Diffusion weighted imaging of liver lesions suspect for metastases: Apparent diffusion coefficient (ADC) values and lesion contrast are independent from Gd-EOB-DTPA administration

Evaluation of apparent diffuse coefficient (ADC) with regards to reproducibility and diagnostic accuracy as well as possible significance of pre - and post - contrast acquisition and employment of different b values

PURPOSE

Ongoing efforts are focusing on optimizing diffusion-weighted imaging (DWI) as an essential part of breast MRI protocol. Our study aimed to evaluate the effect of contrast media (CM) on the apparent diffusion coefficients (ADC) acquired following current recommendations.

PATIENT AND METHODS

Patients who underwent 3 T breast MRI with a histologically verified suspicious lesion were included in this IRB-approved, single-center, cross-sectional retrospective study. Breast MRI protocol included a DWI sequence with multiple b-values, which was acquired before and after CM administration. ADC maps were calculated by in-line monoexponential fitting with b-values 0 /800 and 50/800. Two independent readers (R1, R2) reviewed the images in separate sessions for b values 0/800 and 50/800, pre- and post-CM. Bland Altmann plots as well as intraclass correlation coefficients (ICCs) for inter-reader agreement, different b-values, and pre- and post-CM were calculated. Diagnostic accuracy was evaluated and compared by calculating the area under the receiver operating characteristics curve (AUC).

RESULTS

91 lesions in 89 patients were examined (mean age 50.7 years, standard deviation 13.9). ADC values were significantly (P<0.05) lower post-CM (mean ranging from 1.28 x10-3 mm2/s to 1.30 x10-3 mm2/s) compared to pre-CM (mean ranging from 1.32 x10-3 mm2/s to 1.37 x10-3 mm2/s) for both b-values combinations (0/800 and 50/800 s/mm2). We found an almost perfect inter-reader agreement pre-/post-CM with b values 0/800 and 50/800 (ICC ranging from 0.853 to 0.939). Bland Altman plot demonstrated no systematic difference between readers. ROC analysis revealed good diagnostic performance without significant differences (P>0.05) between b values 0/800 and 50/800 s/mm2 as well as pre- and post-CM with areas under the ROC curve between 0.834 and 0.877.

CONCLUSION

ADC values are slightly lower when acquiring b values 0/800 and post-CM. This effect does not reduce the diagnostic performance but may be relevant in case of definite cut-offs in medical decision making.

[Usefulness of Breath-hold DWI Focused on the Hepatic Dome in EOB-MRI]

PURPOSE

Respiratory-triggered-diffusion-weighted imaging (R-DWI) of the liver often results in poor image quality under the diaphragmatic dome on the cephalic side of the liver (hepatic dome) secondary to magnetic field inhomogeneity in liver magnetic resonance imaging (MRI). Hence, the usefulness of additional breath-hold-DWI (B-DWI) focusing on the hepatic dome was investigated.

METHODS

A total of 22 patients (14 men and 8 women; mean age 69.0±11.7 years) who underwent ethoxybenzyl (EOB)-MRI at our hospital between July and August, 2022 using a 3.0 T MRI system were included. One radiologist and three radiology technologists visually assessed the visibility of R-DWI and B-DWI in the hepatic dome on a 4-point scale (1 to 4). Additionally, the apparent diffusion coefficient (ADC) values of the hepatic parenchyma on each DWI were compared.

RESULTS

B-DWI improved visibility in the hepatic dome compared to R-DWI (2.67±0.71 vs. 3.25±0.43, p<0.05). No significant difference was found in the ADC values for each DWI.

CONCLUSION

B-DWI has excellent visibility in the hepatic dome and is expected to complement R-DWI. Therefore, B-DWI is very useful as an additional imaging in EOB-MRI.

Advanced Magnetic Resonance Imaging Modalities for Breast Cancer Diagnosis: An Overview of Recent Findings and Perspectives

Breast cancer is the most prevalent cancer among women and the leading cause of death. Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are advanced magnetic resonance imaging (MRI) procedures that are widely used in the diagnostic and treatment evaluation of breast cancer. This review article describes the characteristics of new MRI methods and reviews recent findings on breast cancer diagnosis. This review study was performed on the literature sourced from scientific citation websites such as Google Scholar, PubMed, and Web of Science until July 2021. All relevant works published on the mentioned scientific citation websites were investigated. Because of the propensity of malignancies to limit diffusion, DWI can improve MRI diagnostic specificity. Diffusion tensor imaging gives additional information about diffusion directionality and anisotropy over traditional DWI. Recent findings showed that DWI and DTI and their characteristics may facilitate earlier and more accurate diagnosis, followed by better treatment. Overall, with the development of instruments and novel MRI modalities, it may be possible to diagnose breast cancer more effectively in the early stages.

