Alexander Huppertz

Liver tumor characterization: Comparison between liver-specific gadoxetic acid disodium-enhanced MRI and biphasic CT - A multicenter trial

Objective: In our multi center trial we compared the potentials of biphasic contrast-enhanced computed tomography (CT) and a novel tissue-specific magnetic resonance imaging (MRI) contrast agent gadoxetic acid disodium in liver lesion characterization. Methods: A total of 176 patients with 252 liver lesions were analyzed. There were 104 malignant and 148 benign lesions. High-field strength (1.0 T or 1.5 T) MR systems with T1-and T2-weighted sequences were used with and without fat suppression. After gadoxetic acid disodium injection, dynamic imaging and hepatocyte phase MR imaging were performed. Biphasic with 150 mg I/kg of body weight (100-200 mL) spiral CT was also performed. Image reading consisted of on-site (by study investigators) and fully blinded off-site (by E.S.P; C.R; and A.S) evaluations. The classification (benign or malignant) and characterization (lesion type) outcomes of both techniques were assessed. All imaging results were verified against a standard of reference. Results: Both on-site and off-site evaluations demonstrated increases in the lesion classification accuracy with gadoxetic acid disodium-enhanced MRI when compared with spiral CT. This improvement was also shown for characterization. Gadoxetic acid disodium was well tolerated. Conclusions: Gadoxetic acid disodium offers a safe and diagnostically powerful tool for the evaluation of patients with focal liver lesions with a reliable assessment of lesion classification and characterization.

Areas suspicious for prostate cancer: MR-guided biopsy in patients with at least one transrectal US-guided biopsy with a negative finding--multiparametric MR imaging for detection and biopsy planning.

PURPOSE To prospectively investigate the incremental value of multiparametric magnetic resonance (MR) imaging compared with standard T2-weighted imaging for biopsy planning. MATERIALS AND METHODS The study was approved by the institutional review board; informed consent was obtained. Consecutive patients underwent T2-weighted imaging supplemented with multiparametric 1.5-T MR imaging, consisting of hydrogen 1 ((1)H) MR spectroscopy, diffusion-weighted (DW) imaging, and contrast material-enhanced MR imaging. Quantitative parameters were calculated: (choline plus creatine)-to-citrate ratio, apparent diffusion coefficient, and volume transfer constant and exchange rate constant. The prostate was divided into 20 standardized areas. Each area was classified as benign, inconclusive, or suspicious at T2-weighted imaging, followed by quantitative evaluation of all inconclusive and suspicious areas with multiparametric MR imaging. MR-guided biopsy was performed in lesions classified as suspicious for cancer with at least one of the techniques after transfer to three-dimensional T2-weighted images. Diagnostic parameters were calculated on a per-lesion and per-patient basis for all combinations of T2-weighted imaging with multiparametric MR imaging. RESULTS Fifty-four patients had a median of two prior transrectal ultrasonographic biopsies with negative findings. Each patient had a median of three suspicious lesions. Prostate cancer was demonstrated in 21 of 54 patients. Biopsy was performed in 178 lesions; 53 were positive for prostate cancer. Detection rates and test negative results, respectively, were as follows: T2-weighted imaging, 70% and 50%; T2-weighted imaging and (1)H MR spectroscopy, 81% and 32%; T2-weighted imaging and contrast-enhanced MR imaging, 83% and 29%; T2-weighted imaging and DW imaging, 85% and 30%; T2-weighted imaging, (1)H MR spectroscopy, and contrast-enhanced MR imaging, 91% and 13%; T2-weighted imaging, (1)H MR spectroscopy, and DW imaging, 94% and 15%; T2-weighted imaging, DW imaging, and contrast-enhanced MR imaging, 94% and 13%; T2-weighted imaging, (1)H MR spectroscopy, DW imaging, and contrast-enhanced MR imaging, 100% and 0%. CONCLUSION Only the combination of T2-weighted imaging with all three multiparametric techniques depicts all identifiable prostate cancers; a double combination with DW imaging and (1)H MR spectroscopy or contrast-enhanced MR imaging misses 6%, while reasonably reducing the number of areas needing biopsy.

