James Carr

Radioembolization results in longer time-to-progression and reduced toxicity compared with chemoembolization in patients with hepatocellular carcinoma

BACKGROUND & AIMS Chemoembolization is one of several standards of care treatment for hepatocellular carcinoma (HCC). Radioembolization with Yttrium-90 microspheres is a novel, transarterial approach to radiation therapy. We performed a comparative effectiveness analysis of these therapies in patients with HCC. METHODS We collected data from 463 patients who were treated with transarterial locoregional therapies (chemoembolization or radioembolization) over a 9-year period. We excluded patients who were not appropriate for comparison and analyzed data from 245 (122 who received chemoembolization and 123 who received radioembolization). Patients were followed for signs of toxicity; all underwent imaging analysis at baseline and follow-up time points. Overall survival was the primary outcome measure. Secondary outcomes included safety, response rate, and time-to-progression. Uni- and multivariate analyses were performed. RESULTS Abdominal pain and increased transaminase activity were more frequent following chemoembolization (P < .05). There was a trend that patients treated with radioembolization had a higher response rate than with chemoembolization (49% vs 36%, respectively, P = .104). Although time-to-progression was longer following radioembolization than chemoembolization (13.3 months vs 8.4 months, respectively, P = .046), median survival times were not statistically different (20.5 months vs 17.4 months, respectively, P = .232). Among patients with intermediate-stage disease, survival was similar between groups that received chemoembolization (17.5 months) and radioembolization (17.2 months, P = .42). CONCLUSIONS Patients with HCC treated by chemoembolization or radioembolization with Yttrium-90 microspheres had similar survival times. Radioembolization resulted in longer time-to-progression and less toxicity than chemoembolization. Post hoc analyses of sample size indicated that a randomized study with > 1000 patients would be required to establish equivalence of survival times between patients treated with these two therapies.

Infarct size by contrast enhanced cardiac magnetic resonance is a stronger predictor of outcomes than left ventricular ejection fraction or end-systolic volume index: prospective cohort study

Objectives: Ejection fraction (EF) and end-systolic volume index (ESVI) are established predictors of outcomes following ST-segment elevation myocardial infarction (STEMI). We sought to assess the relative impact of infarct size, EF and ESVI on clinical outcomes and left ventricular (LV) remodelling. Design: Prospective cohort study. Setting: Academic hospital in Chicago, USA. Patients: 122 patients with STEMI following acute percutaneous reperfusion. Main outcome measures: Death, recurrent myocardial infarction (MI) and heart failure. Methods: Cardiac magnetic resonance imaging was obtained within 1 week following STEMI in 122 subjects. ESVI, EF and infarct size were tested for the association with outcomes over 2 years in 113 subjects, and a repeat study was obtained 4 months later to assess LV remodelling in 91 subjects. Results: Acute infarct size correlated linearly with the initial ESVI (r = 0.69, p<0.001), end-diastolic volume index (EDVI) (r = 0.42, p<0.001) and EF (r = −0.75, p<0.001). All were independently associated with outcomes (one death, one recurrent MI and 16 heart failure admissions). However, infarct size was the only significant predictor of adverse outcomes (p<0.05) by multivariate analysis. The smallest infarct size tertile had an increased EF (49% (SD 8%) to 53% (6%); p = 0.002) and unchanged EDVI (p = 0.7). In contrast, subjects with the largest infarct tertile also had improved EF (32% (9%) to 36% (11%); p = 0.002) at the expense of a dramatic increase in EDVI (86 (19) to 95 (21) ml/m2; p = 0.005). Conclusions: Infarct size, EF and ESVI can predict the development of future cardiac events. Acute infarct size, which is independent of LV stunning and loading, directly relates to LV remodelling and is a stronger predictor of future events than measures of LV systolic performance.

