Biphasic time course of brain water ADC observed during the first month of life in term neonates with severe perinatal asphyxia is indicative of poor outcome at 3 years

In severe perinatal asphyxia, the prognostic value of apparent diffusion coefficient (ADC) measurements is still open to question. We hypothesized that temporal and anatomical changes of brain ADC values occurring early after the hypoxic-ischemic insult could predict the outcome at 36 months. To demonstrate this, mean ADC values were calculated for 16 brain structures in 59 term neonates who underwent an MR examination during the first month of life. Neonates were divided into two groups according to their 36-month outcome: unfavorable (death/severe disability) or favorable outcome. ADC values were plotted against age at scan.In neonates with favorable outcomes (n=32), ADC values were constant over the study period. In babies with unfavorable outcomes (n=27), ADCs exhibited two different patterns. In infratentorial structures, ADCs were constant and normal. In supratentorial areas, ADCs followed a biphasic temporal evolution: ADC values were at their lowest at day 2, showed a rapid increase until Days 5-7, and were thereafter similar to those of neonates with favorable outcomes. Using receiver operating characteristic analysis, during the first 3-5 days of life, all neonates with decreased ADC had an unfavorable outcome.These temporal and anatomical changes of ADC values imply that individual prognosis of asphyxiated neonates can only be predicted by measurement of ADC in supratentorial areas within the first 3-5 days of life.     

Carcinosarcoma of the uterus: radiologic-pathologic correlations with magnetic resonance imaging including diffusion-weighted imaging

The authors describe the MRI findings, including diffusion-weighted imaging findings, of histopathologically proven uterine carcinosarcoma in four postmenopausal women. In three of four patients, diffusion-weighted images clearly revealed hypointense areas corresponding to hypocellular regions caused by intratumoral necrosis, and apparent diffusion coefficient (ADC) mapping images indicated that necrotic areas had high ADC values. In the remaining patient, diffusion-weighted and ADC mapping images clearly distinguished components of adenocarcinoma from sarcoma. In all patients, diffusion-weighted and ADC mapping images precisely reflected histopathological findings. Diffusion-weighted images were found to demonstrate complicated tissue components in carcinosarcomas of the uterus, and thus, which may be useful for the diagnosis of this disease.     

Diffusion characteristics of large molecules assessed by proton MRS on a whole-body MR system

Methods for examinations of diffusion of large molecules of the size of fatty acids or triglycerides were developed for whole body MR units. Samples of aliphatic molecules were examined to study the influence of chain length. Feasibility under in vivo conditions was tested on lard samples at 37 degrees C and on human subjects Three stimulated echo sequences with maximum b-values of 2000 s/mm(2), 20000 s/mm(2), and 80000 s/mm(2) were used to assess a wide range of mobility. Sequence timing was optimized to minimize relaxation losses of fatty tissue. Apparent diffusion coefficients (ADC) were determined from five spectra with different diffusion weighting. In-vitro experiments were performed on butanol, decanol, and oleic acid to study the influence of chain length. In vivo conditions were mimicked using lard at 37 degrees C representing a composition of substances of various chain lengths. Subcutaneous fat and tibial bone marrow were studied in three healthy volunteers. ADC of muscular lipids of the lower leg was determined in two subjects. ADC values of pure aliphatic substances were in the range between 3.2 x 10(-5) mm(2)/s for oleic acid and 37.8 x 10(-5) mm(2)/s for butanol. In vivo investigations revealed ADC values of 1.11-1.24 x 10(-5) mm(2)/s for tibial bone marrow and 1.21-2.05 x 10(-5) mm(2)/s for subcutaneous fat. Diffusion coefficients of extra- and intramyocellular lipids were 1.83-3.65 x 10(-5) mm(2)/s and 2.22-3.60 x 10(-5) mm(2)/s, respectively. The proposed technique enables determination of ADC values of relatively large molecules and of lipid tissue compartments under in vivo conditions. Diffusion properties in several human lipid compartments are reported for the first time. Incoherent voxel motion influences the in vivo results to an unknown degree because of high motion sensitivity. In vitro experiments revealed ADC values depending on the chain length of the substances, indicating a residual dependence of measured ADC's on sequence timing.     

