Diffusion weighted MR imaging in patients with HCC and liver cirrhosis after administration of different gadolinium contrast agents: is it still reliable?

Apparent diffusion coefficient values of cryptorchid testes and malignant transformation of cryptorchidism (MTC) (seminoma) in postpubertal patients

OBJECTIVES

Diffusion-weighted imaging signal contrast can be quantified by apparent diffusion coefficient (ADC) maps, which reflect the diffusion properties of the examined tissue and are helpful for identifying pathology. To determine ADC values of cryptorchid testes in post-pubertal patients and assess performance for characterizing cryptorchid testes.

METHODS

The medical records from 35 patients with unilateral scrotal vacuity were retrospectively reviewed. Data were analyzed in three groups: Group A, normal testes (i.e. the contralateral testes of the patients with cryptorchidism or MTC); Group B, cryptorchid testes; and Group C, malignant transformation of cryptorchidism (MTC) (seminoma). DWI used b-values of 0 and 800 s/mm². Mean ADC values were compared using the independent samples t-test. The ability of ADC values was assessed using receiver operating characteristic curve analysis. The sensitivity, specificity, and accuracy were calculated.

RESULTS

Mean ADC values for normal testes, cryptorchid testes, and MTC were 1.18 ± 0.18×10^-3 mm²/s, 1.82 ± 0.40×10^-3 mm²/s, and 0.80 ± 0.06×10^-3 mm²/s, respectively. There were statistically significant differences in mean ADC values between normal testes and cryptorchid testes or MTC (p < 0.001). The cut-off ADC value for differentiating normal testes from cryptorchid testes was 1.47 × 10^-3 mm²/s. The sensitivity, specificity, and accuracy were 88%, 91%, and 90%, respectively. The cut-off ADC value for differentiating normal testes from MTC was 1.22 × 10^-3 mm²/s. The sensitivity, specificity, and accuracy were 100%, 31%, and 43%, respectively.

CONCLUSION

ADC values of cryptorchid testes may be used to inform clinical decision-making and also monitor testicular function in patients who retain undescended testicles or post-operatively.

ADVANCES IN KNOWLEDGE

Mean ADC values of cryptorchidism and MTC (seminoma) were used to reflect their pathological features.

Simultaneous multi-slice accelerated diffusion-weighted imaging with higher spatial resolution for patients with liver metastases from neuroendocrine tumours

AIM

To evaluate the imaging characteristics of simultaneous multi-slice (SMS) accelerated diffusion-weighted imaging (DWI) with decreased section thickness, with and without motion correction, in comparison to conventional DWI (cDWI) for the detection of lesions in patients with neuroendocrine tumour (NET) liver metastases.

MATERIALS AND METHODS

Fifteen patients with NET liver metastases underwent cDWI (section thickness [SL]=4 mm) and SMS-DWI (SL=2 mm). Non-linear motion-corrected (Moco)-SMS-DWI was generated in addition to the original series. Qualitative imaging characteristics (five-point Likert scale), the number of high signal lesions, and the detectability and delineation of lesions were evaluated and compared using the Friedman and the Dunn-Bonferroni tests. The test-retest variability (TRV) of the cDWI and SMS-DWI techniques was investigated among 11 healthy volunteers who underwent cDWI (SL=4 mm) and SMS-DWI (SL=4 mm) twice. The Friedman and the Dunn-Bonferroni post-hoc tests were used to compare the mean apparent diffusion coefficient (ADC) and the TRV in different liver regions between the three series.

RESULTS

Moco-SMS-DWI demonstrated significantly superior overall image quality (p<0.001) with significantly fewer artefacts (p=0.003) than cDWI. The number of lesions detected by cDWI, SMS-DWI, and Moco-SMS-DWI were 348, 504, and 523, respectively. The detectability and delineation of the lesions and the ADC values were significantly higher on the SMS-DWI and Moco-SMS-DWI images than on the cDWI images (all p<0.001). Moco-SMS-DWI showed significantly higher TRV than cDWI in regions near the liver edge (p=0.018).

CONCLUSIONS

SMS-DWI achieves higher spatial resolution than cDWI within the same acquisition time, detects more lesions, and provides better lesion delineation. By applying motion correction, the TRV of DWI could be enhanced in regions near the liver edge.

Intra-individual comparison of conventional and simultaneous multislice-accelerated diffusion-weighted imaging in upper abdominal solid organs: value of ADC normalization using the spleen as a reference organ

PURPOSE

To compare the apparent diffusion coefficient (ADC) value of conventional diffusion-weighted imaging (cDWI) to simultaneous multislice-accelerated DWI (sDWI) and to evaluate the possibility of ADC normalization using the spleen as a reference organ.