Qualitative and Quantitative Evaluation of Hepatocellular Carcinoma and Cirrhotic Liver Enhancement Using Gd-EOB-DTPA

OBJECTIVE The objective of our study was to prospectively evaluate quantitatively and qualitatively the enhancement patterns of cirrhotic liver tissue and hepatocellular carcinoma (HCC) after administration of the hepatocyte-specific contrast agent gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) on dynamic MRI and to determine the time point of maximum liver-to-lesion contrast. SUBJECTS AND METHODS Twenty-five patients with HCC in liver cirrhosis underwent 1.5-T MRI. T2-weighted turbo spin-echo and T1-weighted 3D gradient-echo sequences before and between 15 seconds and 20 minutes after the injection of 10 mL of Gd-EOB-DTPA were performed. Signal-to-noise ratios (SNRs) of liver parenchyma and liver-to-lesion contrast-to-noise ratios (CNRs) were calculated and plotted over time. Enhancement patterns of HCC were characterized qualitatively by two radiologists. RESULTS The SNR of liver parenchyma increased significantly at 15 seconds and 60 seconds after contrast injection and remained stable thereafter. HCC showed positive CNR during the arterial phase and increasingly negative CNR during the further time course (p < 0.05). The maximum absolute CNR was found at 20 minutes after contrast injection. There was no correlation between the degree of enhancement at any time point and tumor grade. On qualitative evaluation, 16 HCCs showed arterial enhancement with early washout, and five showed arterial enhancement with late washout. In the remaining four HCCs, enhancement persisted until 20 minutes. Lesion conspicuity at 20 minutes after contrast injection was at least equal to or higher than it was on the remaining sequences in 19 of the 25 patients. CONCLUSION After Gd-EOB-DTPA injection, most HCCs showed typical arterial enhancement with early washout. Liver-to-lesion contrast was best at 20 minutes.

Consensus report of the 2nd International Forum for Liver MRI

Discussion at the 2nd Forum for Liver MRI: The International Primovist User Meeting on the use of the hepatocyte-specific contrast agent gadolinium-ethoxybenzyl-diethylene triamine penta-acetic acid (Gd-EOB-DTPA) is reported. Changes to the currently recommended Gd-EOB-DTPA imaging protocol were identified that can reduce the overall examination time. The potential benefits of 3-T MR imaging using Gd-EOB-DTPA have yet to be fully explored. Data show that Gd-EOB-DTPA-enhanced MRI allows identification of liver lesions and provides a differential diagnosis of hepatocellular nodules in the noncirrhotic and cirrhotic liver, based on vascularity, during the dynamic arterial, portal-venous and late phases, and during the hepatocytespecific phase. Current European, American and Japanese guidelines for the diagnosis of hepatocellular carcinoma need to take into account the recent rapid advances in liver imaging. Based on published clinical trials and the experience of the attendees in the use of Gd-EOB-DTPA in liver imaging, a new simplified, non-invasive diagnostic algorithm was proposed that would be applicable to both Eastern and Western clinical practice in the evaluation of hepatocarcinogenesis and hepatocellular carcinoma. Preliminary clinical experience suggests that Gd-EOB-DTPA may also provide an innovative and cost-effective one-stop approach for staging rectal cancer using wholebody imaging.

A Prospective Study for Comparison of MR and CT Imaging for Detection of Coronary Artery Stenosis

