Ozgur Kilickesmez

Diffusion-weighted imaging of the renal and adrenal lesions.

Objectives: The purpose of this study was to calculate the apparent diffusion coefficient (ADC) values of different renal and adrenal lesions to evaluate the ability of diffusion-weighted imaging in characterizing masses and determining malignancy. Methods: A total of 52 patients consisting of 67 renal lesions and 28 patients with 33 adrenal lesions in addition to 50 healthy controls with normal kidneys were enrolled in the study. Diffusion-weighted imaging was performed with b factors of 0, 500, and 1000 s/mm2, and the ADCs of the normal kidney and renal and adrenal lesions were calculated. Results: The mean (SD) ADCs of the renal cortex and medulla of the control group were 2.08 (0.22) × 10−3 and 1.94 (0.18) × 10−3 mm2/s, respectively. Focal renal lesions were as follows: simple cysts (2.94 [0.20] × 10−3 mm2/s), hemorrhagic cysts (1.71 [0.38] × 10−3 mm2/s), angiomyolipomas (1.40 [0.21] × 10−3 mm2/s), renal cell carcinomas (1.06 [0.39] × 10−3 mm2/s), metastases (1.50 [0.13] × 10−3 mm2/s), and hydronephrosis (1.54 [0.25] × 10−3 mm2/s). The mean ADCs of all these pathologies were significantly different when compared with normal parenchyma. Diffusion-weighted imaging was also able to differentiate angiomyolipomas and hemorrhagic cysts from renal cell carcinomas. Adrenal lesions were subgrouped as adenomas (1.41 [0.27] × M10−3 mm2/s), nonadenomatous solid masses (1.08 [0.28] × 10−3 mm2/s), and cysts (2.82 [0.24] × 10−3 mm2/s). The mean ADCs of adenomas were significantly different when compared with nonadenomatous solid masses and cysts. Conclusions: Our findings show that ADC measurement has a potential ability to differentiate benign and malignant focal renal and adrenal lesions with the guidance of conventional sequences. When used alone, diffusion-weighted imaging may lead to misdiagnoses due to overlapping ADCs of the lesions.

Quantitative Diffusion-Weighted Magnetic Resonance Imaging of Normal and Diseased Uterine Zones

Background: Magnetic resonance (MR) imaging has been established as the best imaging modality for the detection, localization, and staging of uterine cancers. Recently, the usefulness of diffusion-weighted imaging (DWI) in the diagnosis of cancers has been reported in several studies. Purpose: To calculate the apparent diffusion coefficient (ADC) values of normal uterine zones as well as benign and malignant uterine diseases, and to determine a cut-off ADC value for the quantitative detection of uterine malignancies with DWI. Material and Methods: Eighty-seven patients (mean age 53 years) with 107 benign and malignant uterine pathologies and 50 healthy controls (mean age 38 years) were enrolled in the study. DWI was performed with b factors of 0, 500, and 1000 s/mm2. Results: The ADC values of benign and malignant lesions were compared using Students t test. The mean and the standard deviation of the ADC values of the control group were as follows: myometrium 1.76±0.19×10−3 mm2/s, junctional zone 0.99±0.18×10−3 mm2/s, endometrium 1.65±0.33×10−3 mm2/s, and cervix 1.71±0.17×10−3 mm2/s. There was a statistically significant difference among the ADC values of normal myometrium and leiomyomas (1.47±0.36×10−3 mm2/s; P<0.009), endometrium and endometrial carcinomas (0.86±0.13×10−3 mm2/s; P<0.001), myometrium-junctional zone and adenomyosis (1.24±0.20×10−3mm2/s; P<0.001), and cervix and cervical carcinomas (0.91±0.14×10−3 mm2/s; P<0.001). The ADC values differed significantly between malignant (0.88±0.11) and benign lesions (1.55±0.33; P<0.01). A cut-off value for malignant lesions of 1.05×10−3 mm2/s yielded a sensitivity, specificity, and accuracy of 95.83%, 94.55%, and 94.94%, respectively. Conclusion: The present study shows that ADC measurements have the potential to quantitatively differentiate between normal and cancerous tissues of the uterine zones. We propose adding DWI as an adjunct sequence in the MR protocol for the assessment of uterine lesions.

Diffusion-weighted imaging of the rectosigmoid colon: preliminary findings.

