Meta‐analysis of diffusion‐weighted MRI in the differential diagnosis of lung lesions

Purpose:

To perform a meta‐analysis to evaluate the diagnostic performance of the diffusion‐weighted imaging (DWI) technique in differentiating malignant from benign lung lesions.

Materials and Methods:

Medical and scientific literature databases were searched for studies that assessed the diagnostic performance of DWI in patients suspected of lung cancer who underwent DWI and biopsy. Only studies in the English or Chinese language and published before September 2011 were considered for inclusion. Methodological quality was assessed by the Quality Assessment of Diagnostic Studies (QUADAS) instrument. Homogeneity was explored by the Chi‐square test and inconsistency index. Sensitivities (SEN), specificities, predictive values, diagnostic odds ratio (dOR), and areas under the receiver operator characteristic (ROC) curve were calculated. Potential threshold effect was investigated by using Spearman's correlation coefficient. Publication bias analysis was evaluated by Deeks' asymmetry test.

Results:

Of 33 eligible studies, 11 were included in the meta‐analysis, comprising 755 malignant and 294 benign lesions. Heterogeneity was found to have arisen primarily from threshold effect. The data points from the Deeks' funnel plot indicated the presence of publication bias. Methodological quality was moderate. The pooled weighted SEN with corresponding 95% confidence interval (CI) was 0.80 (95% CI: 0.76, 0.83), SPE was 0.93 (95% CI: 0.91, 0.95), positive likelihood ratio was 9.24 (95% CI: 3.58, 23.83), negative likelihood ratio was 0.24 (95% CI: 0.19, 0.29), and dOR was 46.14 (95% CI: 27.56, 77.26). The area under the ROC curve was 0.91 (95% CI: 0.89, 0.93).

Conclusion:

DWI is a noninvasive, nonradiative, and accurate technique for distinguishing between malignant and benign lung lesions. However, large‐scale randomized control trials are necessary to assess its clinical value and to establish standards of DWI for measurement, analysis, and cutoff values of diagnosis. J. Magn. Reson. Imaging 2013;37:1351–1358. © 2013 Wiley Periodicals, Inc.     

磁共振扩散加权成像动态监测中晚期宫颈癌放化疗疗效

目的：研究磁共振扩散加权成像(DWI)在中晚期宫颈癌放化疗疗效动态监测中的应用价值。方法前瞻性纳入42例病理证实为中晚期(Ⅱb 期以上)宫颈癌拟行放化疗的患者,于放化疗前、结束时及结束后1个月行盆腔 MR 扫描。3例患者于放化疗结束后立即行手术切除,其余39例患者放化疗结束后1个月复查,28例完全缓解(CR ),10例部分缓解(PR),1例病灶稳定(SD)。28例 CR 中,11例于放化疗结束时病灶即完全消失(即刻反应组),17例于放化疗结束后1个月病灶才完全消失(延迟反应组)。比较不同疗效组肿瘤最大径及表观扩散系数(ADC)的动态变化规律。结果CR 即刻反应组基线肿瘤最大径(3.6 cm±0.9 cm)显著小于 PR 组(5.3 cm±2.5 cm,P =0.046)和治疗结束时尚有病灶残留的患者(5.1 cm±1.9 cm,P =0.021)。治疗后1个月 CR 组病灶 ADC 值(1.43×10-3 mm2/ s±0.04)显著高于 PR 组(1.29×10-3 mm2/s±0.11,P <0.001)。不同疗效组患者肿瘤最大径及ADC 值有不同的变化规律,且放化疗结束时肿瘤 ADC 值与最大径二者变化率存在显著相关性(r=0.421,P =0.005)。结论肿瘤最大径对于中晚期宫颈癌放化疗疗效具有一定的预测价值,不同疗效组肿瘤最大径和 ADC 值具有不同的变化趋势,肿瘤 ADC 值可以作为疗效评估的辅助指标。     

Comparison of diffusion‐weighted MRI and 2‐[fluorine‐18]‐fluoro‐2‐deoxy‐D‐glucose positron emission tomography (FDG‐PET) for detecting primary colorectal cancer and regional lymph node metastases

Purpose

To examine the usefulness of diffusion‐weighted MRI (DW‐MRI) for the detection of both primary colorectal cancer and regional lymph node metastases, and compare its performance with 2‐[fluorine‐18]‐fluoro‐2‐deoxy‐D‐glucose positron emission tomography (FDG‐PET) in the same patients.

Materials and Methods

We studied 25 patients with known colorectal cancer. All underwent both DW‐MRI and FDG‐PET studies. The images were retrospectively assessed by visual inspection and the imaging findings were compared with histopathological findings on surgical specimens.

Results

Of the 27 primary colorectal lesions surgically excised in 25 patients, 23 (85.2%) were true‐positive on both DW‐MRI and FDG‐PET. Two cancers were false‐negative on DW‐MRI but true‐positive on FDG‐PET, and two were false‐negative on both DW‐MRI and FDG‐PET. With respect to the detectability of metastatic lymph nodes, DW‐MRI and FDG‐PET manifested a sensitivity of 80% (8/10) and 30.0% (3/10), a specificity of 76.9% (10/13) and 100% (13/13), and an accuracy of 78.3% (18/23) and 69.6% (16/23), respectively.

