Potential of Low Dose Leuco-Methylthioninium Bis(Hydromethanesulphonate) (LMTM) Monotherapy for Treatment of Mild Alzheimer's Disease: Cohort Analysis as Modified Primary Outcome in a Phase III Clinical Trial

Background:

LMTM is being developed as a treatment for AD based on inhibition of tau aggregation.

Objectives:

To examine the efficacy of LMTM as monotherapy in non-randomized cohort analyses as modified primary outcomes in an 18-month Phase III trial in mild AD.

Methods:

Mild AD patients (n = 800) were randomly assigned to 100 mg twice a day or 4 mg twice a day. Prior to unblinding, the Statistical Analysis Plan was revised to compare the 100 mg twice a day as monotherapy subgroup (n = 79) versus 4 mg twice a day as randomized (n = 396), and 4 mg twice a day as monotherapy (n = 76) versus 4 mg twice a day as add-on therapy (n = 297), with strong control of family-wise type I error.

Results:

The revised analyses were statistically significant at the required threshold of p < 0.025 in both comparisons for change in ADAS-cog, ADCS-ADL, MRI atrophy, and glucose uptake. The brain atrophy rate was initially typical of mild AD in both add-on and monotherapy groups, but after 9 months of treatment, the rate in monotherapy patients declined significantly to that reported for normal elderly controls. Differences in severity or diagnosis at baseline between monotherapy and add-on patients did not account for significant differences in favor of monotherapy.

Conclusions:

The results are consistent with earlier studies in supporting the hypothesis that LMTM might be effective as monotherapy and that 4 mg twice a day may serve as well as higher doses. A further suitably randomized trial is required to test this hypothesis.

Efficacy and safety of tau-aggregation inhibitor therapy in patients with mild or moderate Alzheimer's disease: a randomised, controlled, double-blind, parallel-arm, phase 3 trial

BACKGROUND

Leuco-methylthioninium bis(hydromethanesulfonate; LMTM), a stable reduced form of the methylthioninium moiety, acts as a selective inhibitor of tau protein aggregation both in vitro and in transgenic mouse models. Methylthioninium chloride has previously shown potential efficacy as monotherapy in patients with Alzheimer's disease. We aimed to determine whether LMTM was safe and effective in modifying disease progression in patients with mild to moderate Alzheimer's disease.

METHODS

We did a 15-month, randomised, controlled double-blind, parallel-group trial at 115 academic centres and private research clinics in 16 countries in Europe, North America, Asia, and Russia with patients younger than 90 years with mild to moderate Alzheimer's disease. Patients concomitantly using other medicines for Alzheimer's disease were permitted to be included because we considered it infeasible not to allow their inclusion; however, patients using medicines carrying warnings of methaemoglobinaemia were excluded because the oxidised form of methylthioninium in high doses has been shown to induce this condition. We randomly assigned participants (3:3:4) to 75 mg LMTM twice a day, 125 mg LMTM twice a day, or control (4 mg LMTM twice a day to maintain blinding with respect to urine or faecal discolouration) administered as oral tablets. We did the randomisation with an interactive web response system using 600 blocks of length ten, and stratified patients by severity of disease, global region, whether they were concomitantly using Alzheimer's disease-labelled medications, and site PET capability. Participants, their study partners (generally carers), and all assessors were masked to treatment assignment throughout the study. The coprimary outcomes were progression on the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) and the Alzheimer's Disease Co-operative Study-Activities of Daily Living Inventory (ADCS-ADL) scales from baseline assessed at week 65 in the modified intention-to-treat population. This trial is registered with Clinicaltrials.gov (NCT01689246) and the European Union Clinical Trials Registry (2012-002866-11).

FINDINGS

Between Jan 29, 2013, and June 26, 2014, we recruited and randomly assigned 891 participants to treatment (357 to control, 268 to 75 mg LMTM twice a day, and 266 to 125 mg LMTM twice a day). The prespecified primary analyses did not show any treatment benefit at either of the doses tested for the coprimary outcomes (change in ADAS-Cog score compared with control [n=354, 6·32, 95% CI 5·31-7·34]: 75 mg LMTM twice a day [n=257] -0·02, -1·60 to 1·56, p=0·9834, 125 mg LMTM twice a day [n=250] -0·43, -2·06 to 1·20, p=0·9323; change in ADCS-ADL score compared with control [-8·22, 95% CI -9·63 to -6·82]: 75 mg LMTM twice a day -0·93, -3·12 to 1·26, p=0·8659; 125 mg LMTM twice a day -0·34, -2·61 to 1·93, p=0·9479). Gastrointestinal and urinary effects were the most common adverse events with both high doses of LMTM, and the most common causes for discontinuation. Non-clinically significant dose-dependent reductions in haemoglobin concentrations were the most common laboratory abnormality. Amyloid-related imaging abnormalities were noted in less than 1% (8/885) of participants.

INTERPRETATION

The primary analysis for this study was negative, and the results do not suggest benefit of LMTM as an add-on treatment for patients with mild to moderate Alzheimer's disease. Findings from a recently completed 18-month trial of patients with mild Alzheimer's disease will be reported soon.

FUNDING

TauRx Therapeutics.

A multi-center, comparative, phase 3 study to determine the efficacy of gadofosveset-enhanced magnetic resonance angiography for evaluation of renal artery disease

PURPOSE

To determine prospectively the safety and efficacy of the blood-pool contrast agent gadofosveset trisodium in renal artery magnetic resonance angiography (MRA).