Bicuspid Aortic Cusp Fusion Morphology Alters Aortic Three-Dimensional Outflow Patterns, Wall Shear Stress, and Expression of Aortopathy

Background— Aortic 3-dimensional blood flow was analyzed to investigate altered ascending aorta (AAo) hemodynamics in bicuspid aortic valve (BAV) patients and its association with differences in cusp fusion patterns (right-left, RL versus right-noncoronary, RN) and expression of aortopathy. Methods and Results— Four-dimensional flow MRI measured in vivo 3-dimensional blood flow in the aorta of 75 subjects: BAV patients with aortic dilatation stratified by leaflet fusion pattern (n=15 RL-BAV, mid AAo diameter=39.9±4.4 mm; n=15 RN-BAV, 39.6±7.2 mm); aorta size controls with tricuspid aortic valves (n=30, 41.0±4.4 mm); healthy volunteers (n=15, 24.9±3.0 mm). Aortopathy type (0–3), systolic flow angle, flow displacement, and regional wall shear stress were determined for all subjects. Eccentric outflow jet patterns in BAV patients resulted in elevated regional wall shear stress (P<0.0125) at the right-anterior walls for RL-BAV and right-posterior walls for RN-BAV in comparison with aorta size controls. Dilatation of the aortic root only (type 1) or involving the entire AAo and arch (type 3) was found in the majority of RN-BAV patients (87%) but was mostly absent for RL-BAV patients (87% type 2). Differences in aortopathy type between RL-BAV and RN-BAV patients were associated with altered flow displacement in the proximal and mid AAo for type 1 (42%–81% decrease versus type 2) and distal AAo for type 3 (33%–39% increase versus type 2). Conclusions— The presence and type of BAV fusion was associated with changes in regional wall shear stress distribution, systolic flow eccentricity, and expression of BAV aortopathy. Hemodynamic markers suggest a physiological mechanism by which the valve morphology phenotype can influence phenotypes of BAV aortopathy.

Quiescent-interval single-shot unenhanced magnetic resonance angiography of peripheral vascular disease: Technical considerations and clinical feasibility.

We performed technical optimization followed by a pilot clinical study of quiescent‐interval single‐shot MR angiography for peripheral vascular disease. Quiescent‐interval single‐shot MR angiography acquires data using a modified electrocardiographic (ECG)‐triggered, fat suppressed, two‐dimensional, balanced steady‐state, free precession pulse sequence incorporating slice‐selective saturation and a quiescent interval for maximal enhancement of inflowing blood. Following optimization at 1.5 T, a pilot study was performed in patients with peripheral vascular disease, using contrast‐enhanced MR angiography as the reference standard. The optimized sequence used a quiescent interval of 228 ms, α/2 catalyzation of the steady‐state magnetization, and center‐to‐out partial Fourier acquisition with parallel acceleration factor of 2. Spatial resolution was 2‐3mm along the slice direction and 0.7‐1mm in‐plane before interpolation. Excluding stented arterial segments, the sensitivity, specificity, and positive and negative predictive values of quiescent‐interval single‐shot MR angiography for arterial narrowing greater than 50% or occlusion were 92.2%, 94.9%, 83.9%, and 97.7%, respectively. Quiescent‐interval single‐shot MR angiography provided robust depiction of normal peripheral arterial anatomy and peripheral vascular disease in less than 10 min, without the need to tailor the technique for individual patients. Moreover, the technique provides consistent image quality in the pelvic region despite the presence of respiratory and bowel motion. Magn Reson Med 63:951–958, 2010.

Automated rectilinear self-gated cardiac cine imaging.

ECG‐based gating in cardiac MR imaging requires additional patient preparation time, is susceptible to RF and magnetic interference, and is ineffective in a significant percentage of patients. “Wireless” or “self‐gating” techniques have been described using either interleaved central k‐space lines or projection reconstruction to obtain MR signals synchronous with the cardiac cycle. However, the interleaved, central line method results in a doubling of the acquisition time, while radial streak artifacts are encountered with the projection reconstruction method. In this work, a new self‐gating technique is presented to overcome these limitations. A retrospectively gated TrueFISP cine sequence was modified to acquire a short second echo after the readout and phase gradients are rewound. The information obtained from this second echo was used to derive a gating signal. This technique was compared to ECG‐based gating in 10 healthy volunteers and shown to have no significant difference in image quality. The results indicate that this method could serve as an alternative gating strategy without the need for external physiological signal detection. Magn Reson Med 52:782–788, 2004.