Conclusion

DW‐MRI is inferior to FDG‐PET for the detection of primary lesions, but superior for the detection of lymph node metastases. J. Magn. Reson. Imaging 2009;29:336–340. © 2009 Wiley‐Liss, Inc.     

Prostate cancer vs. post‐biopsy hemorrhage: Diagnosis with T2‐ and diffusion‐weighted imaging

Purpose:

To assess the value of quantitative T2 signal intensity (SI) and apparent diffusion coefficient (ADC) to differentiate prostate cancer from post‐biopsy hemorrhage, using prostatectomy as the reference.

Materials and Methods:

Forty‐five men with prostate cancer underwent prostate magnetic resonance imaging (MRI), including axial T1‐weighted imaging (T1WI), T2WI, and single‐shot echo‐planar image (SS EPI) diffusion‐weighted imaging. Two observers measured, in consensus, normalized T2 signal intensity (SI) (nT2, relative to muscle T2 SI), ADC, and normalized ADC (nADC, relative to urine ADC) on peripheral zone (PZ) tumors, benign PZ hemorrhage, and non‐hemorrhagic benign PZ. Tumor maps from prostatectomy were used as the reference. Mixed model analysis of variance was performed to compare parameters among the three tissue classes, and Pearson's correlation coefficient was utilized to assess correlation between parameters and tumor size and Gleason score. Receiver‐operating characteristic (ROC)‐curve analysis was used to determine the performance of nT2, ADC, and nADC for diagnosis of prostate cancer.

Results:

nT2, ADC, and nADC were significantly lower in tumor compared with hemorrhagic and non‐hemorrhagic benign PZ (P < 0.0001). There was a weak but significant correlation between ADC and Gleason score (r = ?0.30, P = 0.0119), and between ADC and tumor size (r = ?0.40, P = 0.0027), whereas there was no correlation between nT2 and Gleason score and tumor size. The areas under the curve to distinguish tumor from benign hemorrhagic and non‐hemorrhagic PZ were 0.97, 0.96, and 0.933 for nT2, ADC, and nADC, respectively.

Conclusion:

Quantitative T2 SI and ADC/nADC values may be used to reliably distinguish prostate cancer from post‐biopsy hemorrhage. J. Magn. Reson. Imaging 2010;31:1387–1394. © 2010 Wiley‐Liss, Inc.

     

Endometrial cancer: Utility of diffusion‐weighted magnetic resonance imaging with background body signal suppression at 3T

Purpose:

To prospectively assess the usefulness of diffusion‐weighted magnetic resonance imaging (MRI) with background body signal suppression (DWIBS) at 3T for the preoperative evaluation of endometrial cancer.

Materials and Methods:

Fifty‐two consecutive patients with biopsy‐proven endometrial cancer were examined with a 3T MR scanner, followed by a hysterectomy. MR examinations included T2‐weighted (T2WI), DWIBS, and dynamic contrast‐enhanced T1‐weighted imaging (DCEI). The apparent diffusion coefficient (ADC) was calculated in the tumor and normal myometrium. According to tumor grade, the mean ADC of the tumor was analyzed. The depth of myometrial invasion was independently assessed by two radiologists for three MRI datasets on a five‐point scale.

Results:

The mean ADC of the tumors was significantly lower than that of normal myometrium (P < 0.001). The mean ADC of grades 2 or 3 was significantly lower than grade 1 (P < 0.01). For predicting myometrial invasion, the specificity, accuracy, and area under the curve of combined T2WI and DWIBS in both readers were similar to DCEI (P > 0.05). Interreader agreement in all MRI datasets was excellent.

Conclusion:

DWIBS at 3T has potential for being an effective method for the preoperative evaluation of endometrial cancer. J. Magn. Reson. Imaging 2013;37:1151–1159. © 2012 Wiley Periodicals, Inc.     

Comparison of physiological triggering schemes for diffusion‐weighted magnetic resonance imaging in kidneys

Purpose:

To determine the potential benefit of combined respiratory‐cardiac triggering for diffusion‐weighted imaging (DWI) of kidneys compared to respiratory triggering alone (RT).

Materials and Methods:

Renal DWI was performed in 17 volunteers comparing RT, combined respiratory‐cardiac triggering (RCT), and combined respiratory‐cardiac triggering with slice position correction (RCTF). Data were analyzed in three ways: A1) Model‐free analysis of the signal stability over repeated measurements; A2) Analysis of the deviation from diffusion‐model fitting comparing the root mean squared error (RMSE), assessing within‐subject variabilities; and A3) Analysis of diffusion indices comparing between‐subject variabilities.