MATERIALS AND METHODS

Gadofosveset (0.03 mmol/kg) was administered to adult patients with known or suspected renal arterial disease in a multi-center phase 3 single dose study. The drug binds reversibly to albumin, prolonging the blood residence time, and allowing collection of images in the first-pass and steady-state phases. The combination of these images was compared to non-contrast MRA, using catheter X-ray angiography (XRA) as the standard of reference (SOR). All MRA images were collected at 1.5 T in one imaging session for direct comparison, and XRA within 30 days. Sensitivity, specificity, and accuracy for diagnosing significant disease (stenosis > or =50%) were calculated for MRA using three independent blinded readers. Patient safety was monitored for 72-96 h.

RESULTS

A total of 145 patients at 18 centers were enrolled and received gadofosveset; the 127 with complete efficacy data entered the primary efficacy analysis. Gadofosveset-enhanced MRA led to significant improvement (p<0.01) in sensitivity (+25%, +26%, +42%), specificity (+23%, +25%, +29%), and accuracy (+23%, +28%, +29%) over non-enhanced MRA for the three readers. The rate of uninterpretable examinations decreased from 30% to less than 2%. There were no serious adverse events, and the most common adverse events were nausea, pruritus, and headache (8% each). No significant trends in clinical chemistry parameters, nor significant changes in serum creatinine, were found following administration of gadofosveset.

CONCLUSION

In patients with known or suspected renal arterial disease, multi-phase gadofosveset-enhanced MRA significantly improves sensitivity, specificity, and accuracy versus non-enhanced MRA. Gadofosveset was safe and well tolerated in this patient population.

A Summary of Safety of Gadofosveset (MS-325) at 0.03 mmol/kg Body Weight Dose

OBJECTIVE

We sought to summarize the Phase II and Phase III clinical trials safety data for gadofosveset (Vasovist, MS-325), a new magnetic resonance angiography contrast agent.

MATERIALS AND METHODS

Subjects with known or suspected vascular disease were administered 0.03 mmol/kg gadofosveset (767 subjects) or placebo (49 subjects) in phase II and phase III studies. Overall safety data were pooled from 8 studies and included adverse event monitoring, clinical laboratory assays, vital signs, oxygen saturation, physical examination, and electrocardiography. The safety was monitored for 72 to 96 hours postinjection (PI), and safety comparison with x-ray angiography using iodinated contrast media also was performed in 318 subjects. In the phase II trial, 5 doses of gadofosveset and placebo were evaluated. In this study, 38 patients were administered placebo and 39 patients received 0.03 mmol/kg gadofosveset.

RESULTS

In pooled data, treatment related adverse events were reported by 176 (22.9%) patients receiving gadofosveset and by 16 (32.7%) patients receiving placebo. In phase II trial, treatment-related adverse events were reported by 13 of the 39 (33.3%) patients receiving gadofosveset and 9 of the 38 (23.7%) patients receiving placebo. No severe or serious adverse events were reported in either gadofosveset or placebo groups in this phase II trial. Pooled data revealed no clinically significant trends in adverse events, laboratory assays, vital signs, or oxygen saturation. A QTc prolongation of 2.8 milliseconds was observed at 45 minutes after MS-325 injection; however, this trend was similar to that of the placebo group at the same time point (3.2 milliseconds).

CONCLUSION

Gadofosveset has exhibited a good safety profile and can be safely administered as an intravenous bolus injection. The overall rate and experience of adverse events was similar to that of placebo. The safety profile of gadofosveset is comparable with that of other gadolinium contrast agents as reported in the literature.

Vasovist-enhanced MR angiography

Vasovist (MS-325) is the first intravascular contrast agent approved for use with magnetic resonance angiography in the European Union. Vasovist reversibly binds to albumin, providing extended intravascular enhancement compared to existing extracellular magnetic resonance contrast agents. Prior to approval, Vasovist underwent extensive testing to evaluate the safety and efficacy of the drug; the clinical trials program included blinded, placebo-controlled dose ranging, efficacy in a variety of vascular beds (AIOD, renal, pedal), examination of potential drug interaction with warfarin and comparison with XRA. The clinical trials show that Vasovist-enhanced MR angiography is safe and well-tolerated in patients with vascular disease, effective for the detection of vascular stenosis and aneurysms, significantly more accurate (both more sensitive and specific) than non-contrast MR angiography for the diagnosis of vascular stenoses, and similar to conventional angiography for the overall characterization of vascular disease, without the need for catheterization.

MR Angiography of Aortoiliac Occlusive Disease: A Phase III Study of the Safety and Effectiveness of the Blood-Pool Contrast Agent MS-325

PURPOSE

To evaluate prospectively the safety and effectiveness of aortoiliac magnetic resonance (MR) angiography enhanced with MS-325 (gadofosveset trisodium) at a dose of 0.03 mmol/kg; effectiveness was defined as accuracy relative to the reference standard, conventional angiography.

MATERIALS AND METHODS

Study was approved by institutional review boards of participating institutions, and required national approvals were obtained. Study protocol conformed to Good Clinical Practice guidelines, and informed patient consent was obtained. Patients with known or suspected peripheral vascular disease received 0.03 mmol/kg MS-325 for aortoiliac MR angiography. They were also examined with conventional angiography. MS-325-enhanced MR was evaluated for safety and effectiveness. Along with unenhanced two-dimensional time-of-flight MR angiography, it was compared with conventional angiography for presence of vascular stenosis. Student t tests were used to identify significant improvement in diagnostic sensitivity, specificity, and accuracy, as well as quantitative characterization of stenoses by three blinded readers. Correlations between readers of conventional angiograms were calculated and compared with MR results.