Abdominal apparent diffusion coefficient measurements: effect of diffusion-weighted image quality and usefulness of anisotropic images

This study aimed to assess the effect of diffusion-weighted image (DWI) quality on abdominal apparent diffusion coefficient (ADC) measurements and the usefulness of anisotropic images. Twenty-six patients (10 men and 16 women; mean, 58.1 years) who underwent DW imaging and were diagnosed not to have any abdominal diseases were analyzed. Single-shot spin-echo echo-planar DW imaging was performed, and one isotropic and three orthogonal anisotropic images were created. ADCs were calculated for liver (four segments), spleen, pancreas (head, body, tail) and renal parenchyma. Image quality for each organ part was scored visually. We estimated the correlation between ADC and image quality and evaluated the feasibility of using anisotropic images. ADCs and image quality were affected by motion probing gradient directions in the liver and pancreas. A significant inverse correlation was found between ADC and image quality. The r values for isotropic images were −.46, −.48, −.70 and −.28 for the liver, spleen, pancreas and renal parenchyma, respectively. Anisotropic images had the best quality and lowest ADC in at least one organ part in 17 patients. DWIs with the best quality among isotropic and anisotropic images should be used in the liver and pancreas.     

Pediatric abdominal masses: diagnostic accuracy of diffusion weighted MRI

Purpose

To retrospectively identify apparent diffusion coefficient (ADC) values of pediatric abdominal mass lesions, to determine whether measured ADC of the lesions and signal intensity on diffusion-weighted (DW) images allow discrimination between benign and malignant mass lesions.

Materials and Methods

Approval for this retrospective study was obtained from the institutional review board. Children with abdominal mass lesions, who were examined by DW magnetic resonance imaging (MRI) were included in this study. DW MR images were obtained in the axial plane by using a non breath-hold single-shot spin-echo sequence on a 1.5-T MR scanner. ADCs were calculated for each lesion. ADC values were compared with Mann–Whitney U test. Receiver operating characteristic curve analysis was performed to determine cut-off values for ADC. The results of visual assessment on b800 images and ADC map images were compared with chi-square test.

Results

Thirty-one abdominal mass lesions (16 benign, 15 malignant) in 26 patients (15 girls, 11 boys, ranging from 2 days to 17 years with 6.9 years mean) underwent MRI. Benign lesions had significantly higher ADC values than malignant ones (P<.001). The mean ADCs of malignant lesions were 0.84±1.7×10⁻³ mm²/s, while the mean ADCs of the benign ones were 2.28±1.00×10⁻³ mm²/s. With respect to cutoff values of ADC: 1.11×10⁻³ mm²/s, sensitivity and negative predictive values were 100%, specificity was 78.6% and positive predictive value was 83.3%. For b800 and ADC map images, there were statistically significant differences on visual assessment. All malignant lesions had variable degrees of high signal intensity whereas eight of the 16 benign ones had low signal intensities on b800 images (P<.001). On ADC map images, all malignant lesions were hypointense and most of the benign ones (n=11, 68.7%) were hyperintense (P<.001).

Conclusion

DW imaging can be used for reliable discrimination of benign and malignant pediatric abdominal mass lesions based on considerable differences in the ADC values and signal intensity changes.     

氮对金刚石缺陷发光的影响

利用低温显微荧光光谱研究了IIa型、Ib型、Ia型金刚石的缺陷发光性质. 研究发现, 随着氮含量增加, 间隙原子及空位逐渐被氮原子所束缚, 从而使得GR1中心、533.5 nm及580 nm中心等本征缺陷发光减弱, 而氮-空位复合缺陷(NV中心)及523.7 nm中心等氮相关缺陷发光增强. 高温退火后, 间隙原子与空位可以自由移动, IIa型金刚石中出现了NV⁰中心, Ib型金刚石中只剩下了NV中心, Ia型金刚石中氮原子之间发生团聚, 出现了H3中心及N3中心. 另外, 氮作为施主原子, 有利于负电荷缺陷的形成, 如3H 中心、NV^- 中心.     

