Diffusion-weighted imaging of soft tissue tumors: usefulness of the apparent diffusion coefficient for differential diagnosis

PURPOSE: We evaluated the efficacy of using the apparent diffusion coefficient (ADC) to differentiate soft tissue tumors. MATERIALS AND METHODS: We examined 88 histologically proven tumors (44 benign, 8 intermediate, 36 malignant) using diffusion-weighted magnetic resonance images. Images of the tumors were obtained using a single-shot, spin-echo type echo-planar imaging sequence. The tumors were classified histologically as myxoid or nonmyxoid. We then compared the ADC values of the myxoid and nonmyxoid tumors; the benign and malignant myxoid tumors; and the benign, intermediate, and malignant nonmyxoid tumors. RESULTS: The mean ADC value of the myxoid tumors (2.08 +/- 0.51 x 10(-3) mm(2)/s) was significantly greater than that of the nonmyxoid tumors (1.13 +/- 0.40 x 10(-3) mm(2)/s) (P < 0.001). There was no significant difference in the mean ADC values between benign myxoid tumors (2.10 +/- 0.50 x 10(-3) mm(2)/s) and malignant myxoid tumors (2.05 +/- 0.58 x 10(-3) mm(2)/s). The mean ADC value of benign nonmyxoid tumors (1.31 +/- 0.46 x 10(-3) mm(2)/s) was significantly higher than that of malignant nonmyxoid tumors (0.94 +/- 0.25 x 10(-3) mm(2)/s) (P < 0.001). CONCLUSION: The ADC value might be useful for diagnosing the malignancy of nonmyxoid soft tissue tumors.     

Apparent diffusion coefficient in malignant lymphoma and carcinoma involving cavernous sinus evaluated by line scan diffusion-weighted imaging

PURPOSE: To evaluate the apparent diffusion coefficient (ADC) of malignant lymphomas and carcinomas involving cavernous sinus by line scan diffusion-weighted imaging (LSDWI) and to determine the usefulness of this method for differentiating between the two tumors. MATERIALS AND METHODS: Four patients with malignant lymphomas and six patients with carcinomas were prospectively studied. LSDWI images were obtained with two different b values of 5 seconds/mm(2) and 1000 seconds/mm(2) in the coronal plane. The ADC values of the two types of tumors were calculated and compared. RESULTS: LSDWI provided diagnostic images with minimum susceptibility artifacts and enabled measurement of the ADC. The ADC value (mean +/- SD) was 0.51 +/- 0.06 x 10(-3) mm(2)/second in malignant lymphomas and 0.99 +/- 0.08 x 10(-3) mm(2)/second in carcinomas. A significant difference in ADC values was found between the two (P < 0.01). CONCLUSION: Malignant lymphomas showed significantly lower ADC value than carcinomas. ADC provides additional useful information about differentiation between these tumors.     

Diffusion-weighted MRI in the characterization of soft-tissue tumors

PURPOSE: To explore the potential of perfusion-corrected diffusion-weighted magnetic resonance imaging (MRI) in characterizing soft-tissue tumors. METHODS AND MATERIALS: Diffusion-weighted MRI was performed in 23 histologically proven soft-tissue masses using a diffusion-weighted spin-echo sequence with diffusion gradient strengths yielding five b-values (0-701 seconds/mm(2)). True diffusion coefficients and perfusion fractions were estimated and compared with apparent diffusion coefficients (ADCs). RESULTS: ADC values of all tumors, subcutaneous fat, and muscle were significantly higher than true diffusion coefficients, indicating a contribution of perfusion to the ADC. True diffusion coefficients of malignant tumors (1.08 x 10(-3) mm(2)/second) were significantly lower than those of benign masses (1.71 x 10(-3) mm(2)/second), whereas ADC values between these groups were not significantly different. CONCLUSION: Perfusion-corrected diffusion-weighted MRI has potential in differentiating benign from malignant soft-tissue masses.     