Objectives: The aims of this study were to determine and evaluate the apparent diffusion coefficient (ADC) values of the rectal wall for identifying inflammatory bowel disease (IBD) and rectosigmoid (rectum and sigmoid colon) malignancies. Methods: Diffusion-weighted magnetic resonance imaging (DWI) findings of 23 patients (mean age, 57 years) consisting of 14 patients with rectosigmoid adenocarcinomas and 9 patients with IBD (6 with ulcerative colitis and 3 with Crohn disease) were retrospectively reviewed. In addition, 30 healthy controls (mean age, 45 years) were enrolled in the study. Diffusion-weighted imaging was performed with b factors of 0, 500, and 1000 s/mm2. Results: The mean (SD) ADC values of the control, IBD, and rectosigmoid adenocarcinoma groups were 1.47 (0.19) × 10−3 mm2/s, 1.37 (0.12) × 10−3 mm2/s, and 0.97 (0.14) × 10−3 mm2/s, respectively. Among the patients with IBD, 2 were in the active, and the rest were in the inactive period, with mean (SD) ADC values of 1.21 (0.08) × 10−3 and 1.42 (0.09) × 10−3, respectively. The ADC values of the normal rectum and rectosigmoid malignancy group and rectosigmoid carcinoma and IBD groups were significantly different (P < 0.01). A cutoff value for carcinomas of 1.14 × 10−3 mm2/s yielded a sensitivity and specificity of 93.3% and 93.3%, respectively. Conclusions: Our preliminary findings show that quantitative DWI may be able to differentiate the normal rectum from neoplastic involvement, in addition to distinguishing between inflammatory and neoplastic involvements. However, radiologists should be aware of possible overlaps that may lead to misdiagnoses when DWI is used alone.

Value of apparent diffusion coefficient measurement for discrimination of focal benign and malignant hepatic masses

The purpose of our study was to investigate the value of diffusion‐weighted magnetic resonance imaging (DW‐MRI) to discriminate benign and malignant focal lesions of the liver using parallel imaging technique. A total of 77 patients and 65 healthy controls were enrolled in the study. DW‐MRI was performed with b‐factors of 0, 500 and 1000 s/mm2, and the apparent diffusion coefficients (ADC) values of the normal liver and the lesions were calculated. The mean ADC value of the focal liver lesions were as follows: simple cysts (3.16 ± 0.18 × 10−3 mm2/s), hydatid cysts (2.58 ± 0.53 × 10−3 mm2/s), hemangiomas (1.97 ± 0.49 × 10−3 mm2/s), metastases (1.14 ± 0.41 × 10−3 mm2/s) and hepatocellular carcinomas (HCC) (1.15 ± 0.36 × 10−3 mm2/s). The mean ADC values of all the disease groups were statistically significant when compared with the mean ADC value of the normal liver (1.56 ± 0.14 × 10−3 mm2/s), (P < 0.01). There were also statistically significant differences among the ADC values of hemangiomas and HCC metastases (P < 0.01), and simple and hydatid cysts (P < 0.008). However, there was no statistically significant difference between HCC and metastases. The present study showed that ADC measurement has the potential to differentiate benign and malignant focal hepatic lesions. We propose to add DW sequence in the MR protocol for the detection and quantitative discrimination of hepatic pathologies.

The utility of high b-value DWI in evaluation of ischemic stroke at 3 T

PURPOSE The utility of DWI with high b-value in ischemic stroke is still unsettled. The purpose of this study is to compare high b-value (3000) and standard b-value (1000) diffusion-weighted images in patients with ischemic stroke at 3T. MATERIALS AND METHODS 27 patients with acute stroke who were admitted to the hospital during the first 24h after symptom onset were included in this study. All patients had a brain MRI study with stroke protocol including standard (b=1000) DWI and high b-value (b=3000) DWI sequences at 3T MR scanner. Number and localization of the lesions were assessed MR signal intensities (SI), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), contrast ratio (CR) and apparent diffusion coefficient (ADC) values of the lesions and normal parenchyma on DWI with b=1000 and b=3000 sequences were measured. RESULTS All patients with acute stroke revealed hyperintense lesions due to restricted diffusion on DWI with both b-values. However, lesions of restricted diffusion were more conspicuous in b=3000 value DWI than b=1000, and additional 4 ischemic lesions were detected on b=3000 DWI. SNR, CNR, SI and also ADC values in both stroke area and normal parenchyma were lower at b=3000 than the value at b=1000. At b=3000, CR was significantly greater than b=1000 images. CONCLUSIONS Although quantitative analysis shows higher SI, SNR and CNR values with standard b-value (b=1000) diffusion-weighted imaging, using higher b-value may still be beneficial in detecting additional subtle lesions in patients whose clinical findings are not correlated with standard b-value DWI in stroke.