Whole-Heart Coronary Magnetic Resonance Angiography at 3 Tesla in 5 Minutes With Slow Infusion of Gd- BOPTA, a High-Relaxivity Clinical Contrast Agent

T1‐shortening contrast agents have been used to improve the depiction of coronary arteries with breath‐hold magnetic resonance angiography (MRA). The spatial resolution and coverage are limited by the duration of the arterial phase of the contrast media passage. In this study we investigated the feasibility of acquiring free‐breathing, whole‐heart coronary MRA during slow infusion of the contrast media (0.3 ml/s) for prolonged blood signal enhancement time. Ultrashort TR (3 ms) and parallel data acquisition were used to allow the whole‐heart MRA in approximately 5 min. A newly approved gadolinium (Gd)‐based high T1 relaxivity contrast agent, gadobenate dimeglumine ([Gd‐BOPTA]2–), was used and coronary MRA was performed on a whole‐body 3 Tesla (T) system to improve the signal‐to‐noise ratio (SNR). Results from eight volunteers demonstrate that this coronary MRA method is capable of imaging the whole heart in 4.5 ± 0.6 min. Major coronary arteries are well depicted with high SNR (42.4 ± 12.5) and contrast‐to‐noise ratio (CNR; 27.1 ± 7.6). Magn Reson Med 58:1–7, 2007.

Valve-Related Hemodynamics Mediate Human Bicuspid Aortopathy: Insights From Wall Shear Stress Mapping

BACKGROUND Suspected genetic causes for extracellular matrix (ECM) dysregulation in the ascending aorta in patients with bicuspid aortic valves (BAV) have influenced strategies and thresholds for surgical resection of BAV aortopathy. Using 4-dimensional (4D) flow cardiac magnetic resonance imaging (CMR), we have documented increased regional wall shear stress (WSS) in the ascending aorta of BAV patients. OBJECTIVES This study assessed the relationship between WSS and regional aortic tissue remodeling in BAV patients to determine the influence of regional WSS on the expression of ECM dysregulation. METHODS BAV patients (n = 20) undergoing ascending aortic resection underwent pre-operative 4D flow CMR to regionally map WSS. Paired aortic wall samples (i.e., within-patient samples obtained from regions of elevated and normal WSS) were collected and compared for medial elastin degeneration by histology and ECM regulation by protein expression. RESULTS Regions of increased WSS showed greater medial elastin degradation compared to adjacent areas with normal WSS: decreased total elastin (p = 0.01) with thinner fibers (p = 0.00007) that were farther apart (p = 0.001). Multiplex protein analyses of ECM regulatory molecules revealed an increase in transforming growth factor β-1 (p = 0.04), matrix metalloproteinase (MMP)-1 (p = 0.03), MMP-2 (p = 0.06), MMP-3 (p = 0.02), and tissue inhibitor of metalloproteinase-1 (p = 0.04) in elevated WSS regions, indicating ECM dysregulation in regions of high WSS. CONCLUSIONS Regions of increased WSS correspond with ECM dysregulation and elastic fiber degeneration in the ascending aorta of BAV patients, implicating valve-related hemodynamics as a contributing factor in the development of aortopathy. Further study to validate the use of 4D flow CMR as a noninvasive biomarker of disease progression and its ability to individualize resection strategies is warranted.

Evaluation of Peripheral Arterial Disease with Nonenhanced Quiescent-Interval Single-Shot MR Angiography