METHODS

We retrospectively evaluated 92 patients (68 men, 24 women; mean age 60.0 years) who underwent liver magnetic resonance imaging (MRI) including both cDWI and sDWI. sDWI was obtained with an acceleration factor of 2. ADC values were measured from the right liver lobe, left liver lobe, spleen, pancreas, right kidney, and left kidney. ADC values of the spleen were used for normalization. Paired sample t test, Pearson's correlation coefficient, and Bland-Altman method were used for statistical analysis.

RESULTS

ADC values of cDWI were significantly lower than sDWI in all six anatomic regions (p < 0.001). The mean difference in ADC value between cDWI and sDWI ranged from 0.048 to 0.125 × 10^-3 mm²/s. ADC values from cDWI and sDWI showed a moderate to very high positive correlation (p < 0.001). After ADC normalization using the spleen as a reference organ, there was no significant difference between normalized ADC of cDWI and sDWI in all 5 anatomic regions (p = 0.11 - 0.74).

CONCLUSIONS

Normalization of ADC using the spleen could be useful for comparing upper abdominal organs acquired with either cDWI or sDWI in longitudinal and follow-up studies.

Intravoxel Incoherent Motion Diffusion-weighted Imaging: Evaluation of the Differentiation of Solid Hepatic Lesions

PURPOSE

To evaluate whether intravoxel incoherent motion (IVIM)-related parameters could be used to differentiate malignant from benign focal liver lesions (FLLs) and to improve diagnostic efficiency.

METHODS

Seventy-four patients with 75 lesions, including 51 malignant FLLs and 24 benign FLLs, underwent liver 3.0-T magnetic resonance imaging for routine examination sequences. IVIM diffusion-weighted imaging (DWI) with 11 b values (0-800s/mm²) was also acquired concurrently. Apparent diffusion coefficient (ADC_total) and IVIM-derived parameters, such as the pure diffusion coefficient (D), the pseudodiffusion coefficient (D^⁎), and the perfusion fraction (f), were calculated and compared between the two groups. A receiver operating characteristic curve analysis was performed to assess their diagnostic value.

RESULTS

ADC_total, D, and f were significantly lower in the malignant group than in the benign group, whereas D^⁎ did not show a statistical difference. D had a larger area under the curve value (0.968) and higher sensitivity (92.30%) for differentiation.

CONCLUSION

IVIM is a useful method to differentiate malignant and benign FLLs. The D value showed higher efficacy to detect hepatic solid lesions.

Evaluation of Free Breathing Versus Breath Hold Diffusion Weighted Imaging in Terms Apparent Diffusion Coefficient (ADC) and Signal-to-Noise Ratio (SNR) Values for Solid Abdominal Organs

Background

Our aim was to compare the apparent diffusion coefficient (ADC) values of normal abdominal parenchymal organs and signal-to-noise ratio (SNR) measurements in the same patients with breath hold (BH) and free breathing (FB) diffusion weighted imaging (DWI).

Material/Methods

Forty-eight patients underwent both BH and FB DWI. Spherical region of interest (ROI) was placed on the right hepatic lobe, spleen, pancreas, and renal cortices. ADC values were calculated for each organ on each sequence using an automated software. Image noise, defined as the standard deviation (SD) of the signal intensities in the most artifact-free area of the image background was measured by placing the largest possible ROI on either the left or the right side of the body outside the object in the recorded field of view. SNR was calculated using the formula: SNR=signal intensity (SI)_(organ)/standard deviation (SD)_(noise).

Results

There were no statistically significant differences in ADC values of the abdominal organs between BH and FB DWI sequences (p>0.05). There were statistically significant differences between SNR values of organs on BH and FB DWIs. SNRs were found to be better on FB DWI than BH DWI (p<0.001).

Conclusions

Free breathing DWI technique reduces image noise and increases SNR for abdominal examinations. Free breathing technique is therefore preferable to BH DWI in the evaluation of abdominal organs by DWI.

Intra-Individual, Inter-Vendor Comparison of Diffusion-Weighted MR Imaging of Upper Abdominal Organs at 3.0 Tesla with an Emphasis on the Value of Normalization with the Spleen

OBJECTIVE

To compare the apparent diffusion coefficient (ADC) values of upper abdominal organs with 2 different 3.0 tesla MR systems and to investigate the usefulness of normalization using the spleen.

