Sadık Server’s research while affiliated with Group Florence Nightingale Hastaneleri and other places

Background Whole-body positron emission tomography/magnetic resonance imaging (WB-PET/MRI) is increasingly used in the initial evaluation of oncology patients. The purpose of this study was to compare the diagnostic performance of WB MRI sequences, attenuation-corrected raw data positron-emission tomography (AC PET), and PET/MRI fused images to detect bone metastases. Patients and methods We included 765 consecutive oncologic patients who received WB-PET/MRI from between January 2017 and September 2023. The presence of bone metastases was assessed using the individual sequences by two radiologists. Interobserver agreement was calculated. A receiver operating characteristic (ROC) analysis was performed to assess the performance of each individual sequence and fused images. Results Interobserver agreement for the detection of bone metastases on all sequences ranged from good to very good. The reading of the combination of MRI sequences with PET images showed statistically significantly better performance than the reading of individual MRI sequences and PET component only. Contrast enhanced T1 W Volume-interpolated breath-hold examination (CE T1W VIBE) sequence superior to PET for the detection of bone metastasis, but the statistical significance was not as high as with T1W-PET and CE T1W-PET fused images. The highest performance was achieved by the fused CE T1W-PET images with sensitivity of 100%, specificity of 92%, PPV of 96%, and NPV of 100%. Conclusions The combination of these CE T1W VIBE sequences with PET images have the highest diagnostic performance in detecting bone metastases in oncologic patients. This sequence should be integrated in WB-PET/MRI acquisitions for initial staging of cancer.

Objective: The aim of our study is to investigate probable differences between the incidence of target sign detected by diffusion-weighted magnetic resonance imaging (DWI) and apparent diffusion coefficient (ADC) values between metastases and hepatocellular carcinomas (HCC). Materials and Methods: A total of 155 lesions obtained from 57 (female/male: 18/39) patients were included in the study. Dimensions of lesions, the appearance of lesions detected by DWI, minimum ADC (ADCmin) values, and average ADC (ADCav) values were evaluated with 1.5 Tesla MRI using b= 0 and b = 1000 s/mm2 values. Differences between metastases and HCC were investigated in terms of defined parameters. Also, ROC (receiver operating curve) analysis was used to evaluate the performance of ADCmin and ADCav parameters in distinguishing metastases from HCC. Results: Of the lesions, 131 were metastases, while 24 were HCC. The image showing centrally hypointense, periphery hyperintense signal in DWI defined as target sign. Target sign detected in 72 metastatic lesions (55%) and 6 HCC lesions (25%) with DWI, and the rate of target sign detection was higher in the metastatic group compared with HCC (p

Purpose: The aim of our study was to determine which imaging method was superior in detecting brain metastases by comparing contrast-enhanced MRI and 18F FDG PET / MRI which were obtained simultaneously. Methods: From August 2015 to December 2018, 480 consecutive patients with histopathologic proven primary malignancy (188 men and 292 women; mean age+ standard deviation, 45 years+ 25,4) were retrospectively evaluated. All patients underwent 18F-FDG PET/MRI during follow-up of their malignancies. Results: Brain metastases (BM) were found in 33 (25 Female and 8 Male) of 480 patients. Contrast-enhanced MRI revealed 190 brain metastases (BM) in 33 patients (100%), while 18F-FDG PET data was accurately identified 50 (26.3%) BM lesions in 16 (48.5%) patients. Based on measurements on contrast-enhanced MR images, the maximum BM lesion size was 40.1mm (mean: 6.64mm±6.39mm, range: 0.9mm-40.1mm). Mean lesion size ± SD was 12.88±8.13mm in 18F-FDG PET/MRI detectable lesions. Conclusion: Contrast-enhanced brain MR is more likely to detect brain metastases than 18F-FDG PET / MRI, and is still the gold standard imaging method for the detection of brain metastases.

Purpose: To evaluate the Intravoxel Incoherent Motion (IVIM) parameter alterations of liver metastases of colorectal carcinoma (CRC) during antiangiogenic bevacizumab combination therapy. Methods: Twenty-five CRC liver metastases who were all treated with bevacizumab in combination with FOLFOX-or-FOLFIRI protocols were enrolled in the study. MRI was performed in a 1.5T scanner pre-treatment (PT) and at the 3rd, 6th, and 9th months of the therapy. Routine abdominal MRI sequences and an IVIM-DWI (diffusion weighted imaging) sequence were obtained. IVIM-DWI sequence was executed with 16 b-values varying from 0-to-1400s/mm2. The mean values of apparent diffusion coefficient (ADC), true diffusion (D), pseudo-diffusion (D*), and perfusion fraction (f) of each metastases were obtained for all b-values and the time related changes were recorded to analyze the chronologic responses to antiangiogenic therapy. The RECIST1.1 criteria were used for the evaluation of treatment response. Results: The diameters of the metastases diminished significantly at 9th month when compared with PT (p=0.03). D (p= 0.10) and ADC (p= 0.21) values of the metastases increased at the 9th month of therapy. D* was the highest at 3rd month (p=0.24), and a decreased at 6th (p= 0.97) and 9th months (p= 0.87) of therapy. The f had the highest peak at 3rd month (p=0.51), and started to decrease after 3rd month. At the 6th month f decreased to lowest values (p=0.12). Conclusion: IVIM parameters, particularly the perfusion fraction may quantitatively reflect the response of antiangiogenic treatment. The antiangiogenic response manifests after the 3rd month of the therapy before the RECIST related response.