OBJECTIVES the purpose of the present study was to directly compare the diagnostic accuracy of magnetic resonance imaging (MRI) and multislice computed tomography (CT) for the detection of coronary artery stenosis. BACKGROUND both imaging modalities have emerged as potential noninvasive coronary imaging modalities; however, CT-unlike MRI-exposes patients to radiation and iodinated contrast agent. METHODS one hundred twenty consecutive patients with suspected or known coronary artery disease prospectively underwent 32-channel 3.0-T MRI and 64-slice CT before elective X-ray angiography. The diagnostic accuracy of the 2 modalities for detecting significant coronary stenosis (≥ 50% luminal diameter stenosis) in segments ≥ 1.5 mm diameter was compared with quantitative invasive coronary angiography as the reference standard. RESULTS in the patient-based analysis MRI and CT angiography showed similar diagnostic accuracy of 83% (95% confidence interval [CI]: 75 to 87) versus 87% (95% CI: 80 to 92), p = 0.38; sensitivity of 87% (95% CI: 76 to 93) versus 90% (95% CI: 80 to 95), p = 0.16; and specificity of 77% (95% CI: 63 to 87) versus 83% (95% CI: 70 to 91), p = 0.06, respectively. All cases of left main or 3-vessel disease were correctly diagnosed by MRI and CT angiography. In the patient-based analysis MRI and CT angiography were similar in their ability to identify patients who subsequently underwent revascularization: the area under the receiver-operator characteristic curve was 0.78 (95% CI: 0.69 to 0.87) for MRI and 0.82 (95% CI: 0.74 to 0.90) for CT angiography. CONCLUSIONS thirty-two channel 3.0-T MRI and 64-slice CT angiography similarly identify significant coronary stenosis in patients with suspected or known coronary artery disease scheduled for elective coronary angiography. However, CT angiography showed a favorable trend toward higher diagnostic performance.

First-pass whole-body magnetic resonance angiography (MRA) using the blood-pool contrast medium gadofosveset trisodium : Comparison to gadopentetate dimeglumine

Objectives:To evaluate gadofosveset trisodium for first-pass magnetic resonance angiography (MRA) in the setting of whole-body MRA (WB-MRA). Materials and Methods:Forty patients were examined using either 10 mL gadofosveset trisodium (n = 20) or 30 mL gadopentetate dimeglumine (n = 20), followed by arterial-phase imaging of 4 consecutive anatomic regions. Signal intensity was measured in 2 vessels per region. Relative contrast values (RC) were calculated. Arterial contrast, venous overlay, and image quality were rated by 2 radiologists. The Mann–Whitney U test was used to test for significance. Results:Compared with gadopentetate dimeglumine, gadofosveset trisodium enhanced imaging revealed higher RC values in 2 vessel regions, with the differences being significant in 3 of 4 vessel segments. Gadofosveset trisodium revealed lower RC values in 2 regions with significant differences in 2 segments. Qualitative evaluation revealed higher ratings for gadofosveset trisodium regarding all 3 criteria with significant differences in 2 regions. Conclusions:Gadofosveset trisodium serves well for first-pass imaging in WB-MRA.

Enhancement of liver parenchyma after injection of hepatocyte-specific MRI contrast media: a comparison of gadoxetic acid and gadobenate dimeglumine

To compare enhancement of liver parenchyma in MR imaging after injection of hepatocyte‐specific contrast media.

High Spatial Resolution T1-weighted Mr Imaging of Liver and Biliary Tract During Uptake Phase of a Hepatocyte-specific Contrast Medium

Objectives:The hypothesis for this prospective study was that T1-weighted respiratory triggered high spatial resolution images of the liver acquired during the uptake phase of a hepatobiliary contrast medium are technically feasible and provide significantly improved image quality compared with breath-hold images. Materials and Methods:An inversion recovery-prepared spoiled gradient echo sequence was developed that can be obtained with respiratory triggering. This sequence was acquired in 20 patients with a total of 41 focal liver lesions and compared with axial and coronal breath-hold spoiled gradient echo sequences. All 3 sequences were obtained in the hepatobiliary phase after intravenous injection of Gd-EOB-DTPA at a dosage of 0.025 mmol/kg of body weight. Quantitative evaluation measured the contour sharpness index of the common bile duct and calculated the relative contrast between liver lesions (common bile duct, respectively) and liver parenchyma. In the qualitative assessment, 2 readers independently scored the depiction of focal liver lesions and 3 segments of the biliary tract, the sharpness of hepatic vessels, and the level of artifacts. Statistical significance was assumed at P < 0.05. Results:The respiratory-triggered sequence was technically successful in all 20 patients, revealed significantly higher liver-lesion contrast, contour-sharpness index and scores for depiction of focal liver lesions, biliary tree, and sharpness of hepatic vessels compared with the respective breath-hold sequence. The relative contrast between the common bile duct and the liver parenchyma was significantly higher for the coronal breath-hold sequence compared with the respiratory-triggered sequence. No significant difference was found with respect to the level of artifacts. The 2 readers agreed in 77.9% of the qualitative assessments. Conclusions:T1-weighted respiratory triggered high spatial resolution images obtained in the hepatobiliary phase are technically feasible and significantly improve the image quality compared with breath-hold images.

