Prospective comparison of diffusion-weighted MRI and dynamic Gd-EOB-DTPA-enhanced MRI for detection and staging of hepatic fibrosis in primary sclerosing cholangitis

PURPOSE

To assess the diagnostic value of multiparametric magnetic resonance imaging (MRI) including dynamic Gd-EOB-DTPA-enhanced (DCE) and diffusion-weighted (DW) imaging for diagnosis and staging of hepatic fibrosis in primary sclerosing cholangitis (PSC) using transient elastography as a standard reference.

MATERIAL AND METHODS

Multiparametric MRI was prospectively performed on a 3.0-Tesla scanner in 47 patients (age 43.9±14.3 years). Transient elastography derived liver stiffness measurements (LSM), DCE-MRI derived parameters (hepatocellular uptake rate (Ki), arterial (Fa), portal venous (Fv) and total (Ft) blood flow, mean transit time (MTT), and extracellular volume (Ve)) and the apparent diffusion coefficient (ADC) were calculated. Correlation and univariate analysis of variance with post hoc pairwise comparison were applied to test for differences between LSM derived fibrosis stages (F0/F1, F2/3, F4). ROC curve analysis was used as a performance measure.

RESULTS

Both ADC and Ki correlated significantly with LSM (r= -0.614; p<0.001 and r= -0.368; p=0.01). The ADC significantly discriminated fibrosis stages F0/1 from F2/3 and F4 (p<0.001). Discrimination of F0/1 from F2/3 and F4 reached a sensitivity/specificity of 0.917/0.821 and 0.8/0.929, respectively. Despite significant inter-subject effect for classification of fibrosis stages, post hoc pairwise comparison was not significant for Ki (p>0.096 for F0/1 from F2/3 and F4). LSM, ADC and Ki were significantly associated with serum-based liver functional tests, disease duration and spleen volume.

CONCLUSION

DW-MRI provides a higher diagnostic performance for detection of hepatic fibrosis and cirrhosis in PSC patients in comparison to Gd-EOB-DTPA-enhanced DCE-MRI.

KEY POINTS

• Both ADC and hepatocellular uptake rate (Ki) correlate significantly with liver stiffness (r= -0.614; p<0.001 and r= -0.368; p=0.01). • The DCE-imaging derived quantitative parameter hepatocellular uptake rate (Ki) fails to discriminate pairwise intergroup differences of hepatic fibrosis (p>0.09). • DWI is preferable to DCE-imaging for discrimination of fibrosis stages F0/1 to F2/3 (p<0.001) and F4 (p<0.001).

Comparison of contrast-enhanced modified T1-weighted 3D TSE black-blood and 3D MP-RAGE sequences for the detection of cerebral metastases and brain tumours

OBJECTIVES

To compare a modified T1-weighted 3D TSE black-blood sequence with sub-millimetre resolution (T1-mVISTA) with a magnetization-prepared rapid gradient echo (MP-RAGE) sequence for the diagnosis of cerebral malignomas.

METHODS

Forty-six patients with known or suspected intracranial tumours and 15 control patients were included in this retrospective study. All patients underwent T1-mVISTA (0.75-mm isotropic resolution, 4:43 min) and MP-RAGE (0.8-mm isotropic resolution, 4:46 minutes) at 3-Tesla in random order after application of contrast agent. Two experienced radiologists determined the number of lesions. Maximum diameter, diagnostic confidence (DC), visual assessment of contrast enhancement (VCE) and CNRlesion/parenchyma were assessed for each lesion.

RESULTS

Significantly more lesions were detected with T1-mVISTA compared to the MP-RAGE (61 vs. 36; p < 0.05). Further, DC and VCE was rated significantly higher in the T1-mVISTA (p < 0.05 and p < 0.001). Mean CNRlesion/parenchyma was twofold higher for T1-mVISTA (24.2 ± 17.5 vs. 12.7 ± 11.5, p < 0.001). The 25 lesions detected only in T1-mVISTA were significantly smaller than those detected in both sequences (4.3 ± 3.7 mm vs. 11.3 ± 10.7 mm; p < 0.01).