Diffusion-weighted MRI in prostate cancer -- comparison between single-shot fast spin echo and echo planar imaging sequences

Diffusion-weighted (DW) MRI at 1.5 T was carried out in two groups of patients. MRI data were correlated with the biopsy and histopathology (where available). The performance of two sequences -- a single-shot FSE (14 patients) and a single-shot EPI (15 patients) -- was compared. Average ADC values from the normal peripheral zone (PZ), central gland (CG) and the tumour [prostate carcinoma (PCa)] were calculated from b values of 0 and 600. Tukey-Kramer test was used for statistical analysis. EPI produced higher values of ADC (10(-3) mm(2)/s) than FSE sequence: 1.992+/-0.208 vs. 1.573+/-0.270 in PZ (P<.001), 1.518+/-0.126 vs. 1.373+/-0.179 in CG and 1.214+/-0.254 vs. 0.993+/-0.158 in PCa (P<.01). In conclusion, both EPI and FSE sequences showed differences in ADC between normal PZ, CG and PCa; however, EPI produced significantly higher ADC values than FSE.     

Repeatability of echo-planar-based diffusion measurements of the human prostate at 3 T

Echo-planar-based diffusion-weighted imaging (DWI) of the prostate is increasingly being suggested as a viable technique, complementing information derived from conventional magnetic resonance imaging methods for use in tissue discrimination. DWI has also been suggested as a potentially useful tool in the assessment of tumor response to treatment. In this study, the repeatability of apparent diffusion coefficient (ADC) values obtained from both DWI and diffusion tensor imaging (DTI) has been assessed as a precursor to determining the magnitude of treatment-induced changes required for reliable detection. The repeatability values of DWI and DTI were found to be similar, with ADC values repeatable to within 35% or less over a short time period of a few minutes and a longer time period of a month. Fractional anisotropy measurements were found to be less repeatable (between 26% and 71%), and any changes duly recorded in longitudinal studies must therefore be treated with a degree of caution.     

The value of diffusion-weighted MRI to evaluate the response to radiochemotherapy for cervical cancer

Purpose

To investigate the value of apparent diffusion coefficient (ADC) to predict and monitor the therapy response for cervical cancer patients receiving concurrent radiochemotherapy, and to analyze the influence of different b-value combinations on ADC-based evaluation of treatment response.

Material and Methods

Seventy-five cervical cancer patients treated with radiochemotherapy received conventional MRI and DWI prior to therapy, after 2 weeks of therapy, after four weeks of therapy and after therapy completion. Treatment response was classified as complete response (CR, n = 35), partial response (PR, n = 22) and stable disease (SD, n = 18), which was determined according to final tumor size after 6 months of therapy completion. Dynamic changes of apparent diffusion coefficients (ADC) and tumor size in the three tumor groups were observed and compared. All the ADCs were calculated from b = 0, 600 s/mm² and b = 0, 1000 s/mm².

Results

The ADC increased percentage was higher in CR group than those in PR and SD groups after two weeks and four weeks of therapy, with significant differences in absolute ADCs between CR and PR, SD groups after therapy completion; the overall discriminatory capability for differentiation of CR and PR, SD groups was higher for high b-value combination (0, 1000 s/mm²) than for low b-value combination (0, 600 s/mm²).

Conclusion

DWI can be used as a predictive and monitoring biomarker of treatment response to radiochemotherapy in patients with cervical cancer. High b-value combination may be more reliable to evaluate the treatment response for cervical cancer.     

