were retrospectively analyzed. Patients were divided into low and high-risk groups according to the European Society for Medical Oncology criteria. The maximum standardized uptake value (SUVmax), SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the primary lesion and pathological lymph nodes were noted. The International Federation of Gynecology and Obstetrics (FIGO) classifications, histopathology, the depth of myometrial invasion (MI), lymph node metastasis (LNM), cervical stromal invasion (CSI), and tumor sizes were noted. RESULTS: The SUVmax, TLG, and MTV values of high and low-risk groups were significantly different. TLG was the most useful parameter in differentiating risk groups. PET/CT had 90% sensitivity, 96.3% specificity, 81.8% positive predictive value, 98.1% negative predictive value, and 95.45% accuracy in assessing LNM. MTV and TLG values in patients with non-endometrioid pathology were higher than those with endometrioid. The SUVmax, MTV, and TLG of patients with deep MI were higher than those with superficial MI. TLG values of patients with CSI were higher than those without CSI. Patients with LNM had higher MTV and TLG values than those without LNM. A significant difference was found in TLG, MTV, and SUVmax values between patients with FIGO stage I-II and patients with FIGO stage III and above. CONCLUSION: SUV and volumetric parameters obtained from PET/CT, especially TLG, are strong predictors of tumor characteristics, such as MI and CSI, FIGO stages, and LNM, and are useful in noninvasively defining the risk groups in the preoperative period.

Prediction of early biochemical response after 177Lu-PSMA radioligand therapy with 68Ga-PSMA PET, a different perspective with quantitative parameters.

OBJECTIVE: In this study, our aim was to evaluate the relationship of the quantitative data obtained from pretreatment 68Ga prostate-specific membrane antigen (PSMA) PET-computerized tomography (PET/CT) with treatment response of the patients with the diagnosis of metastatic castrationresistant prostate cancer (mCRPC) who received 177Lu-PSMA radioligand therapy (RLT). METHODS: The patients who were given three or four cycles of 177Lu-PSMA RLT between January 2016 and June 2018 were evaluated retrospectively. Volumetric data; PSMA tumor volume (TV) and total lesion (TL) PSMA, were obtained from 68Ga-PSMA PET/CT for whole (PSMA-TVT and TL-PSMAT). The distance between the two furthest lesions (Dmax) was calculated. Posttreatment early prostate-specific antigen (PSA) values on the fourteenth day after treatment were obtained. According to the PSA responses, the patients were divided into two groups as progressed and nonprogressed. In univariate analysis, the relationship of PET quantitative data with biochemical response groups was evaluated with Mann-Whitney U test. Logistic regression was used in multivariate analysis. RESULTS: A total of 38 patients were included in the study. In univariate analysis, Dmax, PSMA-TVT and TL-PSMAT values were obtained at lower levels in the progressed group. In multivariate analysis, only Dmax was found to be a prognostic factor in predicting early biochemical response. CONCLUSION: Dmax is the most prognostic parameter in predicting the early biochemical response in patients with mCRPC; high total tumor volume and burden are also parameters that give us an idea about the response to treatment. The success rate will be higher if 177Lu-PSMA RLT treatment is planned for patients with higher tumor volume and spread.

Dual time point imaging of staging PSMA PET/CT quantification; spread and radiomic analyses.