MATERIALS AND METHODS

Forty-one patients were enrolled in this prospective study, of which, 35 patients (M:F, 27:8; mean age ± standard deviation, 62.3 ± 12.3 years) were finally analyzed. In addition to the routine liver MR protocol, single-shot spin-echo echo-planar diffusion-weighted imaging using b values of 0, 50, 400, and 800 s/mm(2) in 2 different MR systems was performed. ADC values of the liver, spleen, pancreas, kidney and liver lesion (if present) were measured and analyzed. ADC values of the spleen were used for normalization. The Pearson correlation, Spearman correlation, paired sample t test, Wilcoxon signed rank test and Bland-Altman method were used for statistical analysis.

RESULTS

For all anatomical regions and liver lesions, both non-normalized and normalized ADC values from 2 different MR systems showed significant correlations (r = 0.5196-0.8488). Non-normalized ADC values of both MR systems differed significantly in all anatomical regions and liver lesions (p < 0.001). However, the normalized ADC of all anatomical regions and liver lesions did not differ significantly (p = 0.065-0.661), with significantly lower coefficient of variance than that of non-normalized ADC (p < 0.009).

CONCLUSION

Normalization of the abdominal ADC values using the spleen as a reference organ reduces differences between different MR systems, and could facilitate consistent use of ADC as an imaging biomarker for multi-center or longitudinal studies.

Surveillance and diagnostic algorithm for hepatocellular carcinoma proposed by the Liver Cancer Study Group of Japan: 2014 update

Surveillance and diagnostic algorithms for hepatocellular carcinoma (HCC) have already been described in guidelines published by the American Association for the Study of Liver Diseases (AASLD), the European Association for the Study of the Liver and the European Organisation for Research and Treatment of Cancer (EASL-EORTC), and the Japan Society of Hepatology (JSH), but the content of these algorithms differs slightly. The JSH algorithm mainly differs from the other two algorithms in that it is highly sophisticated and considers the functional imaging techniques of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MRI (EOB-MRI) and Sonazoid contrast-enhanced ultrasound (CEUS) to be very important diagnostic modalities. In contrast, the AASLD and EASL-EORTC algorithms are less advanced and suggest that a diagnosis be made based solely on hemodynamic findings using dynamic CT/MRI and biopsy findings. A consensus meeting regarding the JSH surveillance and diagnostic algorithm was held at the 50th Liver Cancer Study Group of Japan Congress, and a 2014 update of the algorithm was completed. The new algorithm reaffirms the very important role of EOB-MRI and Sonazoid CEUS in the surveillance and diagnosis of liver cancer and is more sophisticated than those currently used in the United States and Europe. This is now an optimized algorithm that can be used to diagnose early-stage to classical HCC easily and highly accurately.

Is 3-Tesla Gd-EOB-DTPA-enhanced MRI with diffusion-weighted imaging superior to 64-slice contrast-enhanced CT for the diagnosis of hepatocellular carcinoma?

Objectives

To compare 64-slice contrast-enhanced computed tomography (CT) with 3-Tesla magnetic resonance imaging (MRI) using Gd-EOB-DTPA for the diagnosis of hepatocellular carcinoma (HCC) and evaluate the utility of diffusion-weighted imaging (DWI) in this setting.

Methods

3-phase-liver-CT was performed in fifty patients (42 male, 8 female) with suspected or proven HCC. The patients were subjected to a 3-Tesla-MRI-examination with Gd-EOB-DTPA and diffusion weighted imaging (DWI) at b-values of 0, 50 and 400 s/mm². The apparent diffusion coefficient (ADC)-value was determined for each lesion detected in DWI. The histopathological report after resection or biopsy of a lesion served as the gold standard, and a surrogate of follow-up or complementary imaging techniques in combination with clinical and paraclinical parameters was used in unresected lesions. Diagnostic accuracy, sensitivity, specificity, and positive and negative predictive values were evaluated for each technique.

Results

MRI detected slightly more lesions that were considered suspicious for HCC per patient compared to CT (2.7 versus 2.3, respectively). ADC-measurements in HCC showed notably heterogeneous values with a median of 1.2±0.5×10⁻³ mm²/s (range from 0.07±0.1 to 3.0±0.1×10⁻³ mm²/s). MRI showed similar diagnostic accuracy, sensitivity, and positive and negative predictive values compared to CT (AUC 0.837, sensitivity 92%, PPV 80% and NPV 90% for MRI vs. AUC 0.798, sensitivity 85%, PPV 79% and NPV 82% for CT; not significant). Specificity was 75% for both techniques.

Conclusions

Our study did not show a statistically significant difference in detection in detection of HCC between MRI and CT. Gd-EOB-DTPA-enhanced MRI tended to detect more lesions per patient compared to contrast-enhanced CT; therefore, we would recommend this modality as the first-choice imaging method for the detection of HCC and therapeutic decisions. However, contrast-enhanced CT was not inferior in our study, so that it can be a useful image modality for follow-up examinations.