Diffusion-weighted imaging of the breast-a consensus and mission statement from the EUSOBI International Breast Diffusion-Weighted Imaging working group

The European Society of Breast Radiology (EUSOBI) established an International Breast DWI working group. The working group consists of clinical breast MRI experts, MRI physicists, and representatives from large vendors of MRI equipment, invited based upon proven expertise in breast MRI and/or in particular breast DWI, representing 25 sites from 16 countries. The aims of the working group are (a) to promote the use of breast DWI into clinical practice by issuing consensus statements and initiate collaborative research where appropriate; (b) to define necessary standards and provide practical guidance for clinical application of breast DWI; (c) to develop a standardized and translatable multisite multivendor quality assurance protocol, especially for multisite research studies; (d) to find consensus on optimal methods for image processing/analysis, visualization, and interpretation; and (e) to work collaboratively with system vendors to improve breast DWI sequences. First consensus recommendations, presented in this paper, include acquisition parameters for standard breast DWI sequences including specifications of b values, fat saturation, spatial resolution, and repetition and echo times. To describe lesions in an objective way, levels of diffusion restriction/hindrance in the breast have been defined based on the published literature on breast DWI. The use of a small ROI placed on the darkest part of the lesion on the ADC map, avoiding necrotic, noisy or non-enhancing lesion voxels is currently recommended. The working group emphasizes the need for standardization and quality assurance before ADC thresholds are applied. The working group encourages further research in advanced diffusion techniques and tailored DWI strategies for specific indications.

Key Points

• The working group considers breast DWI an essential part of a multiparametric breast MRI protocol and encourages its use.

• Basic requirements for routine clinical application of breast DWI are provided, including recommendations on b values, fat saturation, spatial resolution, and other sequence parameters.

• Diffusion levels in breast lesions are defined based on meta-analysis data and methods to obtain a reliable ADC value are detailed.

Conspicuity of Malignant Liver Tumors on Diffusion-Weighted Imaging With Short tau Inversion Recovery After Gadolinium Ethoxybenzyl Diethylenetriaminepentaacetic Acid Administration

BACKGROUND

Diffusion-weighted imaging (DWI) has been used for the detection and characterization of liver tumors because it has excellent contrast resolution. DWI using short tau inversion recovery (STIR) can improve tumor-to-liver contrast after gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) administration that shortens the T₁ relaxation of liver parenchyma.

PURPOSE

To quantitatively and qualitatively compare the conspicuity of malignant liver tumors on DWI after Gd-EOB-DTPA administration between STIR and chemical shift selective (CHESS) sequences.

STUDY TYPE

Single-institution retrospective study.

SUBJECTS

Fifty-seven patients with histologically confirmed malignant liver tumors were evaluated.

FIELD STRENGTH/SEQUENCE

Low b-value DWIs with STIR and CHESS sequences 18-20 minutes after Gd-EOB-DTPA administration were acquired at 1.5T.

ASSESSMENT

Tumor contrast-to-noise ratio (CNR) and visual grade of tumor conspicuity on DWI between STIR and CHESS sequences were compared.

STATISTICAL TESTS

Paired Student's t-test and the Wilcoxon signed rank-test were applied. P < 0.05 was considered statistically significant.

RESULTS

The mean tumor CNR and visual grade of tumor conspicuity on DWI were significantly higher for STIR than for CHESS (both P < 0.001). Regardless of the presence of chronic liver disease, the mean CNR (normal liver 33.5 ± 19.8 vs. 15.7 ± 12.2, P < 0.001; chronic liver disease 19.6 ± 11.0 vs. 9.2 ± 7.8, P < 0.001) and the visual conspicuity grade (normal liver 3.36 ± 0.64 vs. 2.56 ± 0.77, P < 0.001; chronic liver disease 2.94 ± 0.80 vs. 2.25 ± 0.84, P = 0.001) were significantly higher for STIR than for CHESS. Mean CNR and the visual conspicuity grade were also significantly higher for STIR than for CHESS in patients with hepatocellular carcinomas (CNR 18.1 ± 10.5 vs. 8.8 ± 7.2, P < 0.001; visual grade 2.88 ± 0.83 vs. 2.22 ± 0.87, P = 0.001) or metastases (CNR 35.0 ± 19.3 vs. 16.2 ± 13.1, P < 0.001; visual grade 3.45 ± 0.51 vs. 2.59 ± 0.73, P < 0.001).

DATA CONCLUSION

DWI using STIR may be more helpful for depicting malignant liver tumors after Gd-EOB-DTPA administration compared with DWI using CHESS.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:565-573.