Objective: To evaluate the diagnostic accuracy of Intravoxel Incoherent Motion (IVIM) parameters for assessment of tumor response after locoregional treatment (LRT) of hepatocellular carcinoma (HCC). Methods: Fifteen patients with HCC who had undergone LRTs (11 transarterial radioembolization, 4 transarterial chemoembolization) were included. In addition to routine upper abdominal magnetic resonance imaging sequences, IVIM with 16 different b values and conventional diffusion weighted imaging with 3 different b factors were obtained immediately before and 8 weeks after LRTs. Magnetic resonance imaging response was evaluated according to modified Response Evaluation Criteria in Solid Tumors (mRECIST) and HCCs were categorized into 2 subgroups, responders and nonresponders. Quantitatively, the number of diffusion-changes were calculated with apparent diffusion coefficient (ADC) and IVIM parameters, including mean D (true diffusion coefficient), pseudo-diffusion coefficient associated with blood flow, and f (perfusion fraction) values. Subsequently, the pre- and post-treatment parameters were compared using the Mann-Whitney U test. Results: Considering all HCCs, a significant decrease was observed according to mRECIST criteria (-38.43 ± 16.49). The ADC and D values after LRTs were significantly higher than those of the preceding ones. The f values after LRTs were significantly lower than those of pre-treatment. In the responders group, ADC and D values were significantly increased and f values were significantly decreased after LRTs. No difference of statistical significance was achieved in the nonresponders group. Conclusions: ADC values and IVIM parameters appear to reflect the response of LRTs as effectively as those of mRECIST. This promises new horizons in the management of pretransplant patients, especially in renal insufficiency clinical settings, owing to the elimination of contrast media administration.

Background: The purpose of this study was to determine the utility of some imaging findings in predicting microvascular invasion (MVI) and hepatocellular carcinoma (HCC) recurrence risk after liver transplantation. Method: This retrospective study included 123 patients with histopathologically proven HCC at explant. All HCCs were classified as MVI positive (group I) or negative (group II) based on histopathological findings. In each group, multifocality, largest tumor size, bulging (tumor causing liver capsule expansion), beak sign (the acute angle between the tumor and liver parenchyma), and diffusion restriction on diffusion weighted images (DWI) were evaluated. These findings were compared between the groups by Student's t test. The relation between the parameters and MVI was analyzed by using the Spearman's correlation test. Results: Of the total patients, 30.1% had MVI (group I) and 69.9% (group II) did not have MVI. Presence of beak sign (P ≤ .005), bulging sign (P = .002), and diffusion restriction (P = .045) were significantly more frequent in group I than group II. The beak sign, bulging sign, and diffusion restriction were correlated with presence of MVI. Largest tumor size and multifocality were higher in group I than group II, but the differences were not statistically significant. Conclusion: Radiologists and transplant surgeons should be aware of some clue imaging findings, especially beak and bulging signs because these findings may predict the presence of MVI in HCC. These patients might benefit from histologic confirmation of the tumor characteristics through biopsy and subsequent bridging treatment options before liver transplantation to reduce the risk of recurrence.

Background: In living-donor liver transplantation, donor hepatic steatosis is crucial for both the donor and the recipient. Body mass index (BMI) and the unenhanced computed tomography liver attenuation index (CT LAI) are noninvasive methods to predict hepatic steatosis in living-donor liver candidates. Aim: To analyze the diagnostic accuracy of CT LAI in conjunction with different BMI values for macrovesicular steatosis in living-donor liver candidates. Methods: A total of 264 potential liver donors were included. The diagnostic accuracy of 2 CT LAI cut-offs and 3 BMI cut-off values for the assessment of hepatic steatosis ≥15% and ≤5% was determined. Results: Using CT LAI, the area under the receiver operating characteristic curve was 0.97 (95% CI = 0.89-0.99) for hepatic steatosis ≥15% in donors with BMI <25 kg/m2. For detecting hepatic steatosis ≥15%, a CT LAI ≤0 had specificities of 100%, 76.2%, and 55.6% and positive predictive values of 100%, 95.5%, and 93.5% for patients with BMI values <25 kg/m2, 25 to 29.9 kg/m2, and ≥30 kg/m2, respectively. According to logistic regression analyses, only CT LAI ≤0 was found to be independently associated with hepatic steatosis ≥15%. Conclusions: In donors with BMI <30 kg/m2 and a CT LAI value >6, liver biopsy might be avoided. Biopsy may be reserved solely for donors with CT LAI value >0 and BMI ≥30 kg/m2 as the diagnostic accuracy of computed tomography for predicting hepatic steatosis decreases with increasing BMI.