Differentiation of clinically benign and malignant breast lesions using diffusion-weighted imaging

PURPOSE: To evaluate the value of diffusion-weighted imaging (DWI) in distinguishing between benign and malignant breast lesions. MATERIALS AND METHODS: Fifty-two female subjects (mean age = 58 years, age range = 25-75 years) with histopathologically proven breast lesions underwent DWI of the breasts with a single-shot echo-planar imaging (EPI) sequence using large b values. The computed mean apparent diffusion coefficients (ADCs) of the breast lesions and cell density were then correlated. RESULTS: The ADCs varied substantially between benign breast lesions ((1.57 +/- 0.23) x 10(-3) mm(2)/second) and malignant breast lesions ((0.97 +/- 0.20) x 10(-3) mm(2)/second). In addition, the mean ADCs of the breast lesions correlated well with tumor cellularity (P < 0.01, r = -0.542). CONCLUSION: The ADC would be an effective parameter in distinguishing between malignant and benign breast lesions. Further, tumor cellularity has a significant influence on the ADCs obtained in both benign and malignant breast tumors.     

Quantitative diffusion imaging in breast cancer: a clinical prospective study

PURPOSE: To study the correlation between apparent diffusion coefficient (ADC) and pathology in patients with undefined breast lesion, to validate how accurately ADC is related to histology, and to define a threshold value of ADC to distinguish malignant from benign lesions. MATERIALS AND METHODS: Seventy-eight patients (110 lesions) were referred for positive or dubious findings. Three-dimensional fast low-angle shot (3D-FLASH) with contrast injection was applied. EPI diffusion-weighted imaging (DWI) with fat saturation was performed, and ROIs were selected on subtraction 3D-FLASH images before and after contrast injection, and copied on an ADC map. Inter- and intraobserver analyses were performed. RESULTS: At pathology 22 lesions were benign, 65 were malignant, and 23 were excluded. The ADCs of malignant and benign lesions were statistically different. In malignant tumors the ADC was (mean +/- SEM) 0.95 +/- 0.027 x 10(-3)mm(2)/second, and in benign tumors it was 1.51 +/- 0.068 x 10(-3)mm(2)/second. According to receiver operating characteristic (ROC) curves, we found a threshold between malignant and benign lesions for highest sensitivity and specificity (both 86%) around 1.13 +/- 0.10 x 10(-3)mm(2)/second. For a threshold of 0.95 +/- 0.10 x 10(-3)mm(2)/second, specificity was 100% but sensitivity was very low. Inter- and intraobserver studies showed good reproducibility. CONCLUSION: The ADC may help to differentiate benign and malignant lesions with good specificity, and may increase the overall specificity of breast MRI.     

Head and neck lesions: characterization with diffusion-weighted echo-planar MR imaging

PURPOSE: To evaluate whether apparent diffusion coefficients (ADCs) calculated from diffusion-weighted echo-planar magnetic resonance (MR) images can be used to characterize head and neck lesions. MATERIALS AND METHODS: Diffusion-weighted echo-planar MR imaging was performed with a 1.5-T MR unit in 97 head and neck lesions in 97 patients. Images were obtained with a diffusion-weighted factor, factor b, of 0, 500, and 1,000 sec/mm(2), and an ADC map was constructed. The ADCs of lesions, cerebrospinal fluid, and spinal cord were calculated. RESULTS: Acceptable images for ADC measurement were obtained in 81 (84%) patients. The mean ADC of malignant lymphomas, (0.66 +/- 0.17[SD]) x 10(-3) mm(2)/sec (n = 13), was significantly smaller (P <.001) than that of carcinomas. The mean ADC of carcinomas, (1.13 +/- 0.43) x 10(-3) mm(2)/sec (n = 36), was significantly smaller (P =.002) than that of benign solid tumors. The mean ADC of benign solid tumors, (1.56 +/- 0.51) x 10(-3) mm(2)/sec (n = 22), was significantly smaller (P =.035) than that of benign cystic lesions, (2.05 +/- 0.62) x 10(-3) mm(2)/sec (n = 10). No significant differences were seen in the mean ADC of cerebrospinal fluid and of spinal cord among four groups of lesions. When an ADC smaller than 1.22 x 10(-3) mm(2)/sec was used for predicting malignancy, the highest accuracy of 86%, with 84% sensitivity and 91% specificity, was obtained. CONCLUSION: Measurement of ADCs may be used to characterize head and neck lesions.     

The role of diffusion-weighted imaging and the apparent diffusion coefficient (ADC) values for breast tumors.