T2-weighted MRI of the upper abdomen: comparison of four fat-suppressed T2-weighted sequences including PROPELLER (BLADE) technique.

RATIONALE AND OBJECTIVES The aim of this study was to compare four different fat-suppressed T2-weighted sequences with different techniques with regard to image quality and lesion detection in upper abdominal magnetic resonance imaging (MRI) scans. MATERIALS AND METHODS Thirty-two consecutive patients referred for upper abdominal MRI for the evaluation of various suspected pathologies were included in this study. Different T2-weighted sequences (free-breathing navigator-triggered turbo spin-echo [TSE], free-breathing navigator-triggered TSE with restore pulse (RP), breath-hold TSE with RP, and free-breathing navigator-triggered TSE with RP using the periodically rotated overlapping parallel lines with enhanced reconstruction technique [using BLADE, a Siemens implementation of this technique]) were used on all patients. All images were assessed independently by two radiologists. Assessments of motion artifacts; the edge sharpness of the liver, pancreas, and intrahepatic vessels; depictions of the intrahepatic vessels; and overall image quality were performed qualitatively. Quantitative analysis was performed by calculation of the signal-to-noise ratios for liver tissue and gallbladder as well as contrast-to-noise ratios of liver to spleen. RESULTS Liver and gallbladder signal-to-noise ratios as well as liver to spleen contrast-to-noise ratios were significantly higher (P < .05) for the BLADE technique compared to all other sequences. In qualitative analysis, the severity of motion artifacts was significantly lower with T2-weighted free-breathing navigator-triggered BLADE sequences compared to other sequences (P < .01). The edge sharpness of the liver, pancreas, and intrahepatic vessels; depictions of the intrahepatic vessels; and overall image quality were significantly better with the BLADE sequence (P < .05). CONCLUSION The T2-weighted free-breathing navigator-triggered TSE sequence with the BLADE technique is a promising approach for reducing motion artifacts and improving image quality in upper abdominal MRI scans.

Diffusion tensor imaging of the kidney at 3 Tesla: normative values and repeatability of measurements in healthy volunteers

PURPOSE To evaluate the feasibility of renal diffusion tensor imaging and determine the normative fractional anisotropy and apparent diffusion coefficient values at 3 Tesla magnetic resonance imaging (MRI) using parallel imaging and free breathing technique. MATERIALS AND METHODS A total of 52 young healthy volunteers with no history of renal disease were included in the study. MRI examinations were performed with 3 Tesla MRI equipment, using six-channel phased array SENSE Torso coil. In all subjects, T2-weighted turbo spin echo and diffusion tensor imaging using single shot echo planar imaging sequences were obtained in the coronal plane with free breathing. Field of view, slice thickness, and slice gap values were identical for both sequences for anatomic correlation during analysis of diffusion tensor imaging data. Parallel imaging method was used with a SENSE factor of 2. Diffusion tensor parameters of the cortex and medulla were determined and the intra- and inter-observer measurement variances were calculated. RESULTS The mean fractional anisotropy of the medulla was significantly higher than that of the cortex, whereas the mean apparent diffusion coefficient of the medulla was lower when compared with that of the cortex. According to the two-sided paired samples Students t test, the intra- and inter-observer measurements correlated well. CONCLUSION This study shows the feasibility of renal diffusion tensor imaging and repeatibility of diffusion tensor parameter measurements in 3 Tesla MRI.

Diffusion-weighted imaging of adnexal torsion

We report the diffusion-weighted imaging findings (DWI) of a case with ovarian torsion. Magnetic resonance imaging revealed a large cyst within a non-enhancing ovary. DWI depicted restricted diffusion which in turn was found to be related with the infarction of the ovary in the laparoscopic salpingo-oophorectomy performed.

Is quantitative diffusion-weighted MRI a reliable method in the assessment of the inflammatory activity in ulcerative colitis?