RESULTS

In 174 patients, MS-325-enhanced MR angiography showed significant improvement (P < or = .001) in sensitivity, specificity, and accuracy for diagnosis of clinically significant (> or =50%) stenosis, compared with unenhanced MR. For all readers, areas under the receiver operating characteristic curve for both quantitative and qualitative measures of significant disease increased (P < .001) for MS-325-enhanced MR compared with time-of-flight MR. All readers also expressed higher confidence in diagnosis (P < .001) and found fewer images uninterpretable with MS-325 enhancement. All measures of interpretation accuracy approached corresponding measures of correlation between readers of conventional angiograms. Incidence of severe and serious adverse events with MS-325 was low. No patients were withdrawn from study due to adverse events or abnormalities in laboratory results. There were no clinically important trends in findings at hematology, blood chemistry, urinalysis, electrocardiography, or physical examination.

CONCLUSION

MR angiography with MS-325 provides significant improvement in effectiveness over unenhanced MR (and minimal and transient side effects) at a dose of 0.03 mmol/kg and was safe and effective for MR evaluation of patients with aortoiliac occlusive disease.

Efficacy and safety of MR imaging with liver-specific contrast agent: U.S. multicenter phase III study

PURPOSE

To assess prospectively the efficacy and safety of postcontrast magnetic resonance (MR) imaging with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) compared with that of precontrast MR imaging in patients who are known to have or are suspected of having liver lesions and who are scheduled for hepatic surgery.

MATERIALS AND METHODS

Investigational review board approval and written informed consent were obtained. HIPAA went into effect after data collection. A total of 172 patients were enrolled. After precontrast MR imaging, 169 patients (94 men, 75 women; mean age, 61 years; age range, 19-84 years) received an intravenous bolus of 25 micromol/kg Gd-EOB-DTPA and underwent dynamic gradient-recalled-echo and delayed MR imaging 20 minutes after injection. Arterial and portal phase computed tomography (CT) were performed within 6 weeks of MR imaging. The standard of reference was surgery with intraoperative ultrasonography (US) and biopsy and/or pathologic evaluation of resected liver segments and/or 3-month follow-up of nonresected segments if intraoperative US was not available. Three blinded reviewers and unblinded site investigators identified liver lesions on segment maps. The Wilcoxon signed rank test was used to compare differences in per-patient sensitivity of precontrast and postcontrast MR images. Adverse events were recorded, and patient monitoring and laboratory assay were performed at time of injection and up to 24 hours after contrast material administration.

RESULTS

At MR imaging, 316 lesions were identified in 131 patients. In 77% (P = .012), 72% (P = .15), and 71% (P = .027) of patients for readers 1, 2, and 3, respectively, more lesions were seen at precontrast and postcontrast MR imaging combined than at precontrast MR imaging alone. Sensitivity values for blinded readings were significantly greater at postcontrast MR imaging than at precontrast MR imaging for two of three blinded readers. For all blinded readers, combined precontrast and postcontrast MR images showed no difference in sensitivity compared with helical CT scans. The use of MR imaging, however, yielded fewer patients with at least one false-positive lesion (37%, 31%, and 34% of patients for readers 1, 2, and 3, respectively) than did helical CT (45%, 36%, and 43% of patients for readers 1, 2, and 3, respectively).

CONCLUSION

Compared with precontrast MR imaging, postcontrast MR imaging with Gd-EOB-DTPA demonstrated improved sensitivity for lesion detection in the majority of blinded readers, with no substantial adverse events.

Aortoiliac Occlusive Disease in Patients with Known or Suspected Peripheral Vascular Disease: Safety and Efficacy of Gadofosveset-enhanced MR Angiography—Multicenter Comparative Phase III Study

PURPOSE

To prospectively determine the safety and efficacy of the gadolinium-based blood pool magnetic resonance (MR) imaging contrast agent gadofosveset in patients known to have or suspected of having peripheral vascular disease.

MATERIALS AND METHODS

Ethical committee approval and patient written informed consent were obtained. This study was compliant with the Health Insurance Portability and Accountability Act. Adults known or suspected to have peripheral vascular disease received gadofosveset (0.03 mmol per kilogram of body weight) for MR angiography of the aortoiliac region. Gadofosveset-enhanced MR angiography and unenhanced two-dimensional time-of-flight MR angiography were compared with the reference standard, conventional angiography, for the presence of vascular stenosis. All patients were monitored for adverse events with hematologic analysis, analysis of blood chemistry, urinalysis, and electrocardiographic parameters; these methods were analyzed to determine safety.

RESULTS

A total of 274 patients were enrolled at 37 centers. Gadofosveset-enhanced MR angiography showed significant improvement (P < .001) compared with unenhanced MR angiography for each of the readers for diagnosis of clinically significant (> or = 50%) stenosis. Specificity and accuracy were significantly greater for three readers, and sensitivity increased significantly for two readers. For all readers, the area under the receiver operator characteristic curve for both quantitative and qualitative measures of significant disease increased (P < .001) for gadofosveset-enhanced MR angiography versus two-dimensional time-of-flight MR angiography. All readers also expressed more confidence in diagnosis (P < .001) and found fewer images to be uninterpretable (0.5% vs 11.0%). The most common adverse events were as follows: feeling hot, 12 (4.4%) patients; nausea, 10 (3.6%) patients; headache, nine (3.3%) patients; and burning sensation, eight (2.9%) patients. Only four serious adverse events were reported, in three patients, and all events were rated as unlikely related to the drug. No patients were excluded because of adverse events or laboratory abnormalities. There were no clinically important trends in the findings of hematologic analysis, blood chemistry, urinalysis, electrocardiography, or physical examination.