多孔介质体元内随机运动的核磁共振成像研究

多孔介质体元内随机运动的核磁共振成像是一种透视流体微观无规则运动的方法.在多孔介质中,存在两种无规则运动.一种是分于扩散.它是由于分子的布朗运动引起的;另一种是弥散,它是由多孔介质中毛管网络的复杂结构造成的.多孔介质中的液体弥散和分子扩散会在成像体无内产生相位分散.这种相位分散致使回波信号发生衰减.采用适当的梯度脉冲.可以从这种信号衰减中获得视扩散系数(ADC)的分布图像.本文作者在4.7T高场超导核磁共振成像系统上.采用特制的高梯度线圈获得了扩散和机扩散系数分布的图像.在水和丙酮模型中获得了扩散系教图像,其扩散系数值与标准值相符.在人体肾结石中获得了扩散系数分布图像,在不同流速下,获得了多孔介质中的视扩散系数分布图像.并分析了视扩散系数与速度的关系.在多孔介质中定量确定扩散系数和机扩散系数及其空间分布将会极大地提高核磁共振成像技术在渗流力学研究中的应用能力.     

Correlation between metabolite ratios and ADC values of prostate in men with increased PSA level

Proton magnetic resonance spectroscopic imaging (MRSI) and diffusion-weighted imaging (DWI) were carried out in men with increased prostate-specific antigen (PSA) level. Forty subjects [controls (Group I) and patients (Groups II and III with PSA >20 and 4-20 ng/ml, respectively)] were investigated using endorectal coil at 1.5 T prior to transrectal ultrasound (TRUS)-guided biopsy. Metabolite ratio [citrate/(choline+creatine)] and apparent diffusion coefficient (ADC) were calculated for identical voxels. In patients, voxels that showed lower metabolite ratio showed reduced ADC in the peripheral zone (PZ) of the prostate, and voxels with increased metabolite ratio showed higher ADC. Metabolite ratios were used to predict areas of malignancy if the ratio was <1.4 and if ADC value was <1.17 x 10(-3) mm(2)/s. Patients in Group II had lower metabolite ratio and ADC in the PZ compared to controls and Group III. All 13 were positive for malignancy in MR, while 12 of 13 were positive on TRUS-guided sextant biopsy. In Group III, certain voxels of PZ that showed reduced metabolite ratio also showed lower ADC. A positive correlation was observed between metabolite ratio and ADC. MR predicted areas of malignancy in PZ in 15 of 20 patients; however, only six were positive on TRUS-guided biopsy perhaps due to high false-negative rate of TRUS-guided biopsy. Results show positive correlation between MRSI and DWI and their potential in detection of malignancy, thereby improving the diagnosis especially in patients with PSA level of 4-20 ng/ml.     

Comparison of accuracy of intravoxel incoherent motion and apparent diffusion coefficient techniques for predicting malignancy of head and neck tumors using half-Fourier single-shot turbo spin-echo diffusion-weighted imaging

Purpose

To evaluate the use of the intravoxel incoherent motion (IVIM) technique in half-Fourier single-shot turbo spin-echo (HASTE) diffusion-weighted imaging (DWI), and to compare its accuracy to that of apparent diffusion coefficient (ADC) to predict malignancy in head and neck tumors.

Patients and methods

HASTE DW images of 33 patients with head and neck tumors (10 benign and 23 malignant) were evaluated. Using the IVIM technique, parameters (D, true diffusion coefficient; f, perfusion fraction; D*, pseudodiffusion coefficient) were calculated for each tumor. ADC values were measured over a range of b values from 0 to 1000 s/mm². IVIM parameters and ADC values in benign and malignant tumors were compared using Student's t test, receiver operating characteristics (ROC) analysis, and multivariate logistic regression modeling.

Results

Mean ADC and D values of malignant tumors were significantly lower than those of benign tumors (P < 0.05). Mean D* values of malignant tumors were significantly higher than those of benign tumors (P < 0.05). There was no significant difference in mean f values between malignant and benign tumors (P > 0.05). The technique of combining D and D* was the best for predicting malignancy; accuracy for this model was higher than that for ADC.