CONCLUSIONS

T1-mVISTA increases the contrast of lesions significantly compared to MP-RAGE and might therefore improve detection rates of small lesions in early stages of disease.

KEY POINTS

• T1-mVISTA leads to significantly higher contrast-to-noise ratios of cerebral malignomas. • T1-mVISTA detects significantly more metastatic lesions compared to 3D-MPRAGE. • Lesions detected only by T1-mVISTA are smaller than those detected in both sequences. • Diagnostic confidence is significantly higher for lesions detected by T1-mVISTA. • Application of T1-mVISTA might be of high relevance in early stages of disease.

Monitoring of gustatory stimulation of salivary glands by diffusion-weighted MR imaging: comparison of 1.5T and 3T

BACKGROUND AND PURPOSE

Our aim was to compare different field strengths monitoring physiologic changes due to oral stimulation of parotid glands by using diffusion-weighted (DW) echo-planar imaging (EPI).

MATERIALS AND METHODS

Twenty-seven healthy volunteers were examined with a DW-EPI sequence at 1.5T and 3T before and after oral stimulation with commercially available lemon juice. The b factors used were 0, 500, and 1000 s/mm(2). Apparent diffusion coefficient (ADC) maps were evaluated with a manually placed region of interest including the entire parotid gland. For comparison of results, a Student t test was used on the basis of the mean of the volunteer median values. To compare both field strengths, we calculated the Pearson correlation coefficient (r).

RESULTS

DW-EPI MR imaging visualized the parotid glands of all volunteers. With 1.5T, the mean ADC before stimulation was 1.12 x 10(-3) mm(2)/s +/- 0.08 x 10(-3) mm(2)/s. After stimulation with lemon juice, the ADC increased to 1.18 x 10(-3) mm(2)/s +/- 0.09 x 10(-3) mm(2)/s. For 3T, the ADC before stimulation was 1.14 x 10(-3) mm(2)/s +/- 0.04 x 10(-3) mm(2)/s, with an increase to 1.17 x 10(-3) mm(2)/s +/- 0.05 x 10(-3) mm(2)/s after stimulation. For both field strengths, the increase in ADC after stimulation was significant (P < .001). High correlations between both field strengths were found pre- and poststimulation (r = 0.955, and 0.936, respectively).

CONCLUSION

DW-EPI MR imaging allows monitoring of physiologic changes due to oral stimulation of parotid glands by using DW imaging with high correlation between 1.5T and 3T.

The use of a surgical sealant (CoSeal) in cardiac and vascular reconstructive surgery: an economic analysis

AIM

We designed a study to estimate the economic impact of CoSeal Surgical Sealant for the prevention of anastomotic bleeding in cardiac and vascular surgery. We also explored the potential economic value of CoSeal as a means of inhibiting the formation of pericardial tissue adhesions.

METHODS

A Delphi panel of 6 expert vascular and cardiac surgeons provided the assumptions and estimates needed to develop a decision analysis model to assess the impact of sealant on the costs associated with low- and high-risk forms of cardiac (valve replacement/reconstruction) and vascular (abdominal aortic aneurysm [AAA] repair, femoral bypass grafting) surgery. The primary outcome was incremental cost per patient.

RESULTS

For valve repair/replacement surgery, sealant was expected to confer cost-savings in high-risk but not low-risk procedures. Predicted cost savings for high-risk AAA repairs were substantial, but minimal in the overall AAA group. Cost-savings were predicted for sealant use in all femoral-popliteal ePTFE bypass grafts, but in high-risk femoral-femoral ePTFE bypass grafts only.

CONCLUSIONS

According to our decision analysis model, routine use of surgical sealant in select subgroups may confer considerable economic benefits to health service budgets. Future research should aim at testing this model in a real-world hospital setting. Assessment of the value of CoSeal in the prevention of postsurgical adhesions showed that expert surgeons see a need for effective prophylaxis. Further research into the clinical and economic benefit of this intervention is required.