CONCLUSION

On the basis of substantial improvements over non-contrast MR angiography in efficacy and a minimal and transient side-effect profile, gadofosveset was found to be safe and effective for MR angiography in patients known or suspected to have peripheral vascular disease.

Conspicuity of liver hemangiomas: Short tau inversion recovery, T1, and T2 imaging with gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid

PURPOSE

To compare conspicuity of liver hemangiomas on STIR, T1-weighted, and T2-weighted magnetic resonance (MR) images before and after administration of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) (hepatocellular contrast agent), using contrast-to-noise ratios (CNRs).

MATERIALS AND METHODS

Thirteen hemangiomas were imaged using breath-hold gradient echo (GRE) T1, fat-saturated turbo spin echo (TSE)-T2, and short tau inversion recovery (STIR) sequences. Background noise and signal-to-noise ratios (SNRs) for liver and hemangioma, along with CNR for normal liver and hemangioma, were measured on each sequence before and after administration of Gd-EOB-DTPA. Hemangioma conspicuity was also evaluated qualitatively.

RESULTS

After Gd-EOB-DTPA administration, the quantitative liver SNR decreased 54% on STIR, increased 45% on T1-weighted images, and increased 14.5% on TSE-T2-weighted images. The CNR for liver and hemangioma increased 50% on STIR images (P < 0.0001), increased 46% on T1-weighted imaging (P = 0.0033), and increased 22% on TSE-T2-weighted MR imaging (MRI) (P = 0.0083). After contrast, the CNR for TSE-T2 images was greater than those for both the T1 and STIR images (P < 0.0001 for both). Qualitatively, signal change was visually apparent in the liver on T1 and STIR, but not on T2 images or in the hemangiomas on any sequence.

CONCLUSION

Despite the statistically significant T1 and STIR increase in CNR, liver hemangiomas were most conspicuous on TSE-T2 images after Gd-EOB-DTPA. This pilot study with hemangiomas highlights the newly recognized potential benefit of TSE-T2 imaging with hepatocellular contrast.

MR Coronary Angiography with SH L 643 A: Initial Experience in Patients with Coronary Artery Disease

PURPOSE

To prospectively assess the accuracy of breath-hold three-dimensional magnetic resonance (MR) coronary angiography with the gadolinium-based intravascular contrast agent SH L 643 A in patients with coronary artery disease.

MATERIALS AND METHODS

Twelve patients (seven men, five women; age range, 46-78 years; mean age, 61.3 years) with angiographically proved coronary artery disease (luminal narrowing >50%) underwent breath-hold three-dimensional MR coronary angiography before and after injection of SH L 643 A (0.1 mmol gadolinium per kilogram body weight). For all MR examinations, signal-to-noise ratio and contrast-to-noise ratio were measured. Image quality was assessed with a four-point scale. Conventional angiograms and MR angiograms were evaluated for depiction of the left main, proximal and middle left anterior descending, proximal left circumflex, and proximal and middle right coronary artery segments in a blinded fashion by two experienced readers in consensus. Results of this evaluation were compared by using a paired Student t test. P < .05 was considered to indicate a statistically significant difference.

RESULTS

For the 72 coronary artery segments, the contrast-to-noise ratio significantly improved after administration of SH L 643 A, compared with the prior ratio (9.8 +/- 5.1 [standard deviation] vs 23.0 +/- 8.7; P < .01), whereas the difference in signal-to-noise ratio did not reach statistical significance (25.2 +/- 11.4 vs 29.5 +/- 9.8; P > .3). Image quality significantly improved from a mean of 2.0 +/- 0.9 for nonenhanced images to 2.9 +/- 0.9 (P < .03) for contrast material-enhanced images. The proportion of segments for which images were nondiagnostic decreased from 38% to 10% with application of SH L 643 A. Overall sensitivity and specificity of contrast-enhanced MR coronary angiography for detection of coronary artery disease were 80% and 93%, respectively, and accuracy was 87%.

CONCLUSION

Use of SH L 643 A improves detection of coronary artery disease at three-dimensional MR coronary angiography.

MR angiography with gadofosveset trisodium for peripheral vascular disease: phase II trial

PURPOSE

To evaluate the dose response and safety of gadofosveset trisodium-enhanced magnetic resonance (MR) angiography compared with nonenhanced two-dimensional time-of-flight MR angiography and with x-ray angiography as the standard.

MATERIALS AND METHODS

In this randomized, 20-center, double-blind study, 238 men and women who had peripheral vascular disease or were suspected of having it received intravenous injection of placebo or gadofosveset (0.005, 0.01, 0.03, 0.05, or 0.07 mmol per kilogram of body weight). MR angiographic images were evaluated by three blinded readers, and x-ray angiographic images were evaluated by two readers. Hypothesis testing for the presence of a dose response was based on a linear test for trend for increase in area under the receiver operating characteristic curve as a function of dose for each reader of MR angiographic images independently.

RESULTS

Gadofosveset administration resulted in a dose-dependent increase in diagnostic accuracy for detection of aortoiliac occlusive disease as reflected in the area under the receiver operating characteristic curve for each reader (P <.001). The plateau in effectiveness improvement began at the 0.03 mmol/kg dose. At doses of 0.03 mmol/kg and higher, gadofosveset-enhanced MR angiography provided an approximate 20% increase in accuracy over nonenhanced MR angiography for diagnosis of clinically significant aortoiliac occlusive disease. Gadofosveset exhibited a good safety profile in all dose groups. Three serious adverse events were possibly or probably related to gadofosveset administration. There were no dose-related trends in severe or serious adverse events in patients receiving gadofosveset.

CONCLUSION

A dose of 0.03 mmol/kg of gadofosveset was safe and effective for evaluation of aortoiliac occlusive disease with MR angiography.