Conclusions

The IVIM technique may be applied in HASTE DWI as a diagnostic tool to predict malignancy in head and neck masses. The use of D and D* in combination increases the diagnostic accuracy in comparison with ADC.     

温度对Ib型和IIa型金刚石大单晶(100)表面特征的影响

本文在5.6 GPa, 1250–1340 ℃的条件下, 利用温度梯度法, 以FeNiMnCo 合金为触媒, 沿籽晶的(100)晶面成功合成了不同晶形的优质Ib型和IIa型金刚石大单晶. 利用激光拉曼附件显微镜, 分别对上述不同温度下合成的两类金刚石样品上表面(100)面的中心区域及棱角区域进行观察分析. 研究发现, Ib型和IIa型金刚石大单晶(100)晶面上从中心到棱角处黑色纹路的分布逐渐变黑变密集; 另外, 随着金刚石合成温度的升高, Ib型金刚石大单晶(100)面上黑色纹路由稀疏逐渐变稠密, 而IIa型金刚石大单晶的黑色纹路较为稀疏; Ib型金刚石大单晶的形貌特征表现为从低温晶体的不规则分布过渡到中温、高温晶体的典型树枝状分布. IIa型金刚石大单晶(100)面特征随温度变化规律与Ib型的类似. 这两类金刚石大单晶表面特征的差异可能是由于IIa 型金刚石具有比Ib型更小的生长速度和更少的氮含量. 最后, 对两类塔状金刚石大单晶进行拉曼光谱测试分析, 结果表明IIa型金刚石大单晶的品质较Ib型金刚石大单晶好.     

Technical evaluation of in vivo abdominal fat and IMCL quantification using MRI and MRSI at 3 T

OBJECTIVES: The objectives of this study were to develop protocols that measure abdominal fat and calf muscle lipids with magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), respectively, at 3 T and to examine the correlation between these parameters and insulin sensitivity. MATERIALS AND METHODS: Ten nondiabetic subjects [five insulin-sensitive (IS) subjects and five insulin-resistant (IR) subjects] were scanned at 3 T. Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were segmented semiautomatically from abdominal imaging. Intramyocellular lipids (IMCL) in calf muscles were quantified with single-voxel MRS in both soleus and tibialis anterior muscles and with magnetic resonance spectroscopic imaging (MRSI). RESULTS: The average coefficient of variation (CV) of VAT/(VAT+SAT) was 5.2%. The interoperator CV was 1.1% and 5.3% for SAT and VAT estimates, respectively. The CV of IMCL was 13.7% in soleus, 11.9% in tibialis anterior and 2.9% with MRSI. IMCL based on MRSI (3.8+/-1.2%) were significantly inversely correlated with glucose disposal rate, as measured by a hyperinsulinemic-euglycemic clamp. VAT volume correlated significantly with IMCL. IMCL based on MRSI for IR subjects was significantly greater than that for IS subjects (4.5+/-0.9% vs. 2.8+/-0.5%, P=.02). CONCLUSION: MRI and MRS techniques provide a robust noninvasive measurement of abdominal fat and muscle IMCL, which are correlated with insulin action in humans.     

Diffusion-weighted MRI: influence of intravoxel fat signal and breast density on breast tumor conspicuity and apparent diffusion coefficient measurements