PURPOSE To assess the diagnostic performance of quiescent-interval single-shot (QISS) magnetic resonance (MR) angiography, a nonenhanced two-dimensional electrocardiographically gated single-shot balanced steady-state free precession examination for the evaluation of symptomatic chronic lower limb ischemia. MATERIALS AND METHODS For this prospective institutional review board-approved, HIPAA-compliant study, the institutional review board waived the requirement for informed patient consent. The QISS nonenhanced MR angiography technique was evaluated in a two-center trial involving 53 patients referred for lower extremity MR angiography for suspected or known chronic peripheral arterial disease (PAD), with contrast material-enhanced MR angiography serving as the noninvasive reference standard. The accuracy of stenosis assessments performed with the nonenhanced MR angiography sequence was evaluated relative to the reference standard. Per-segment, per-region, and per-limb sensitivities and specificities were calculated, and assessments were considered correct only if they were in exact agreement with the reference standard-derived assessments. Generalized estimating equation (GEE) modeling with use of an unstructured binomial logit analysis was used to account for clustering of multiple measurements per case. The sensitivity and specificity of QISS MR angiography for the determination of nonsignificant (<50%) versus significant (50%-100%) stenosis were compared with the sensitivity and specificity of the reference standard. RESULTS The diagnostic performance of nonenhanced MR angiography was found to be nearly equivalent to the diagnostic performances of contrast-enhanced MR angiography and digital subtraction angiography. Non-GEE segment-based analysis revealed that for the two reviewers, nonenhanced MR angiography had sensitivities of 89.7% (436 of 486 segments) and 87.0% (423 of 486 segments) and specificities of 96.5% (994 of 1030 segments) and 94.6% (973 of 1028 segments). CONCLUSION QISS nonenhanced MR angiography offers an alternative to currently used imaging tests for symptomatic chronic lower limb ischemia, for which the administration of iodinated or gadolinium-based contrast agents is contraindicated.

3D Noncontrast MR Angiography of the Distal Lower Extremities Using Flow-Sensitive Dephasing (FSD)-Prepared Balanced SSFP

While three‐dimensional contrast‐enhanced MR angiography (MRA) is becoming the method of choice for clinical peripheral arterial disease (PAD) examinations, safety concerns with contrast administration in patients with renal insufficiency have triggered a renaissance of noncontrast MRA. In this work, a noncontrast‐MRA technique using electrocardiography‐triggered three‐dimensional segmented balanced steady‐state free precession with flow‐sensitive dephasing (FSD) magnetization preparation was developed and tested in the distal lower extremities. FSD preparation was used to induce arterial flow voids at systolic cardiac phase while having little effect on venous blood and static tissues. High‐spatial‐resolution MRA was obtained by means of magnitude subtraction between a dark‐artery scan with FSD preparation at systole and a bright‐artery scan without FSD preparation at mid‐diastole. In nine healthy volunteers, FSD parameters, including the gradient waveform and the first‐order gradient moment, were optimized for excellent MRA image quality. Furthermore, arterial stenosis and occlusion in two peripheral arterial disease patients were identified using the noncontrast‐MRA technique, as confirmed by contrast‐enhanced MRA. In conclusion, FSD‐prepared balanced steady‐state free precession in conjunction with electrocardiography gating and image subtraction provides a promising noncontrast‐MRA strategy for the distal lower extremities. Magn Reson Med, 2009.

The Effect of Pelvic MR Imaging on the Diagnosis and Treatment of Women with Presumed Symptomatic Uterine Fibroids

PURPOSE To determine if magnetic resonance (MR) imaging significantly alters the diagnostic thinking and treatment plans of interventional radiologists during the evaluation of women for uterine fibroid embolization (UFE) for presumed uterine fibroids. MATERIALS AND METHODS At a single institution, interventional radiologists prospectively completed questionnaires (n = 60) before and after MR imaging was performed in their evaluation of women presenting for potential UFE. The questionnaires asked these physicians the probability (0%-100%) of their most likely diagnosis before MR imaging and after receiving the MR imaging information. They were also asked their anticipated and final treatment plans. Diagnostic confidence gains and the proportion of patients with changed initial diagnoses or anticipated management were calculated. The Wilcoxon signed-rank test was used to assess gains in diagnostic confidence. RESULTS MR imaging caused a mean gain in diagnostic confidence of 22% (P <.0001). MR imaging changed initial diagnoses in 11 patients (18%). Immediate clinical management changed in 13 patients (22%). UFE was not performed in 11 of 57 women (19%) who were anticipated before MR imaging to receive UFE. CONCLUSIONS MR imaging significantly alters the diagnoses and treatment plans of interventional radiologists evaluating women with presumed symptomatic fibroids. MR imaging should be considered in all patients before UFE.