Results:

Combined respiratory‐cardiac triggering yielded lower signal fluctuations and more reliable diffusion parameter estimation than respiratory triggering alone in all three analysis methods: A1) The mean coefficient of variation (CV) for all subjects was 4.2 ± 1.1% and 4.3 ± 0.9% for RCT and RCTF, respectively, which was significantly lower compared to RT (5.3 ± 0.9%, P < 0.005); A2) RT yielded significantly higher RMSEs than RCT and RCTF; A3) The between‐subject variations of diffusion indices tended toward higher values for RT. The results were independent of perfusion contributions to the DWI data. No difference was determined between RCT and RCTF. Total acquisition time was only slightly prolonged for respiratory‐cardiac double‐triggering.

Conclusion:

Respiratory‐cardiac double‐triggering seems advantageous for renal DWI. J. Magn. Reson. Imaging 2010; 31:1144–1150. © 2010 Wiley‐Liss, Inc.     

Noninvasive mapping of regional response to segmental allergen challenge using magnetic resonance imaging and [F-18]fluorodeoxyglucose positron emission tomography.

Magnetic resonance (MR) and positron emission tomography (PET) imaging techniques were coregistered to demonstrate regional ventilation and inflammation in the lung for in vivo, noninvasive evaluation of regional lung function associated with allergic inflammation. Four Brown Norway rats were imaged pre- and post segmental allergen challenge using respiratory-gated He-3 magnetic resonance imaging (MRI) to visualize ventilation, T(1)-weighted proton MRI to depict inflammatory infiltrate, and [F-18]fluorodeoxyglucose-PET to detect regional glucose metabolism by inflammatory cells. Segmental allergen challenges were delivered and the pre- and postchallenge lung as well as the contralateral lung were compared. Coregistration of the imaging results demonstrated that regions of ventilation defects, inflammatory infiltrate, and increased glucose metabolism correlated well with the site of allergen challenge delivery and inflammatory cell recruitment, as confirmed by histology. This method demonstrates that fusion of functional and anatomic PET and MRI image data may be useful to elucidate the functional correlates of inflammatory processes in the lungs.     

Diffusion‐weighted echo‐planar magnetic resonance imaging for the assessment of tumor cellularity in patients with soft‐tissue sarcomas

Purpose

To investigate the eligibility of diffusion‐weighted imaging (DWI) for the evaluation of tumor cellularity in patients with soft‐tissue sarcomas.

Materials and Methods

Thirty consecutive patients with a total of 31 histologically‐proven soft‐tissue sarcomas prospectively underwent magnetic resonance imaging (MRI) including DWI with echo‐planar imaging (EPI) technique immediately before open biopsy (N = 1) or tumor resection (N = 30). Fourteen patients had no previous anticancer treatment, 16 had received neoadjuvant therapy. Tumor cellularity as determined from histological sections was compared with minimum apparent diffusion coefficient (ADC).

Results

Tumor cellularity correlated well with minimum ADC in a linear fashion, with a Pearson correlation coefficient of –0.88 (95% confidence interval [CI]: –0.75 to –0.96). This relationship was not influenced by prior anticancer treatment. There was only a tendency toward lower ADC in tumor with higher grading but no significant dependency (P = 0.08).

Conclusion

DWI has proven useful for the assessment of tumor cellularity in soft‐tissue sarcomas. In result, DWI may be used as a powerful noninvasive tool to monitor responses of cytotoxic treatment as reflected by changes in tumor cellularity. J. Magn. Reson. Imaging 2009. © 2009 Wiley‐Liss, Inc.     

Prostate cancer detection with 3 T MRI: Comparison of diffusion‐weighted imaging and dynamic contrast‐enhanced MRI in combination with T2‐weighted imaging

Purpose:

To evaluate the diagnostic ability of diffusion‐weighted imaging (DWI) and dynamic contrast‐enhanced imaging (DCEI) in combination with T2‐weighted imaging (T2WI) for the detection of prostate cancer using 3 T magnetic resonance imaging (MRI) with a phased‐array body coil.

Materials and Methods:

Fifty‐three patients with elevated serum levels of prostate‐specific antigen (PSA) were evaluated by T2WI, DWI, and DCEI prior to needle biopsy. The obtained data from T2WI alone (protocol A), a combination of T2WI and DWI (protocol B), a combination T2WI and DCEI (protocol C), and a combination of T2WI plus DWI and DCEI (protocol D) were subjected to receiver operating characteristic (ROC) curve analysis.

Results:

The sensitivity, specificity, accuracy, and area under the ROC curve (Az) for region‐based analysis were: 61%, 91%, 84%, and 0.8415, respectively, in protocol A; 76%, 94%, 90%, and 0.8931, respectively, in protocol B; 77%, 93%, 89%, and 0.8655, respectively, in protocol C; and 81%, 96%, 92%, and 0.8968, respectively in protocol D. ROC analysis revealed significant differences between protocols A and B (P = 0.0008) and between protocols A and D (P = 0.0004).

Conclusion:

In patients with elevated PSA levels the combination of T2WI, DWI, DCEI using 3 T MRI may be a reasonable approach for the detection of prostate cancer. J. Magn. Reson. Imaging 2010;31:625–631. © 2010 Wiley‐Liss, Inc.