PURPOSE We investigated the relationship between the apparent diffusion coefficient (ADC) values of the colonic wall and the pathologic pericolonic lymph nodes (PCLNs) and inflammatory activity in ulcerative colitis patients by diffusion-weighted magnetic resonance imaging (DW-MRI). MATERIALS AND METHODS A total of 28 ulcerative colitis patients (9 endoscopically active, 10 subacute and 9 in remission) were evaluated by DW-MRI with 0, 500 and 1000 s/mm² b-values. The ADC values of the rectum and sigmoid colon walls and the adjacent PCLNs were obtained for quantitative analysis. The DW-MRI findings were compared to the disease activity. RESULTS The ADC values of the sigmoid colon were similar in patients with active, subacute and remissive ulcerative colitis (P = 0.472). The ADC values of the rectum were different (P = 0.009) between patients in the active (1.08 ± 0.14×10⁻³ mm²/s) and subacute phases (1.13 ± 0.23×10⁻³ mm²/s) of disease and those in remission (1.29 ± 0.17×10⁻³ mm²/s). The ADC values of the PCLNs (P = 0.899) did not differ with respect to disease activity. CONCLUSION DW-MRI is useful in identifying disease activity in ulcerative colitis patients, especially with respect to the rectum. The ADC values of the rectum increase during remission and decrease in patients with active distal colitis. The ADC values of the PCLNs were not useful in determining disease activity.

Utility of diffusion-weighted MRI for assessing liver fibrosis in patients with chronic active hepatitis.

PURPOSE We evaluated the utility of quantitative diffusion-weighted magnetic resonance imaging (DW-MRI) for assessing both the relationship between the degree of fibrosis and the histological activity index (HAI) in chronic hepatitis (CH) cases and attempted to determine whether the apparent diffusion coefficient value (ADC) could be used as a reference for the degree of fibrosis detected by histology. MATERIALS AND METHODS The study population consisted of 55 CH patients (Group I) and a control group of 30 volunteers (Group II). Group I consisted of 31 CH-B (CHB), 18 CH-C (CHC) and 6 non-alcoholic steatohepatitis patients. DW-MRI of the liver with b values of 0, 500 and 1000 s/mm(2) was performed, and liver biopsies of the patients were obtained two weeks later. The ADC value, degree of liver fibrosis and HAI were compared within Group I, and the ADC values of both groups were compared with each other. RESULTS The ADC was lower in Group I than in Group II (P < 0.05). The ADC of the left lobe lateral (LL) (P < 0.05), left lobe medial (LM) and right lobe anterior (RA) segments (P < 0.01) in Group I were lower than those of Group II. There was no relationship between HAI and the ADC of LL, LM, RA and right lobe posterior (RP) segments in Group I. Additionally, there was no correlation between fibrosis scores and ADC in Group I, whereas there was a negative correlation between fibrosis scores and ADC values of the LL (28.3%) and RP (29.5%). CONCLUSION CH patients had lower ADC values. There was no correlation between ADC values and fibrosis stages or ADC and HAI values. Quantitative DW-MRI was not useful in determining the degree of fibrosis in liver tissue.PURPOSE: We evaluated the utility of quantitative diffusion-weighted magnetic resonance imaging (DW-MRI) for assessing both the relationship between the degree of fibrosis and the histological activity index (HAI) in chronic hepatitis (CH) cases and attempted to determine whether the apparent diffusion coefficient value (ADC) could be used as a reference for the degree of fibrosis detected by histology. MATERIALS AND METHODS: The study population consisted of 55 CH patients (Group I) and a control group of 30 volunteers (Group II). Group I consisted of 31 CH-B (CHB), 18 CH-C (CHC) and 6 non-alcoholic steatohepatitis patients. DW-MRI of the liver with b values of 0, 500 and 1000 s/mm(2) was performed, and liver biopsies of the patients were obtained two weeks later. The ADC value, degree of liver fibrosis and HAI were compared within Group I, and the ADC values of both groups were compared with each other. RESULTS: The ADC was lower in Group I than in Group II (P < 0.05). The ADC of the left lobe lateral (LL) (P < 0.05), left lobe medial (LM) and right lobe anterior (RA) segments (P < 0.01) in Group I were lower than those of Group II. There was no relationship between HAI and the ADC of LL, LM, RA and right lobe posterior (RP) segments in Group I. Additionally, there was no correlation between fibrosis scores and ADC in Group I, whereas there was a negative correlation between fibrosis scores and ADC values of the LL (28.3%) and RP (29.5%). CONCLUSION: CH patients had lower ADC values. There was no correlation between ADC values and fibrosis stages or ADC and HAI values. Quantitative DW-MRI was not useful in determining the degree of fibrosis in liver tissue.