Promising recent investigations have shown that breast malignancies exhibit restricted diffusion on diffusion-weighted imaging (DWI) and may be distinguished from normal tissue and benign lesions in the breast based on differences in apparent diffusion coefficient (ADC) values. In this study, we assessed the influence of intravoxel fat signal on breast diffusion measures by comparing ADC values obtained using a diffusion-weighted single shot fast spin-echo sequence with and without fat suppression. The influence of breast density on ADC measures was also evaluated. ADC values were calculated for both tumor and normal fibroglandular tissue in a group of 21 women with diagnosed breast cancer. There were systematic underestimations of ADC for both tumor and normal breast tissue due to intravoxel contribution from fat signal on non–fat-suppressed DWI. This ADC underestimation was more pronounced for normal tissue values (mean difference=40%) than for tumors (mean difference=27%, P<.001) and was worse in women with low breast tissue density vs. those with extremely dense breasts (P<.05 for both tumor and normal tissue). Tumor conspicuity measured by contrast-to-noise ratio was significantly higher on ADC maps created with fat suppression and was not significantly associated with breast density. In summary, robust fat suppression is important for accurate breast ADC measures and optimal lesion conspicuity on DWI.     

Development of an ADC radiation tolerance characterization system for the upgrade of the ATLAS LAr calorimeter

ATLAS LAr calorimeter will undergo its Phase-I upgrade during the long shutdown(LS2) in 2018, and a new LAr Trigger Digitizer Board(LTDB) will be designed and installed. Several commercial-off-the-shelf(COTS)multi-channel high-speed ADCs have been selected as possible backups of the radiation tolerant ADC ASICs for the LTDB. To evaluate the radiation tolerance of these backup commercial ADCs, we developed an ADC radiation tolerance characterization system, which includes the ADC boards, data acquisition(DAQ) board, signal generator,external power supplies and a host computer. The ADC board is custom designed for different ADCs, with ADC drivers and clock distribution circuits integrated on board. The Xilinx ZC706 FPGA development board is used as a DAQ board. The data from the ADC are routed to the FPGA through the FMC(FPGA Mezzanine Card)connector, de-serialized and monitored by the FPGA, and then transmitted to the host computer through the Gigabit Ethernet. A software program has been developed with Python, and all the commands are sent to the DAQ board through Gigabit Ethernet by this program. Two ADC boards have been designed for the ADC, ADS52J90 from Texas Instruments and AD9249 from Analog Devices respectively. TID tests for both ADCs have been performed at BNL, and an SEE test for the ADS52J90 has been performed at Massachusetts General Hospital(MGH). Test results have been analyzed and presented. The test results demonstrate that this test system is very versatile, and works well for the radiation tolerance characterization of commercial multi-channel high-speed ADCs for the upgrade of the ATLAS LAr calorimeter. It is applicable to other collider physics experiments where radiation tolerance is required as well.     

Differential MRI diagnosis between brain abscesses and necrotic or cystic brain tumors using the apparent diffusion coefficient and normalized diffusion-weighted images

Magnetic Resonance Diffusion-Weighted Imaging (DWI) has been reported to be helpful for the differential diagnosis between abscesses and cystic/necrotic brain tumors. However the number of patients is still limited, and the sensitivity and specificity of the method remain to be confirmed. The primary purpose of this study was to investigate a larger sample of patients, all investigated under the same experimental conditions, in order to obtain statistically significant data. Moreover, there is no consensus about the appropriate values of b required to use to make an accurate diagnosis from DWI. The secondary purpose of this study was to determine the discriminating threshold b values for raw diffusion-weighted images and for normalized diffusion-weighted images. On the basis of 14 abscesses, 10 high-grade gliomas and 2 metastases, we show that the calculation of accurate Apparent Diffusion Coefficient (ADC) values gives a specificity rate of 100%. Without ADC calculation, we show that image normalization is required to make an accurate differential diagnosis, and we highlight the ability of DWI to discriminate between brain abscesses and cystic/necrotic brain tumors using normalized signal intensity at lower b values (503 s/mm(2)) than usual.     