Standard-b-Value Versus Low-b-Value Diffusion-Weighted Imaging in Hepatic Lesion Discrimination: A Meta-analysis

OBJECTIVE

We sought to determine the comparative diagnostic performance of standard-b-value (500-1000s/mm) versus low-b-value (≤500 s/mm) diffusion-weighted imaging (DWI) in the discrimination of hepatic lesions.

METHODS

A total of 1775 hepatic malignant lesions and 1120 benign hepatic lesions from 21 studies were included.

RESULTS

(1) The global sensitivity was 0.86 (95% confidence interval [CI], 0.847-0.879), the specificity was 0.82 (95% CI, 0.797-0.842), the positive likelihood ratio (PLR) was 6.234 (95% CI, 4.260-9.123), the negative likelihood ratio (NLR) was 0.175 (95% CI, 0.135-0.227), and diagnostic odds ratio (DOR) was 42.836 (95% CI, 24.134-76.031). The area under the curve (AUC) and Q* index were 0.93 and 0.87. Publication bias was not present (P > 0.05). (2)The sensitivity of a subgroup meta-analysis of standard-b-value DWI was 0.858 (95% CI, 0.835-0.880), the specificity was 0.836 (95% CI, 0.807-0.863), the PLR was 6.527 (95% CI, 3.857-11.046), the NLR was 0.168 (95% CI, 0.123-0.239), and the DOR was 49.716 (95% CI, 22.897-107.98). The AUC and Q* index were 0.941 and 0.88. (3)The sensitivity of a subgroup meta-analysis of low-b-value DWI was 0.87 (95% CI, 0.84-0.89), the specificity was 0.80 (95% CI, 0.76-0.83), the PLR was 6.22 (95% CI, 3.29-11.76), the NLR was 0.19 (95% CI, 0.12-0.29), and the DOR was 37.14 (95% CI, 14.80-93.18). The AUC and Q* index were 0.922 and 0.86.

CONCLUSIONS

Hepatic DWI is useful in differentiating between malignant and benign hepatic lesions. Standard-b-value DWI displayed an overall superior diagnostic accuracy over low-b-value DWI. Further trials needed to determine whether increasing b values beyond 1000 s/mm affects the diagnostic accuracy of hepatic lesion discrimination.

Gd-EOB-DTPA-Enhanced MR Imaging of the Liver: The Effect on T2 Relaxation Times and Apparent Diffusion Coefficient (ADC)

Background

To investigate the effect of gadoxetic acid disodium (Gd-EOB-DTPA) on T2 relaxation times and apparent diffusion coefficient (ADC) values of the liver and focal liver lesions on a 1.5-T system.

Material/Methods

Magnetic resonance (MR) studies of 50 patients with 35 liver lesions were retrospectively analyzed. All examinations were performed at 1.5T and included T2-weighted turbo spin-echo (TSE) and diffusion-weighted (DW) images acquired before and after intravenous administration of Gd-EOB-DTPA. To assess the effect of this hepatobiliary contrast agent on T2-weighted TSE images and DW images T2 relaxation times and ADC values of the liver and FLLs were calculated and compared pre- and post-injection.

Results

The mean T2 relaxation times of the liver and focal hepatic lesions were lower on enhanced than on unenhanced T2-weighted TSE images (decrease of 2.7% and 3.6% respectively), although these differences were not statistically significant. The mean ADC values of the liver showed statistically significant decrease (of 4.6%) on contrast-enhanced DW images, compared to unenhanced images (P>0.05). The mean ADC value of liver lesions was lower on enhanced than on unenhanced DW images, but this difference (of 2.9%) did not reach statistical significance.

Conclusions

The mean T2 relaxation times of the liver and focal liver lesions as well as the mean ADC values of liver lesions were not significantly different before and after administration of Gd-EOB-DTPA. Therefore, acquisition of T2-weighted and DW images between the dynamic contrast-enhanced examination and hepatobiliary phase is feasible and time-saving.

Detection and classification of different liver lesions: comparison of Gd-EOB-DTPA-enhanced MRI versus multiphasic spiral CT in a clinical single centre investigation

OBJECTIVE

To compare the diagnostic efficacy of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) vs. multidetector computed tomography (MDCT) for the detection and classification of focal liver lesions, differentiated also for lesion entity and size; a separate analysis of pre- and postcontrast images as well as T2-weighted MRI sequences of focal and exclusively solid lesions was integrated.

METHODS

Twenty-nine patients with 130 focal liver lesions underwent MDCT (64-detector-row; contrast medium iopromide; native, arterial, portalvenous, venous phase) and MRI (1.5-T; dynamic and tissue-specific phase 20 min after application of Gd-EOB-DTPA). Hepatic lesions were verified against a standard of reference (SOR). CT and MR images were independently analysed by four blinded radiologists on an ordinal 6-point-scale, determining lesion classification and diagnostic confidence.