OBJECTIVE: We wanted to evaluate the role of diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) for detecting breast tumors, as compared with the T1- and T2-weighted images. MATERIALS AND METHODS: Forty-one female patients underwent breast MRI, and this included the T1-, T2-, DWI and dynamic contrast-enhanced images. Sixty-five enhancing lesions were detected on the dynamic contrast-enhanced images and we used this as a reference image for detecting tumor. Fifty-six breast lesions were detected on DWI and the histological diagnoses were as follows: 43 invasive ductal carcinomas, one mucinous carcinoma, one mixed infiltrative and mucinous carcinoma, seven ductal carcinomas in situ (DCIS), and four benign tumors. First, we compared the detectability of breast lesions on DWI with that of the T1- and T2-weighted images. We then compared the ADCs of the malignant and benign breast lesions to the ADCs of the normal fibroglandular tissue. RESULTS: Fifty-six lesions were detected via DWI (detectability of 86.2%). The detectabilities of breast lesions on the T1- and T2-weighted imaging were 61.5% (40/65) and 75.4% (49/65), respectively. The mean ADCs of the invasive ductal carcinoma (0.89+/-0.18 x 10(-3)mm(2)/second) and DCIS (1.17+/-0.18 x 10(-3)mm(2)/ second) are significantly lower than those of the benign lesions (1.41+/-0.56 x 10(-3)mm(2)/second) and the normal fibroglandular tissue (1.51+/-0.29 x 10(-3)mm(2)/ second). CONCLUSION: DWI has a high sensitivity for detecting breast tumors, and especially for detecting malignant breast tumors. DWI was an effective imaging technique for detecting breast lesions, as compared to using the T1- and T2-weighted images.     

Usefulness of the apparent diffusion coefficient in line scan diffusion-weighted imaging for distinguishing between squamous cell carcinomas and malignant lymphomas of the head and neck

BACKGROUND AND PURPOSE: Squamous cell carcinoma (SCC) and lymphoma are common malignant tumors of the head and neck. The purpose of this study was to determine whether the apparent diffusion coefficient (ADC) in line scan diffusion-weighted imaging (LSDWI) is useful for distinguishing between SCC and lymphoma of the head and neck. METHODS: LSDWI was prospectively performed in 39 patients with SCC and in 14 patients with lymphoma. Images were obtained with a diffusion-weighted factor (b factor) of 5 and 1000 s/mm(2), and ADC maps were generated. ADC values were measured for the two types of tumor. RESULTS: Mean ADC values were 0.96 +/- 0.11 x 10(-3) mm(2)/s for SCC and 0.65 +/- 0.09 x 10(-3) mm(2)/s for lymphoma; the difference was significant (P < .001). All but one of the patients with lymphoma had ADC values lower than the lowest ADC (0.76 x 10(-3) mm(2)/s) in patients with SCC. When an ADC of 0.76 x 10(-3) mm(2)/s was used to distinguish between SCC and lymphoma, accuracy was 98% (52 of 53 lesions). CONCLUSION: ADC values appear to be useful for distinguishing between SCC and lymphoma in the head and neck.     

Usefulness of the calculated apparent diffusion coefficient value in the differential diagnosis of retroperitoneal masses

PURPOSE: To elucidate whether or not the apparent diffusion coefficient (ADC) values calculated from echo-planar diffusion-weighted (EPDW) MR images are useful in the differential diagnosis of retroperitoneal masses. MATERIALS AND METHODS: In 50 patients with known retroperitoneal masses, EPDW images were performed with b-factors of 0-1100 seconds/mm2. The final histologic diagnoses of these lesions were as follows: 12 malignant lymphomas, four other malignant mesenchymal neoplasms, 25 malignant epithelial neoplasms, seven benign mesenchymal neoplasms, and two nonneoplastic lesions. The ADC values obtained for the solid portion of the lesions were used to represent each lesion, and the values of the histologic groups were compared. RESULTS: The respective value of ADC for 12 malignant lymphomas, four other mesenchymal neoplasms, seven benign mesenchymal neoplasms, and two nonneoplastic lesions were as follows: 0.66 +/- 0.26, 1.26 +/- 0.50, 0.90 +/- 0.20, 1.87 +/- 0.48, 1.32 +/- 0.20 x 10(-3) mm2/second. The ADC value of the malignant lymphoma was significantly lower than that of the other malignant mesenchymal lesions, and was also lower than the ADC of the benign lesions. The ADC value of the malignant epithelial neoplasms was lower than that of the benign mesenchymal tumors. The ADC values of the malignant and benign lesions were 0.94 +/- 0.30 and 1.75 +/- 0.49 x 10(-3) mm2/second, respectively, which also demonstrated a significant difference. CONCLUSION: ADC values calculated from EPDW MR images may provide useful information in the differential diagnosis of retroperitoneal masses.     