Coronary arteries: contrast-enhanced MR imaging with SH L 643A--experience in 12 volunteers

PURPOSE

To assess SH L 643A for three-dimensional breath-hold and respiratory-gated magnetic resonance (MR) imaging in the depiction of coronary arteries.

MATERIALS AND METHODS

Twelve healthy male volunteers underwent either three-dimensional breath-hold (n = 6) or respiratory-gated (n = 6) coronary MR angiography before and after intravenous injection of 0.1 mmol SH L 643A per kilogram of body weight. For nonenhanced and contrast material-enhanced examinations, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements were obtained. Image quality was assessed in consensus with a five-point scale. Statistical analysis of nonenhanced and contrast-enhanced images was based on a two-tailed paired Student t test. A P value at the.05 significance level was used.

RESULTS

Overall statistically significant improvement in CNR was observed after administration of SH L 643A compared with that on nonenhanced images (8.7 +/- 5.3 [SD] vs 23.6 +/- 7.2, P <.01). While SNR of contrast-enhanced images showed improvement over that of nonenhanced images, the difference was not statistically significant (25.4 +/- 0.8 vs 30.2 +/- 16.8, P >.2). Image quality improved from a mean of 3.1 +/- 0.8 for nonenhanced images to 4.0 +/- 0.8 (P <.01) for contrast-enhanced images.

CONCLUSION

SH L 643A causes significant improvement of the blood-myocardium contrast enhancement at coronary MR angiography compared with that with nonenhanced sequences.

Preoperative evaluation of malignant liver tumors: comparison of unenhanced and SPIO (Resovist)-enhanced MR imaging with biphasic CTAP and intraoperative US

The purpose of this study was to evaluate the diagnostic efficacy of iron-oxide-enhanced MRI vs CT during arterial portography (CTAP) and intraoperative ultrasound (IOUS) in detection of liver neoplasms. Seventeen patients with malignant focal liver lesions (liver metastases, n=7), hepatocellular carcinomas (HCC, n=9), and cholangiocellular carcinoma (CCC, n=1) underwent presurgical Resovist-enhanced MRI and CTAP. Two independent observers (A and B) assessed the blinded images of unenhanced and iron-oxide-enhanced MRI vs CTAP for the presence, number, and location of the liver lesions. These results were compared lesion by lesion and segment by segment with the results of intraoperative ultrasound ( n=17) serving as the reference standard. Eighty lesions were detected by intraoperative ultrasound in 17 patients. In comparison with IOUS (lesion-by-lesion analysis) the sensitivity was 86.8% for CTAP, 65% for combined unenhanced MR imaging, and 86.8% for combined Resovist-enhanced MRI as well as 86.8% for the combination of unenhanced and Resovist-enhanced MRI. Compared with the sensitivity of combined unenhanced MRI the sensitivity of CTAP as well as the sensitivity of combined Resovist-enhanced MRI was significantly higher (p<0.05). False-positive results were much higher in CTAP as compared with combined unenhanced and SPIO-enhanced MRI. Using the segment-by-segment analysis the specificity of combined unenhanced MRI with 100% (96.7-100%) as well as combined Resovist-enhanced MRI with 100% (96.7-100%) was significantly higher (p<0.05) in comparison with the specificity of CTAP with 91.1% (83.2-96.1%). The accuracy of combined unenhanced MRI was 100% (93.2-100%), combined Resovist-enhanced MRI 100% (93.6-100%) and of CTAP 85.2% (72.9-93.4%). In the detection of focal liver lesions iron-oxide-enhanced MR imaging is superior to unenhanced MRI and similar to CTAP.

Eovist Injection and Resovist Injection: two new liver-specific contrast agents for MRI

Eovist Injection (gadolinium-EOB-DTPA) is selectively taken up by hepatocytes, which will increase the signal intensity of normal liver parenchyma on T1-weighted images. This results in improved lesion-to-liver contrast because malignant tumors either do not contain hepatocytes or their functioning is hampered. Following intravenous (i.v.) bolus injection, Eovist Injection is excreted by both the renal and biliary routes. Clinical trials have evaluated the safety and efficacy of Eovist Injection up to a dose of 100 mumol/kg body weight. Resovist Injection (SHU-555A) contains iron-oxide nanoparticles coated with carboxydextran and is administered as an intravenous bolus injection at a fixed-volume dose, dependent on body weight. The uptake of Resovist Injection in the reticuloendothelial (RES) cells results in a decrease of the signal intensity of normal liver parenchyma on both T2- and T1-weighted images. Due to the altered phagocytic distribution and activity, the signal intensity in most metastatic tumors is not affected, resulting in improved lesion-to-liver contrast. Both Resovist Injection and Eovist Injection have exhibited acceptable safety profiles in clinical trials, and have the potential to provide additional information regarding lesion detection, classification, and characterization.

Dynamic MR imaging of liver metastases with Gd-EOB-DTPA

PURPOSE

To assess liver and lesion enhancements by dynamic MR imaging after bolus injection of the hepatobiliary contrast agent gadolinium ethoxybenzyl-diethylenetriamine-pentaacetic acid (Gd-EOB-DTPA) in patients with liver metastases and to compare the effect of different doses.

MATERIAL AND METHODS

A randomized double-blinded trial with doses of 12.5, 25 and 50 micromol/kg Gd-EOB-DTPA was performed in 35 patients with liver metastases. Liver enhancement, tumor enhancement and liver lesion contrast-to-noise (C/N) ratios were calculated from breath-hold gradient echo images (100/5/80 degrees) recorded precontrast and at different times up to 10 min postcontrast.