RESULTS

Among 130 lesions, 68 were classified as malignant and 62 as benign by SOR. The detection of malignant and benign lesions differed significantly between combined and postcontrast MRI vs. MDCT; overall detection rate was 91.5% for combined MRI and 80.4% for combined MDCT (p<0.05). Considering all four readers together, combined MDCT achieved sensitivity of 66.2%, specificity of 79.0%, and diagnostic accuracy of 72.3%; combined MRI reached superior diagnostic efficacy: sensitivity 86.8%, specificity 94.4%, accuracy 90.4% (p<0.05). Differentiated for lesion size, in particular lesions <20mm revealed diagnostic benefit by MRI. Postcontrast MRI also achieved higher overall sensitivity, specificity, and accuracy compared to postcontrast MDCT for focal and exclusively solid liver lesions (p<0.05).

CONCLUSION

Combined and postcontrast Gd-EOB-DTPA-enhanced MRI provided significantly higher overall detection rate and diagnostic accuracy, including low inter-observer variability, compared to MDCT in a single centre study.

Using Gd-EOB-DTPA-enhanced 3-T MRI for the differentiation of infiltrative hepatocellular carcinoma and focal confluent fibrosis in liver cirrhosis

PURPOSE

The purpose of the study was to determine significant imaging features to differentiate between infiltrative hepatocellular carcinoma (HCC) and confluent fibrosis (CF) in liver cirrhosis using Gd-EOB-DTPA-enhanced 3-T magnetic resonance imaging.

MATERIAL AND METHODS

Nineteen infiltrative HCCs and eight CFs were included. We evaluated the difference in imaging findings and apparent diffusion coefficient (ADC) between the two entities. We compared T2-weighted image (WI) and hepatobiliary phase (HBP) in terms of the clarity of the lesion outer margin.

RESULTS

Seventeen infiltrative HCCs showed lobulated margin, while focal CFs showed either straight (n=3) or irregular margins (n=5) (P=.001). All infiltrative HCCs had intact or bulging contours, and all focal CFs showed capsular retraction (P=.001). Fourteen infiltrative HCCs and two focal CFs showed arterial enhancement (P=.035). The ADC of infiltrative HCCs was significantly lower than that of CFs (P=.001). Satellite nodules were noted in 10 infiltrative HCCs. In terms of outer margin clarity, infiltrative HCCs showed a more distinct margin on HBP than on T2-WI (P=.005), while these two sequences were not significantly different in focal CFs (P=1.000).

CONCLUSION

HBP improved the imaging characteristics of infiltrative HCC, allowing it to be distinguished from focal CF. Infiltrative HCC showed lower ADC values than focal CF. Lobular configuration, contour bulging, enhancement pattern, associated satellite nodules and portal vein thrombosis were still found to be highly suggestive MR findings for infiltrative HCC.

The effect of gadolinium chelate contrast agent on diffusion-weighted imaging of pancreatic ductal adenocarcinoma

BACKGROUND

There are only two studies that discuss the effect of a gadolinium chelate contrast agent on pancreatic diffusion-weighted imaging (DWI). However, both studies only included normal pancreas and/or pancreas with pancreatitis and did not include pancreatic ductal adenocarcinoma (PDA).

PURPOSE

To investigate the effect of gadolinium chelate contrast agent on DWI of PDA.

MATERIAL AND METHODS

Twenty-two patients (13 men, 9 women; mean age 62 years) with histopathologically proven PDA were included in this study. DWI was acquired before and after administration of gadopentetate dimeglumine (Magnevist) with two b-values: 0 and 1000 s/mm(2). The signal intensity (SI), signal-to-noise ratio (SNR), and the apparent diffusion coefficient (ADC) of the lesion were recorded for comparison.

RESULTS

The mean time interval between the initiation of contrast administration and the start of the postcontrast DWI series was 393 s (range, 350-510 s). The SIs and SNRs of lesions of b1000 and b0 images of enhanced images were significantly higher than non-enhanced images (P < 0.001, P < 0.001 for b1000 s/mm(2); P = 0.001, P = 0.001 for b0 s/mm(2)). The ADC of all PDAs revealed no statistically significant difference between non-enhanced and enhanced images (P = 0.709). There was also no significant difference between non-enhanced and enhanced images in subgroups based on grades of differentiation and locations of lesion.

CONCLUSION

With increasing SI and SNR of PDA, intravenous contrast administration does not result in a significant difference in quantitative ADC measurements when comparing precontrast to postcontrast DWI when acquired approximately 6-7 min after administration.