Evaluation of liver diffusion isotropy and characterization of focal hepatic lesions with two single-shot echo-planar MR imaging sequences: prospective study in 66 patients

PURPOSE: To (a) evaluate liver diffusion isotropy, (b) compare two diffusion-weighted magnetic resonance (MR) imaging sequences for the characterization of focal hepatic lesions by using two or four b values, and (c) determine an apparent diffusion coefficient (ADC) threshold value to differentiate benign from malignant lesions. MATERIALS AND METHODS: Sixty-six patients were examined with two single-shot echo-planar diffusion-weighted MR sequences. In the first sequence, liver diffusion isotropy was evaluated by using diffusion gradients in three directions with two b values. In the second sequence, a unidirectional diffusion gradient was used with four b values. ADCs were measured in 43 patients with 52 focal hepatic lesions more than 1 cm in diameter and in 23 patients with 14 normal and nine cirrhotic livers and were compared by using nonparametric tests. RESULTS: Diffusion in the liver parenchyma was isotropic. ADCs of focal hepatic lesions were significantly different between sequences (P <.01). The mean (+/- SD) ADCs in the first sequence were 0.94 x 10(-3) mm(2)/sec +/- 0.60 for metastases, 1.33 x 10(-3) mm(2)/sec +/- 0.13 for HCCs, 1.75 x 10(-3) mm(2)/sec +/- 0.46 for benign hepatocellular lesions, 2.95 x 10(-3) mm(2)/sec +/- 0.67 for hemangiomas, and 3.63 x 10(-3) mm(2)/sec +/- 0.56 for cysts. There was a significant difference between benign (2.45 x 10(-3) mm(2)/sec +/- 0.96, isotropic value) and malignant (1.08 x 10(-3) mm(2)/sec +/- 0.50) lesions (P <.01 for both sequences). CONCLUSION: Diffusion-weighted MR imaging can help differentiate benign from malignant hepatic lesions. The use of two b values in one direction could be sufficient for the design of MR sequences in the liver.     

Diffusion-weighted single-shot echoplanar MR imaging for liver disease.

OBJECTIVE: The aims of this study were to determine apparent diffusion coefficients (ADCs) of the abdominal organs and liver lesions, to determine the effect of the magnitude of b values on the ADCs, and to determine whether measured ADCs of liver tumors help differentiate benign from malignant lesions. SUBJECTS AND METHODS: Six healthy volunteers and 126 patients were examined with diffusion-weighted single-shot echo-planar imaging using multiple b values (maximum, 846 sec/mm2). The ADCs of the liver, spleen, kidney, 49 malignant liver lesions (33 hepatocellular carcinomas, 15 metastatic liver tumors, and one cholangiocellular carcinoma), and 30 benign lesions (17 cysts, 12 hemangiomas, and one angiomyolipoma) were calculated. RESULTS: The ADCs of the abdominal organs and liver lesions showed smaller values when calculated with the greater maximum b values. The ADCs of the benign lesions calculated with all the b values of less than 850 sec/mm2 (2.49+/-1.39 x 10(-3) mm2/sec) were significantly (p = .0024) greater than those of the malignant lesions (1.01+/-0.38 x 10(-3) mm2/sec). When the maximum b value is 846 sec/mm2, use of a threshold ADC of 1.6 x 10(-3) mm2/sec would result in a sensitivity of 98% and a specificity of 80% for differentiation of malignant liver lesions from benign lesions. CONCLUSION. Measurement of ADC has good potential for characterizing liver lesions, but the calculated ADCs could be affected by the magnitude of the maximum b value.     

Endorectal diffusion-weighted imaging in prostate cancer to differentiate malignant and benign peripheral zone tissue