Computed tomography for preoperative planning in minimal-invasive total hip arthroplasty: radiation exposure and cost analysis.

Computed tomography (CT) was used for preoperative planning of minimal-invasive total hip arthroplasty (THA). 92 patients (50 males, 42 females, mean age 59.5 years) with a mean body-mass-index (BMI) of 26.5 kg/m(2) underwent 64-slice CT to depict the pelvis, the knee and the ankle in three independent acquisitions using combined x-, y-, and z-axis tube current modulation. Arthroplasty planning was performed using 3D-Hip Plan(®) (Symbios, Switzerland) and patient radiation dose exposure was determined. The effects of BMI, gender, and contralateral THA on the effective dose were evaluated by an analysis-of-variance. A process-cost-analysis from the hospital perspective was done. All CT examinations were of sufficient image quality for 3D-THA planning. A mean effective dose of 4.0 mSv (SD 0.9 mSv) modeled by the BMI (p<0.0001) was calculated. The presence of a contralateral THA (9/92 patients; p=0.15) and the difference between males and females were not significant (p=0.08). Personnel involved were the radiologist (4 min), the surgeon (16 min), the radiographer (12 min), and administrative personnel (4 min). A CT operation time of 11 min and direct per-patient costs of 52.80 € were recorded. Preoperative CT for THA was associated with a slight and justifiable increase of radiation exposure in comparison to conventional radiographs and low per-patient costs.

Evaluation of the prostate imaging reporting and data system for the detection of prostate cancer by the results of targeted biopsy of the prostate.

PurposeThe purpose of this study was to evaluate the magnetic resonance prostate imaging reporting and data system (PI-RADS) for the detection of prostate cancer by the results of magnetic resonance imaging (MRI)–guided biopsy of the prostate as a reference standard. Patients and MethodsIn 55 patients who had undergone MRI-guided biopsy of the prostate, we retrospectively matched every biopsy core with the corresponding lesion in previously acquired endorectal multiparametric MRI including T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced MRI (DCE-MRI) at 1.5 T. Two readers blinded to the results of the biopsy evaluated each biopsied lesion according to the PI-RADS scoring system. The results of the targeted biopsy were used as a reference standard. Receiver operating characteristic analysis was performed for statistical analysis. ResultsA total of 113 lesions in the 55 patients were evaluated; 30 lesions were malignant. When evaluated according to the criteria of the PI-RADS scoring system, DCE-MRI revealed a lower area under the receiver operating characteristic curve (AUC) (0.76) compared with T2WI (0.88; P = 0.06) and DWI (0.93; P = 0.004). A sum score combining T2WI, DWI, and DCE-MRI yielded an AUC of 0.93, whereas a sum score combining only T2WI and DWI yielded an AUC of 0.95. In central gland lesions, T2WI showed a numerically higher AUC compared with DWI (0.98 and 0.95), whereas, in peripheral zone lesions, DWI was superior (AUC of 0.93 and 0.73; P = 0.04). An approach assigning a PI-RADS score for T2WI to central gland lesions and for DWI to peripheral zone lesions yielded an AUC of 0.96 and was numerically superior compared with any sequence alone and sum scores combining T2WI and DWI as well as T2WI, DWI, and DCE-MRI. ConclusionsThe PI-RADS scoring system shows a good diagnostic performance for the detection of prostate cancer when using a sum score. However, DCE-MRI does not seem to add significant value when evaluated according to the recommended criteria. Assigning a score for T2WI to central gland lesions and for DWI to peripheral zone lesions might be sufficient for stratification of patients for further diagnostic workup.