RESULTS

Normal liver showed a characteristic enhancement pattern, with a rapid enhancement in the first 45 s postcontrast and a slight but significant further increase up to 600 s. The initial enhancement in the lesions was also pronounced, but the enhancement was slightly decreased after 240 s postcontrast. At dose levels of 12.5 and 25 micromol/kg Gd-EOB-DTPA, C/N ratios significantly increased compared to baseline from 90 to 600 s. Postcontrast C/N-values obtained using 50 micromol/kg Gd-EOB-DTPA were not significantly increased, except for the examinations 480 s postcontrast.

CONCLUSION

In liver metastases, C/N ratios obtained with doses of 12.5 and 25 micromol/kg Gd-EOB-DTPA were slightly superior to 50 micromol/kg Gd-EOB-DTPA. This finding is probably due to a more pronounced extracellular effect of the contrast medium at higher doses.

T1 effects of a bolus-injectable superparamagnetic iron oxide, SH U 555 A: dependence on field strength and plasma concentration--preliminary clinical experience with dynamic T1-weighted MR imaging

PURPOSE

To investigate the field strength dependency of relaxivity values with SH U 555 A, concentration-dependent T1 effects, and findings at dynamic T1-weighted magnetic resonance (MR) imaging in patients with focal liver lesions.

MATERIALS AND METHODS

Longitudinal relaxivity (r1) with SH U 555 A was measured in human plasma (0.02-300.00 MHz), and transverse relaxivity (r2) was measured at 10, 20, and 40 MHz. Second, a dilution series in human plasma was used at 1-T, T1-weighted, spin-echo or fast low-angle shot (FLASH) imaging. In 22 patients with focal liver lesions, imaging with the latter sequence was performed with a dose of SH U 555 A of 10 mumol Fe/kg.

RESULTS

The r1 of SH U 555 A decreased with increasing field strength, but was higher at high field strengths than r1 values for gadolinium chelates. Enhancement calculations for different iron concentrations in human plasma demonstrated positive enhancement at concentrations less than 700 mumol Fe/L. Enhancement increased with the degree of T1 weighting and was highest for the FLASH sequence with the shortest TE (+81.4% with 300 mumol Fe/L). Enhancement was positive in the liver for at least 30 seconds and in the spleen for at least 480 seconds.

CONCLUSION

Signal intensity changes at dynamic T1-weighted MR imaging after bolus injection of SH U 555 A can be explained by dynamic changes in iron-plasma concentration.

[T1-weighted dynamic MRI with new superparamagnetic iron oxide particles (Resovist): results of a phantom study as well as 25 patients]

PURPOSE

Evaluation of the diagnostic usefulness of the T1-effect of Resovist (SPIO) for dynamic MRI of the liver.

METHOD

In-vitro measurements of a dilution series with T1-weighted FLASH and SE sequences and investigation of 25 patients with known focal liver lesions with a T2-weighted TSE sequence and a dynamic T1-FLASH sequence.

RESULTS

T1-weighted MRI with Resovist in vitro showed a positive enhancement at low concentrations and a negative enhancement at higher concentrations. In-vivo T1-weighted dynamic MRI liver parenchyma demonstrated a positive enhancement 30 s post contrast, followed by a continuous slope of signal intensity and a negative enhancement (> or = 60 s). Spleen, portal venous vessels and haemangiomas showed an early increase in signal intensity followed by a decreasing positive enhancement, but without negative enhancement. During the perfusion phase metastases showed a small but not significant increase in signal intensity. In 80% a positive ring enhancement could be observed around metastases.

CONCLUSION

Resovist exhibits a diagnostically useful T1-effect. An evaluation of the perfusion of focal liver lesions during the distribution phase is possible with dynamic T1-weighted MRI. This approach may further improve characterisation of focal liver lesions.

Superparamagnetic iron oxide particles (SH U 555 A): evaluation of efficacy in three doses for hepatic MR imaging

PURPOSE

To evaluate the efficacy of SH U 555 A in three doses for magnetic resonance (MR) imaging in the liver and to establish the best postinjection time point for liver MR imaging.

MATERIALS AND METHODS

Pre- and postcontrast image sets obtained in 169 patients after injection of SH U 555 A (randomly, 4, 8, or 16 mumol of iron per kilogram of body weight). Three blinded readers evaluated the precontrast and 10- and 40-minute postcontrast MR images of 54, 58, and 57 patients, respectively.

RESULTS

Statistically significant differences were observed in diagnostic confidence between images obtained with a dose of 4 or 16 mumol Fe/kg (P = .011) and in good or excellent improvement, respectively, in delineation of lesions on 10-minute postcontrast images (P = .001). No apparent differences in the efficacy evaluation were seen between the 10- and 40-minute postcontrast imaging time points.

CONCLUSION

There was a dose-dependent postcontrast improvement in evaluated efficacy parameters (diagnostic confidence, visual evaluations) after injection of SH U 555 A. Accumulation phase imaging could begin as early as 10 minutes after administration.