PURPOSE: To determine if the apparent diffusion coefficient (ADC) can discriminate benign from malignant peripheral zone (PZ) tissue in patients with biopsy-proven prostate cancer that have undergone endorectal diffusion-weighted imaging (DWI) of the prostate. MATERIALS AND METHODS: Ten patients with prostate cancer underwent endorectal magnetic resonance imaging (MRI) in addition to DWI. A two-dimensional grid was placed over the axial images, and each voxel was graded by a 4-point rating scale to discriminate nonmalignant from malignant PZ tissue based on MR images alone. ADC was then determined for each voxel and plotted for nonmalignant and malignant voxels for the entire patient set. Second, with the radiologist aware of biopsy locations, any previously assigned voxel grade that was inconsistent with biopsy data was regrouped and ADCs were replotted. RESULTS: For the entire patient set, without and with knowledge of the biopsy data, the mean ADCs for nonmalignant and malignant tissue were 1.61 +/- 0.27 and 1.34 +/- 0.38 x 10(-3) mm2/second (P = 0.002) and 1.61 +/- 0.26 and 1.27 +/- 0.37 x 10(-3) mm2/second (P = 0.0005), respectively. CONCLUSION: DWI of the prostate is possible with an endorectal coil. The mean ADC for malignant PZ tissue is less than nonmalignant tissue, although there is overlap in individual values.     

Relevance of b-values in evaluating liver fibrosis: a study in healthy and cirrhotic subjects using two single-shot spin-echo echo-planar diffusion-weighted sequences

PURPOSE: To investigate the relevance of increasing b-values in evaluating liver fibrosis through the agreement of two diffusion-weighted (DW) sequences. MATERIALS AND METHODS: A total of 29 cirrhotic patients and 29 healthy volunteers were studied on a 1.5T system. Two single-shot spin-echo echo-planar sequences were acquired using sets of increasing b-values: 0, 150, 250, and 400 seconds/mm(2) (first sequence: DW1a) and 0, 150, 250, 400, 600, and 800 seconds/mm(2) (second sequence: DW2a). Apparent diffusion coefficients (ADCs) of the hepatic parenchyma were calculated on ADC maps. Noise-scaled single-point ADCs were calculated for each sequence from b = 400 seconds/mm(2). RESULTS: ADCs resulted significantly lower in cirrhotic patients compared to controls using both DW1a (mean 1.14 +/- 0.20 x 10(-3)mm(2)/second vs. 1.54 +/- 0.12 x 10(-3)mm(2)/second; P < 0.0001) and DW2a (mean 0.91 +/- 0.18 x 10(-3)mm(2)/second vs. 1.04 +/- 0.18 x 10(-3)mm(2)/second; P = 0.0089). DW1 and DW2, respectively significantly differed in diagnostic performance at receiver operating characteristic (ROC) curve analysis (P = 0.003), showing AUCs of 0.93 (sensitivity 89.7%, specificity 100%) and 0.73 (sensitivity 62.1%, specificity 79.3%), respectively. Noise-scaled single-point ADCs showed a progressive convergence to similar values in cirrhotic and healthy livers at b = 800 seconds/mm(2) (1.12 +/- 0.27 x 10(-3)mm(2)/second vs. 1.13 +/- 0.17 x 10(-3)mm(2)/second). CONCLUSION: A DW sequence is accurate in assessing liver fibrosis using intermediate (400 seconds/mm(2)) rather than high (800 seconds/mm(2)) maximum b-values, but after proper recalculation of ADCs the effects of perfusion rather than diffusion should be considered responsible for the higher accuracy at lower b-values.     

In vivo measurement of the apparent diffusion coefficient in normal and malignant prostatic tissues using echo-planar imaging

PURPOSE: To measure for the first time the apparent diffusion coefficient (ADC) values in anatomical regions of the prostate for normal and patient groups, and to investigate its use as a differentiating parameter between healthy and malignant tissue within the patient group. MATERIALS AND METHODS: Single-shot diffusion-weighted echo-planar imaging (DW-EPI) was used to measure the ADC in the prostate in normal (N = 7) and patient (N = 19) groups. The spin-echo images comprised 96 x 96 pixels (field of view of 16 cm, TR/TE = 4000/120 msec) with six b-factor values ranging from 64 to 786 seconds/mm(2). RESULTS: The ADC values averaged over all patients in non-cancerous and malignant peripheral zone (PZ) tissues were 1.82 +/- 0.53 x 10(-3) (mean +/- SD) and 1.38 +/- 0.52 x 10(-3) mm(2)/second, respectively (P = 0.00045, N = 17, paired t-test). The ADC values were found to be higher in the non-cancerous PZ (1.88 +/- 0.48 x 10(-3)) than in healthy or benign prostatic hyperplasia central gland (BPH-CG) region (1.62 +/- 0.41 x 10(-3)). For the normal group, the mean values were 1.91 +/- 0.46 x 10(-3) and 1.63 +/- 0.30 x 10(-3) mm(2)/second for the PZ and CG, respectively (P = 0.011, N = 7). Significant overlap exists between individual values among all tissue types. Furthermore, ADC values for the same tissue type showed no statistically significant difference between the two subject groups. CONCLUSION: ADC is quantified in the prostate using DW-EPI. Values are lower in cancerous than in healthy PZ in patients, and in BPH-CG than PZ in volunteers.     