JSH Consensus-Based Clinical Practice Guidelines for the Management of Hepatocellular Carcinoma: 2014 Update by the Liver Cancer Study Group of Japan

The Clinical Practice Guidelines for the Management of Hepatocellular Carcinoma proposed by the Japan Society of Hepatology was updated in June 2014 at a consensus meeting of the Liver Cancer Study Group of Japan. Three important items have been updated: the surveillance and diagnostic algorithm, the treatment algorithm, and the definition of transarterial chemoembolization (TACE) failure/refractoriness. The most important update to the diagnostic algorithm is the inclusion of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging as a first line surveillance/diagnostic tool. Another significant update concerns removal of the term "lipiodol" from the definition of TACE failure/refractoriness.

Addition of diffusion-weighted imaging can improve diagnostic confidence in bowel MRI

AIM

To evaluate whether the addition of diffusion-weighted imaging (DWI) in bowel abdominal magnetic resonance imaging (MRI) can improve diagnostic confidence.

MATERIALS AND METHODS

One hundred and eleven consecutive patients with suspected or known inflammatory bowel disease (n = 59), tumour disease (n = 31), unspecific abdominal pain (n = 16), and suspected graft-versus-host disease (n = 5) underwent bowel MRI using a 1.5 T MRI machine. In addition to T2-weighted (T2W) and contrast-enhanced T1-weighted (CE-T1W) data, axial and coronal DWI sequences were collected (b = 50, 500, 1000). Diagnostic confidence for lesion detection with and without DWI was evaluated using a four-point Likert scale [1 = certainly no lesion(s), 2 = probably no lesion(s), 3 = probably lesion(s), 4 = certainly lesion(s)].

RESULTS

In 11 of 111 patients (10%), the diagnostic confidence was improved by DWI. In seven patients, readers changed their diagnosis from "probable" to "certain presence of lesions". In another four patients, lesions were diagnosed based on DWI, which were not delineated on CE-T1W and T2W imaging.

CONCLUSION

DWI of the bowel can provide additional information to the reader and, therefore, improve diagnostic confidence. Hence, additional DWI should be integrated into a standard bowel MRI protocol.

Whole body MRI: improved lesion detection and characterization with diffusion weighted techniques

Diffusion-weighted imaging (DWI) is an established functional imaging technique that interrogates the delicate balance of water movement at the cellular level. Technological advances enable this technique to be applied to whole-body MRI. Theory, b-value selection, common artifacts and target to background for optimized viewing will be reviewed for applications in the neck, chest, abdomen, and pelvis. Whole-body imaging with DWI allows novel applications of MRI to aid in evaluation of conditions such as multiple myeloma, lymphoma, and skeletal metastases, while the quantitative nature of this technique permits evaluation of response to therapy. Persisting signal at high b-values from restricted hypercellular tissue and viscous fluid also permits applications of DWI beyond oncologic imaging. DWI, when used in conjunction with routine imaging, can assist in detecting hemorrhagic degradation products, infection/abscess, and inflammation in colitis, while aiding with discrimination of free fluid and empyema, while limiting the need for intravenous contrast. DWI in conjunction with routine anatomic images provides a platform to improve lesion detection and characterization with findings rivaling other combined anatomic and functional imaging techniques, with the added benefit of no ionizing radiation.

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.

Effects of gadoxetic acid on quantitative diffusion-weighted imaging of the liver

PURPOSE

To prospectively evaluate the effect of gadoxetic acid (Gd-EOB-DTPA; Primovist, Bayer-Schering, Berlin, Germany) on quantitative diffusion-weighted imaging (DWI) using the Le Bihan IntraVoxel Incoherent Motion model and considering separately the following parameters: slow diffusion coefficient (D), fast diffusion coefficient (D*), perfusion fraction (PF), and apparent diffusion coefficient (ADC).

MATERIALS AND METHODS

Twenty-four consecutive patients were submitted to the same magnetic resonance (MR)-DWI acquisition before and after gadoxetic acid administration. Patients were divided into four groups according to the time at which the DW sequence was repeated, then 5, 10, 15, 20 minutes after contrast agent administration. A total of 48 manually drawn regions of interest (ROIs) of about 1200 pixels were placed in the middle right liver lobe. The mean and standard deviation (SD) were calculated in each group/patient for every DWI-related parameter. Analysis of variance was performed (threshold P = 0.05). Bonferroni and Games-Howell post-hoc tests were applied if significant differences were found among groups; otherwise, data were averaged together.

RESULTS

D, D*, PF, and ADC did not show any significant difference before and after contrast agent administration, at any time.

CONCLUSION

It is possible to perform DW acquisitions after gadoxetic acid administration without any significant variation of the values of DW-related parameters under consideration in this study.