SPIO-enhanced 2D-TOF MR angiography of the portal venous system: results of an intraindividual comparison

The purpose of this study was to investigate whether MR angiography (MRA) of the portal venous system may be improved by means of superparamagnetic iron oxides (SPIOs) during accumulation phase imaging and to study the underlying contrast mechanisms. MRA of the portal venous system was performed on 48 patients before and after intravenous injection of a new SPIO (Resovist, Schering AG, Berlin, Germany). Resovist, as a predominantly liver parenchymal darkening agent on T2-weighted MR images with uptake into the reticuloendothelial cell system, was administered intravenously by bolus injection of 8 to 12 micromol Fe/kg body weight. Patients were scanned with breath-hold coronal and axial two-dimensional (2D) time of flight (TOF) MRA (TR = 31.0 msec, TE = 9.8 msec, flip angle (FA) = 50 degrees, and 6.9-second acquisition time per section) sequences. Signal intensity values of liver parenchyma, the portal venous system, and background were obtained for quantitative analysis. The clinical relevance of additional plain and contrast-enhanced MRA studies for surgical planning was assessed by independent reading of three readers. Liver signal-to-noise ratio (SNR) significantly decreased following iv injection of Resovist; however, SNR values of the portal veins or hepatic veins did not change significantly. Visibility of the portal venous system improved significantly (tertiary branches visible: pre in 15.2% versus post in 87.0% of patients). Resovist-enhanced 2D-TOF MRA may improve planning of liver resections by better demonstrating the relationship of central liver lesions and vessels on source images. The decrease in liver SNR at a constant vessel SNR after iv injection of Resovist improves MRA of the liver. SPIO-enhanced 2D-TOF MRA scans are superior to plain 2D-TOF MRA studies and may be added for the workup of preoperative patients.

[Dynamic and static MRI using superparamagnetic MRI contrast medium Resovist for visualizing primary and secondary liver tumors]

PURPOSE

To analyse characteristics of benign and malignant liver tumours in dynamic and static MR imaging with the superparamagnetic MR contrast medium Resovist.

MATERIAL AND METHODS

All 30 patients were examined on a 1.5 Tesla MR unit (Magnetom 63 SP, Siemens AG, Erlangen, Germany) using proton density (PD) weighted (w), T2-weighted-spin-echo, a T1-weighted SE, and a T1-weighted FLASH-2 D gradient echo (GRE) sequence before, during and after the application of Resovist. Dynamic imaging was performed using a T2-weighted GRE-sequence (TurboFLASH; TR/TE = 11/30; flip angle = 10 degrees; Tl = 600 ms). Histopathology revealed benign liver lesions in 8 patients and malignant lesions in 22 patients.

RESULTS

Dynamic T2-weighted sequence revealed an early loss of signal intensity in normal liver parenchyma (percentage signal intensity loss (PSIL) = 40.0 +/- 12.2% by 4 mumol Fe/kg, 47.2 +/- 18.8% by 8 mumol Fe/kg and 62.7 +/- 13.0% by 16 mumol Fe/kg), in the spleen, as well as in FNH (PSIL = 49.5 +/- 7.3% by 8 mumol Fe/kg), and regenerating nodules in the first minute after application of Resovist. In two of 4 cases with HCC a short drop in signal intensity was immediately observed after the application, whereas signal intensity remained unchanged in all other malignant liver tumours. Enhanced PDw and T2-weighted SE-sequences revealed an improved detection and delineation of malignant liver lesions versus plain MR imaging. 17 liver lesions of a size lower 10 mm were additionally detected in postcontrast T2-weighted SE-sequences in 4 patients.

CONCLUSION

Dynamic and static versus plain MR imaging of primary and secondary liver lesions is markedly improved by the superparamagnetic contrast material Resovist, especially in case of intravenous bolus application of this liver-specific contrast medium.

Detection of focal liver lesions: CT of the hepatobiliary system with gadoxetic acid disodium, or Gd-EOB-DTPA

PURPOSE

To evaluate the efficacy and safety of gadoxetic acid disodium, or Gd-EOB-DTPA, as a tissue-specific hepatobiliary contrast agent at computed tomography (CT) in patients with liver metastases.

MATERIALS AND METHODS

Fifteen patients with known liver metastases underwent CT before and at 30, 80, and, in seven cases, 150 minutes after initiation of intravenous infusion of 0.2, 0.35, and 0.5 mmol Gd/kg gadoxetic acid disodium (five patients per dose group). Attenuation in liver tissue and metastases was measured at each time point. Visualization of metastases, bile ducts, and gallbladder was graded subjectively by two investigators aware of the dose administered and the imaging time point. Patients were monitored for adverse events clinically, and numerous laboratory tests were performed over the 24 hours after administration of the contrast material.

RESULTS

The net mean increase in liver attenuation with 0.2, 0.35, and 0.5 mmol Gd/kg was 13 HU +/- 4 (standard deviation), 27 HU +/- 6, and 34 HU +/- 8, respectively. Visualization of liver metastases with doses of 0.35 and 0.5 mmol Gd/kg was graded as good or excellent. Visualization of the gallbladder and common bile duct with doses of 0.35 and 0.5 mmol Gd/kg was improved from minimal to excellent in 89% and 57% of patients, respectively, on 80-minute postcontrast scans. No serious adverse events occurred. Four of 15 patients experienced mild or moderate adverse events possibly or probably related to the contrast medium. Levels of aspartate and alanine aminotransferase increased in three patients by 12-26 and 21-48 U/L, respectively, from normal or moderately elevated baseline levels. These changes may be related to the contrast medium or to the metastases.

CONCLUSION

Patient tolerance of gadoxetic acid disodium was acceptable, and liver enhancement and visualization of liver lesions and the biliary system was improved at CT.

Phase II clinical evaluation of Gd-EOB-DTPA: dose, safety aspects, and pulse sequence

PURPOSE

To investigate the efficacy of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) in the detection of focal liver lesions with respect to dose, side effects, and pulse sequence.