Apparent diffusion coefficient mapping of salivary gland tumors: prediction of the benignancy and malignancy

BACKGROUND AND PURPOSE: Preoperative prediction of tumor malignancy is clinically very important, because this information strongly influences the surgical plan. We evaluate the preoperative apparent diffusion coefficient (ADC) maps of benign and malignant salivary gland tumors. MATERIALS AND METHODS: High-resolution MR imaging was performed on 31 patients with benign or malignant salivary gland tumors; ADC maps of the tumors were also obtained. Surface coils of 47 or 110 mm diameter were used to improve the image resolution. The ADCs were compared with histologic features of the excised tumors. RESULTS: The ADC maps effectively depicted the histologic features of the salivary gland tumors, such as presence of cancer cells, myxomatous tissues, fibrosis, necrosis, cyst formation, and lymphoid tissues. The ADC maps showed that more frequent areas with high ADCs (> or = 1.8 x 10(-3) mm(2)/s) were significantly greater in benign tumors than in malignant tumors. The sensitivity and specificity for high ADC occupying fewer than 5% of the area of a tumor was 89% and 100%, respectively, resulting in 97% accuracy, 100% positive predictive value, and 96% negative predictive value. CONCLUSION: The ADC may provide preoperative tissue characterization of the salivary gland tumors.     

Evaluation of diffusion-weighted imaging for the differential diagnosis of poorly contrast-enhanced and T2-prolonged bone masses: Initial experience

PURPOSE: To determine whether quantitative diffusion-weighted imaging (DWI) is useful for characterizing poorly contrast-enhanced and T2-prolonged bone masses. MATERIALS AND METHODS: We studied 20 bone masses that showed high signal intensity on T2-weighted images and poor enhancement on contrast-enhanced T1-weighted images. These included eight solitary bone cysts, five fibrous dysplasias, and seven chondrosarcomas. To analyze diffusion changes we calculated the apparent diffusion coefficient (ADC) for each lesion. RESULTS: The ADC values of the two types of benign lesions and chondrosarcomas were not significantly different. However, the mean ADC value of solitary bone cysts (mean +/-SD, 2.57 +/- 0.13 x 10(-3) mm(2)/second) was significantly higher than that of fibrous dysplasias and chondrosarcomas (2.0 +/- 0.21 x 10(-3) mm(2)/second and 2.29 +/- 0.14 x 10(-3) mm(2)/second, respectively, P < 0.05). None of the lesions with ADC values lower than 2.0 x 10(-3) mm(2)/second were chondrosarcomas. CONCLUSION: Although there was some overlapping in the ADC values of chondrosarcomas, solitary bone cyst, and fibrous dysplasia, quantitative DWI may aid in the differential diagnosis of poorly contrast-enhanced and T2-prolonged bone masses.     

Diffusion-weighted imaging of the prostate at 3 T for differentiation of malignant and benign tissue in transition and peripheral zones: preliminary results

OBJECTIVE: To evaluate prospectively the use of apparent diffusion coefficients (ADCs) for the differentiation of malignant and benign tissue in the transition (TZ) and peripheral (PZ) zones of the prostate diffusion-weighted imaging (DWI) at 3 T magnetic resonance imaging (MRI) using a phased-array coil. METHODS: The DWI at 3-T MRI was performed on a total of 35 patients before radical prostatectomy. A single-shot echo-planar imaging DWI technique with b = 0 and b = 1000 s/mm2 was used. The ADC values were measured in both benign and malignant tissues in the PZ and TZ using regions of interest. Differences between PZ and TZ ADC values were estimated using a paired Student t test. Presumed ADC cutoff values in the PZ and TZ for the diagnosis of cancer were assessed by receiver operating characteristic analysis. RESULTS: The ADC values of malignant tissues were significantly lower than those of benign tissues in the PZ and TZ (P < 0.001; 1.32 +/- 0.24 x 10(-3) mm2/s vs 1.97 +/- 0.25 x 10(-3) mm2/s, and 1.37 +/- 0.29 x 10(-3) mm2/s vs 1.79 +/- 0.19 x 10(-3) mm2/s, respectively). For tumor diagnosis, cutoff values of 1.67 x 10(-3) mm2/s (PZ) and 1.61 x 10(-3) mm2/s (TZ) resulted in sensitivities and specificities of 94% and 91% and 90% and 84%, respectively. CONCLUSIONS: The DWI of the prostate at 3T MRI using a phased-array coil was useful for the differentiation of malignant and benign tissues in the TZ and PZ.     