Correlation study between DKI and conventional DWI in brain and head and neck tumors

PurposeTo investigate the relationship between the Diffusion Kurtosis Imaging (DKI) parameters and conventional metrics provided by Diffusion-weighted imaging (DWI) in patients affected by Brain or Head and Neck (HN) cancer.MethodsTen patients affected by brain tumor and nine patients with HN tumor underwent a pre-treatment MR examination at 3 T. The largest tumor section was manually contoured by two expert neuroradiologists. The apparent diffusion coefficient (D_app) and apparent diffusional kurtosis (K_app) parameters were determined at the voxel level by using the DKI model, and compared to the apparent diffusion coefficient (ADC) and the tissue diffusion coefficient (D_mono) obtained from mono-exponential fitting methods. The Akaike Information Criteria (AIC) was calculated to assess the quality of the fitting methods. Cross-correlations between all the variables were assessed using the Spearman rank test.ResultsIncreased K_app values were found in each lesion. All parameters were strongly related, in particular an inverse relationship emerged between median values of K_app and D_app/D_mono/ADC in both patient groups, while D_app showed positive correlations with D_mono and ADC. From the analysis at the voxel level, significant inverse associations were found between K_app and D_mono within the lesions, while a weak or moderate association emerged between K_app and ADC or D_app.ConclusionsA significant association between the apparent diffusional kurtosis K_app and the tissue diffusion coefficient D_mono emerged for both brain and HN tumors at 3 T, suggesting that both variables may consistently reflect deeper insight into the microstructural characteristics of tumors.     

BOLD signal compartmentalization based on the apparent diffusion coefficient

Functional MRI (fMRI) can detect blood oxygenation level dependent (BOLD) hemodynamic responses secondary to neuronal activity. The most commonly used method for detecting fMRI signals is the gradient-echo echo-planar imaging (EPI) technique because of its sensitivity and speed. However, it is generally believed that a significant portion of these signals arises from large veins, with additional contribution from the capillaries and parenchyma. Early experiments using diffusion-weighted gradient-echo EPI have suggested that intra-voxel incoherent motion (IVIM) weighting inherent in the sequence can selectively attenuate contributions from different vessels based on the differences in the mobility of the blood within them. In the present study, we used similar approach to characterize the apparent diffusion coefficient (ADC) distribution within the activated areas of BOLD contrast. It is shown that the voxel values of the ADCs obtained from this technique can infer various vascular contributions to the BOLD signal.     

Apparent diffusion coefficient of line scan diffusion image in normal prostate and prostate cancer—comparison with single-shot echo planner image

Purpose

This retrospective study was designed to evaluate the apparent diffusion coefficient (ADC) of line scan diffusion images (LSDI) in normal prostate and prostate cancer. Single-shot echo planner images (SS-EPI) were used for comparison.

Materials and Methods

Twenty prostate tumors were examined by conventional MRI in 14 patients prior to radical prostatectomy. All patients were examined with a 1.5-T MR imager (Signa CV/i ver. 9.1 GE Medical System Milwaukee, WI, USA). Diffusion-weighted MR imaging (DWI) using LSDI was performed with a pelvic phased-array coil, with b values of 5 and 800 s/mm². DWI using SS-EPI was performed with a body coil, with b values of 0 and 800 s/mm². The ADCs of each sequence for 14 normal prostate and 20 prostate cancers were histopathologically assessed. Signal-to-noise ratio (SNR) on DWI was estimated and compared for each sequence.

Results

The mean ADCs (±S.D.) of normal peripheral zones (PZ), transition zones (TZ) and cancer (in 10⁻³ mm²/s) that used LSDI were 1.42±0.12, 1.23±0.10 and 0.79±0.19, respectively. Those that used SS-EPI were 1.76±0.26, 1.38±0.20 and 1.05±0.27, respectively. Using unpaired t test (P<.05), we found a significant difference in each sequence between normal tissue (both PZ and TZ) and the cancer. Paired t test (P<.05) also registered a significant difference between LSDI and SS-EPI. Mean SNR for DWI using LSDI was 16.49±5.03, while the DWI using SS-EPI was 18.85±9.26. The difference between the SNR of each sequence was not statistically significant by paired t test.

Conclusion

We found that ADCs using LSDI and SS-EPI showed similar tendencies in the same patients. However, in all regions, LSDI ADCs had smaller standard deviations than SS-EPI ADCs.