OBJECTIVE: The aims were to evaluate the performance of models that predict Gleason Grade (GG) groups with radiomic data obtained from the prostate gland in dual time 68Ga-Prostate Specific Membrane Antigen (PSMA) Positron Emission Tomography/Computerized Tomography (PET/CT) images for prostate cancer (PCa) staging, and to analyze the contribution of late imaging to the radiomic model and to evaluate the relationship of the distance between tumor foci in the body (Dmax) obtained in early PET images with histopathology and prostate specific antigen (PSA) value. METHODS: Between October 2020 and August 2021, 41 patients who underwent 68Ga-PSMA PET/CT for staging of PCa were retrospectively analyzed. Volumetric and radiomics data were obtained from early and late PSMA PET images. The differences between age, metastasis status, PSA, standard uptake value (SUV), volumetric and radiomics parameters between GG groups were analyzed. Early and late PET radiomic models were created, area under curve (AUC), sensitivity, specificity and accuracy values of the models were obtained. In addition, the correlation of Dmax values with total PSMA-tumor volume (TV), Total lesion (TL)-PSMA and PSA values was evaluated. In metastatic patients, the difference in Dmax between GG groups was analyzed. RESULTS: There was a significant difference between patients with GG ≤ 3 and > 3 in 35 of the early PET radiomic features. In the early PET model, multivariate analyses showed that GLRLM_RLNU and PSA were the most meaningful parameters. The AUC, sensitivity, specificity and accuracy values of the early model in detecting patients with GG > 3 were calculated as 0.902, 76.2%, 84% and 78.1%, respectively. In 36 late PET radiomic features, there was a significant difference between patients with GG ≤ 3 and > 3. In multivariate analyses; SHAPE_compacity and PSA were obtained as the most meaningful parameters. The AUC, sensitivity, specificity and accuracy values of the late model in detecting patients with GG > 3 were calculated as 0.924, 85.7%, 85% and 85.4%. There was a strong correlation between Dmax and PSA values (p < 0.001, rho: 0.793). Dmax showed strong correlation with PSMA-TVtotal and TL-PSMAtotal (p < 0.001, rho: 0.797; p < 0.001, rho: 0.763, respectively). In patients with metastasis, median Dmax values of the GG > 3 group were higher than GG ≤ 3 group; A statistically significant difference was obtained between these two groups (p = 0.023). CONCLUSIONS: Model generated from the late PSMA PET radiomic data had better performance in the current study. Without the use of invasive methods, the heterogeneity and aggressiveness of the primary tumor and the prediction of GG groups may be possible with 68Ga-PSMA PET/CT images obtained for diagnostic purposes especially with late PSMA PET/CT imaging.

A case of soft tissue hematoma detected incidentally on 99m TC-labelled RBC gastrointestinal bleeding SPECT/CT.

We report an incidental finding on 99mTc-labelled RBC gastrointestinal bleeding scintigraphy of a 49-year-old female patient referred to our clinic in order to localize the bleeding site. The patient has also been suffering from chronic renal insufficiency and received several interventions of femoral catheterization. During the follow-up, an intense uptake was observed at the right inguinofemoral area which is evaluated as a large soft tissue hematoma and confirmed by SPECT/CT subsequently. On the 24th h delayed image an activity accumulation along the bowel trace on the right side of the abdomen was seen as evidence of lower gastrointestinal bleeding.

Usefulness of 18F-FDG PET/CT in Cutaneous Melanoma Patients with Negative Sentinel Lymph Nodes and High Clark Levels.

OBJECTIVE: We investigated the utility of PET/CT in cutaneous melanoma (CM) patients with pathological negative sentinel lymph nodes (SLN), within the first year. METHODS: The results of PET/CTs and SLN biopsy (SLNB) in 65 patients (39 male and 26 female, mean age 53.8) with a PET/CT in the first postoperative year were evaluated. Within this cohort, the utility of early PET/CT imaging was assessed in patients with negative SLNB. McNemar test was used to compare PET/CT findings with SLNB results. RESULTS: Out of 43 patients with pathologically positive SLNs, 23 patients (53.5%) had positive and 20 patients (46.5%) had negative findings on PET/CT within the first postoperative year. On the other hand, PET/CT results of 22 patients with negative SLNBs were found to be negative in 19 patients (86.4%) and positive in 3 patients (13.6%). For the patients with negative SLNB results, the detection rate of distant metastasis with PET/CT was significantly lower (p<0.001) than that in patients with positive SLNBs. CONCLUSION: Our results showed that 18F-FDG PET/CT will most likely (86.4%) be negative during the first postoperative year in patients with a negative SLNB. Therefore, it is concluded that this modality would not provide any significant clinical contribution within this time frame.