CT and radiography of bacterial respiratory infections in AIDS patients

OBJECTIVE: Acute vertebral collapse is common, and it is sometimes difficult to determine whether the cause is benign or malignant. Recently, diffusion-weighted imaging has been reported to be useful for differentiating the two types. The purpose of this study was to evaluate diffusion abnormalities quantitatively in benign and malignant compression fractures using line scan diffusion-weighted imaging. SUBJECTS AND METHODS. Line scan diffusion-weighted imaging was prospectively performed in 17 patients with 20 acute vertebral compression fractures caused by osteoporosis or trauma, in 12 patients with 16 vertebral compression fractures caused by malignant tumors, and in 35 patients with 47 metastatic vertebrae without collapse. Images were obtained at b values of 5 and 1,000 sec/mm(2). The apparent diffusion coefficient (ADC) was measured in vertebral compression fractures and metastatic vertebrae without collapse. RESULTS: The ADC (mean +/- SD) was 1.21 +/- 0.17 x 10(-3) mm(2)/sec in benign compression fractures, 0.92 +/- 0.20 x 10(-3) mm(2)/sec in malignant compression fractures, and 0.83 +/- 0.17 x 10(-3) mm(2)/sec in metastatic vertebral lesions without collapse. The ADC was significantly higher in benign compression fractures than in malignant compression fractures (p < 0.01), although the two types showed considerable overlap. CONCLUSION: Although the quantitative assessment of vertebral diffusion provides additional information concerning compressed vertebrae, the benign and malignant compression fracture ADC values overlap considerably. Therefore, even a quantitative vertebral diffusion assessment may not always permit a clear distinction between benign and malignant compression fractures.     

Comparison between malignant and benign abdominal lymph nodes on diffusion-weighted imaging

RATIONALE AND OBJECTIVES: The purpose of this study is to review the apparent diffusion coefficient (ADC) values of benign and metastatic abdominal lymph nodes on diffusion-weighted imaging (DWI). MATERIALS AND METHODS: Twenty-eight patients with a total of 40 benign (20 patients) and 16 malignant (8 patients) lymph nodes who underwent DWI MRI of the abdomen (b = 0.600) were enrolled in the study. ADC values of the lymph nodes were measured and comparison was made between benign and malignant groups. RESULTS: Mean ADC value of lymph nodes was 2.38 +/- 0.29 and 1.84 +/- 0.37 x 10(-3) mm(2)/sec in the benign and malignant groups, respectively. There was a significant statistical difference between the ADC values of benign and malignant lymph nodes (P < .0005). CONCLUSION: A wide range of ADC values exist in patients with metastatic abdominal lymph nodes, with a tendency of higher ADC values in benign lymph nodes.     

Diffusion-weighted imaging of normal and malignant prostate tissue at 3.0T

PURPOSE: To measure the apparent diffusion coefficient (ADC) of normal and malignant prostate tissue at 3.0T using a phased-array coil and parallel imaging, and determine the utility of ADC values in differentiating tumor from normal peripheral zone (PZ). MATERIALS AND METHODS: ADC values were calculated for 49 patients (tumor and PZ) with evidence of prostate cancer. Additionally, for nine asymptomatic volunteers, ADC values were determined for apparently normal central gland and PZ. A single-shot EPI diffusion-weighted imaging (DWI) technique with b = 0 and 500 seconds/mm2 was employed. RESULTS: ADC values were significantly lower for tumor (1.38 +/- 0.32 x 10(-3) mm2/second) than for patient PZ (1.95 +/- 0.50 x 10(-3) mm2/second, P < 0.001) and volunteer PZ (1.60 +/- 0.25 x 10(-3) mm2/second, P = 0.031). A considerable overlap of ADC values was noted between patient tissue types. CONCLUSION: DWI of the prostate at 3.0T in conjunction with a phased-array coil and parallel imaging allows ADC calculation of the prostate. ADC values were lower for tumors compared to normal-appearing PZ; however, there was considerable intersubject variability.