MATERIALS AND METHODS

A randomized double-blinded trial was performed in 33 patients with focal solid liver lesions. A bolus of Gd-EOB-DTPA, a liver-specific contrast agent, was intravenously administered at three different doses (12.5, 25, and 50 mumol per kilogram of body weight). Magnetic resonance imaging with different T1-weighted techniques was performed 20 and 45 minutes after administration of Gd-EOB-DTPA. Changes in liver signal intensity, lesion-liver contrast-to-noise ration (C/N), detectable liver lesions, side effects, and adverse events were evaluated.

RESULTS

Gd-EOB-DTPA significantly (P < .05) increased liver signal intensity and lesion-liver C/N within the dose range tested. Lesion detection was improved 20 and 45 minutes after administration of Gd-EOB-DTPA. A dose of 12.5 mumol was sufficient for the detection of focal liver lesions, and the breath-hold, T1-weighted, fast low-angle shot pulse sequence was the most useful. No significant changes in vital signs, clinical laboratory test results, and urinalysis were observed.

CONCLUSION

Gd-EOB-DTPA is an efficient, diagnostically useful, and safe contrast agent.

[New MR contrast media in liver diagnosis. Initial clinical results with hepatobiliary Eovist (gadolinium-EOB-DTPA) and RES-specific Resovist (SH U 555 A)]

The purpose of this work is to describe our initial clinical experience (in 66 patients) with Resovist and Eovist, two new liver-specific MR contrast agents. We focus our report on safety aspects, dose finding, and optimization and technical parameters. Both contrast agents were well tolerated and improved the detectability of focal liver lesions. With Resovist, postcontrast MRI may be started as early as 10 min following injection. The dose of 8 mumol Fe/kg bodyweight was sufficient to achieve diagnostic tumor-liver contrast levels. Since Eovist can also be administered as a bolus, dynamic enhancement patterns may be studied for tumor characterization as well. Breath-hold T1-weighted FLASH images were superior to other T1-weighted techniques with and without fat saturation.

Bilateral primary synchronous renal cell carcinoma

We report a case of bilateral primary "synchronous" renal cell carcinoma (RCC) with different differentiation rates. Computed tomography (CT), ultrasonography (US), angiography, and fine needle aspiration biopsy (FNAB) were performed followed by right radical and left partial nephrectomy. Findings on ultrasonography were non-specific, CT scan showed bilateral solid renal mass. On angiography of the right renal artery no tumoral vessels were seen and FNAB yielded a false negative result on the left side. Histological examination revealed a cystic renal cell carcinoma on the right and a multinodular renal cell carcinoma on the left side. We could not find similar report in the current literature.

Crohn's disease and sclerosing cholangitis: CT and PTC diagnosis, with MR findings

Computed tomography (CT), percutaneous transhepatic cholangiography (PTC) and magnetic resonance imaging (MRI) findings in a case of sclerosing cholangitis associated with Crohn's disease of the colon and terminal ileum are described. CT gives additional information on dilatation of peripheral bile ducts and confirms findings of PTC, i.e. a decreased arborization of the biliary tree, a nodular appearance of the common bile duct and multifocal bile duct strictures. CT findings could be recognized on MRI which provided no additional information.

Is it a haemangioma?

A retrospective study of 92 cases of proven haemangiomas is presented. In this study, we evaluated the degree of confidence of the radiologist in differentiating haemangioma by ultrasound (US), computed tomography (CT), angiography (AR), and magnetic resonance imaging (MRI) in an incidental and an oncologic (high risk) population. The diagnosis of haemangioma was confirmed by surgery, by fine needle aspiration biopsy (FNAB) and by long follow-up. Maximum lesions were diagnosed with high confidence by MRI (88-93%) and by angiography (85-91%) in both incidental and oncologic group. 44% of the lesions were confidently diagnosed in incidental group as compared to the 11% of the lesions in oncologic group by ultrasound. Similarly, lesions were diagnosed with maximum confidence in 76% in incidental group as compared to 48% in oncologic group by dynamic contrast bolus CT. Confidence was also evaluated according to the size of the lesions but due to the low number of lesions in < 1.5 cm category, the difference in the confidence levels was not apparent. We conclude that in high risk group, MRI, if available, should be directly performed after US. In the incidental finding group, if the lesion has typical features, US follow-up every 6 months is sufficient.

Focal nodular hyperplasia of the liver: radiologic findings

A retrospective analysis of the results of ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) of 24 cases (28 lesions) of proven focal nodular hyperplasia (FNH) is presented. While US exhibited nonspecific features, CT frequently showed characteristic features: hypodensity on precontrast scans (69%), transient immediate enhancement after bolus injection (96%), and homogeneity (85%). A scar was noted in 31% of the cases. The typical MR triad of isointensity on T1- and/or T2-weighted (T2-WI), homogeneity, and a scar which shows hyperintensity on T2-WI was seen in only 12% of our cases. The most common finding was homogeneity (94%). In two cases the scar was hypointense on T2-WI. To our knowledge, this finding has not been described before. We conclude that the features of FNH, although fairly constant, are at times indistinguishable from those of other hepatic tumors, such as hepatic adenoma (HA), fibrolamellar hepatocellular carcinoma (FLHCC), small hepatocellular carcinoma, and a hyperplastic nodule. Therefore, a multimodality approach is essential for the correct diagnosis in order to prevent unnecessary surgery.

Unusual cystic liver lesions: a pictorial essay

Cystic liver lesions are being increasingly detected by ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI). These lesions produce a wide spectrum of radiological features. Unfortunately their appearance is not always specific and they may resemble and be mistaken for other lesions. Cystic lesions can be classified into congenital, inflammatory, neoplastic and miscellaneous groups. In this pictorial essay a number of unusual cystic lesions are illustrated with a brief analysis of morphological features of the individual lesion and a diagnostic approach for cystic liver lesions is suggested.