Adam Plotnik

Current treatment of renal artery aneurysms may be too aggressive

OBJECTIVE Most studies recommend repair of renal artery aneurysms (RAAs) >2 cm in diameter in asymptomatic patients, but other studies have suggested that their natural history may be more benign. We hypothesized that rupture and death in patients with asymptomatic RAAs is low and that current recommendations for RAA treatment at 2 cm may be too aggressive. METHODS Retrospective review of all RAAs treated at a tertiary care medical center from 2002 to 2012. RESULTS Fifty-nine RAA were identified in 40 patients (mean age at diagnosis, 56 years; male:female ratio, 17:23); 31 were saccular, 8 were fusiform, and 5 were bilobed. Twenty-nine patients were asymptomatic; the remainder of patients presented with hematuria (n = 4), abdominal pain (n = 3), difficult-to-control hypertension (n = 3), or flank pain (n = 2). Aneurysm location included the main renal artery bifurcation (n = 35), main trunk (n = 7), primary branch (n = 6), pole artery (n = 6), and secondary branch (n = 1). Operative management of RAAs included vein patch (n = 6), prosthetic patch (n = 4), primary repair (n = 3), plication (n = 1), patch and implantation (n = 1), and ex vivo repair (n = 1). Eight asymptomatic RAAs were treated surgically (mean RAA diameter = 2.4 ± 0.1 cm, range, 2-3 cm), with the remaining 33 asymptomatic RAAs being managed conservatively (mean RAA diameter = 1.4 ± 0.1 cm, range, 0.6-2.6 cm). Mean hospital length of stay was 4 days, with no late postoperative complications and 0% mortality. Non-operated patients were followed for a mean of 36 ± 9 months, with no late acute complications and 0% mortality. Mean RAA growth rate of patients with multiple imaging studies was 0.60 ± 0.16 mm/y. CONCLUSIONS The rate of aneurysm rupture and death in our untreated RAA patients is zero, the growth rate is 0.60 ± 0.16 mm/y, and there were no adverse outcomes in asymptomatic RAAs >2 cm that were observed. We may currently be too aggressive in treating asymptomatic RAAs.

Four-dimensional, multiphase, steady-state imaging with contrast enhancement (MUSIC) in the heart: a feasibility study in children.

To develop a technique for high resolution, four‐dimensional (4D), multiphase, steady‐state imaging with contrast enhancement (MUSIC) in children with complex congenital heart disease.

Modified wideband three-dimensional late gadolinium enhancement MRI for patients with implantable cardiac devices

To study the effects of cardiac devices on three‐dimensional (3D) late gadolinium enhancement (LGE) MRI and to develop a 3D LGE protocol for implantable cardioverter defibrillator (ICD) patients with reduced image artifacts.

Reducing view-sharing using compressed sensing in time-resolved contrast-enhanced magnetic resonance angiography

To study temporal and spatial blurring artifacts from k‐space view‐sharing in time‐resolved MR angiography (MRA) and to propose a technique for reducing these artifacts.

Towards the identification of multi-parametric quantitative MRI biomarkers in lupus nephritis☆

PURPOSE To identify potential biomarkers of the renal impairment in lupus nephritis using a multi-parametric renal quantitative MRI (qMRI) protocol including diffusion weighted imaging (DWI), blood oxygen level dependent (BOLD), arterial spin labeling (ASL) and T1rho MRI between a cohort of healthy volunteers and lupus nephritis (LN) patients. MATERIALS AND METHODS The renal qMRI protocol was performed twice with repositioning in between on 10 LN patients and 10 matched controls at 1.5 T. Navigator-gated and breath-hold acquisitions followed by non-rigid image registration were used to control respiratory motion. The repeatability of the 4 MRI modalities was evaluated with the intra-class correlation coefficient (ICC) and within-subject coefficient of variation (wsCV). Unpaired t-test and stepwise logistic regression were carried out to evaluate qMRI parameters between the LN and control groups. RESULTS The reproducibility of the 4 qMRI modalities ranged from moderate to good (ICC=0.4-0.91, wsCV≤12%) with a few exceptions. T1rho MRI and ASL renal blood flow (RBF) demonstrated significant differences between the LN and control groups. Stepwise logistic regression yielded only one significant parameter (medullar T1rho) in differentiating LN from control groups with 95% accuracy. CONCLUSION A reasonable degree of test-retest repeatability and accuracy of a multi-parametric renal qMRI protocol has been demonstrated in healthy volunteers and LN subjects. T1rho and ASL RBF are promising imaging biomarkers of LN.

Safety of Hydroinfusion in Percutaneous Thermal Ablation of Hepatic Malignancies

PURPOSE Hydroinfusion is a commonly used ancillary procedure during percutaneous thermal ablation of the liver that is used to separate and protect sensitive structures from the ablation zone. However, risks of hydroinfusion have not been systematically studied. The purpose of the present study was to systematically examine the frequency and severity of local and systemic complications related to hydroinfusion. MATERIALS AND METHODS From January 2009 to April 2012, 410 consecutive patients underwent percutaneous thermal hepatic tumor ablation. One hundred fifty patients in the study group underwent hydroinfusion and 260 in the control group did not. Patient charts and imaging studies of both groups were reviewed to compare incidences of complications that could potentially be caused by hydroinfusion, including pleural effusion, bowel injury, infection, electrolyte imbalance, and hyperglycemia. RESULTS Pleural effusions were found to occur more commonly in the hydroinfusion group (45.3%) than in the control group (16.5%). Pleural effusions were significantly larger (P < .001) and more likely to be symptomatic (six of 150 patients; P = .006) in the hydroinfusion group than in the control group (one of 260 patients). Multiple patient and tumor characteristics were analyzed for association with development of major hydroinfusion-type complications (requiring therapy or extended/repeat hospitalization). Subcapsular location of tumor was the only variable to reach statistical significance (P = .009), with all major hydroinfusion-type complications (n = 10) occurring in patients with subcapsular tumors. CONCLUSIONS Hydroinfusion is a safe procedure overall. However, pleural effusions occur commonly after hydroinfusion, tend to be moderate or large in size, and are occasionally symptomatic.

Ferumoxytol-enhanced MR Angiography for Vascular Access Mapping before Transcatheter Aortic Valve Replacement in Patients with Renal Impairment: A Step Toward Patient-specific Care

Purpose To assess the technical feasibility of the use of ferumoxytol-enhanced (FE) magnetic resonance (MR) angiography for vascular mapping before transcatheter aortic valve replacement in patients with renal impairment. Materials and Methods This was an institutional review board-approved and HIPAA-compliant study. FE MR angiography was performed at 3.0 T or 1.5 T. Unenhanced computed tomographic (CT) images were used to overlay vascular calcification on FE MR angiographic images as composite fused three-dimensional data. Image quality of the subclavian and aortoiliofemoral arterial tree and confidence in the assessment of calcification were evaluated by using a four-point scale (4 = excellent vascular definition or strong confidence). Signal intensity nonuniformity as reflected by the heterogeneity index (ratio between the mean standard deviation of luminal signal intensity and the mean luminal signal intensity), signal-to-noise ratio, and consistency of luminal diameter measurements were quantified. Findings at FE MR angiography were compared with pelvic angiograms. Results Twenty-six patients underwent FE MR angiography without adverse events. A total of 286 named vascular segments were scored. The image quality score was 4 for 99% (283 of 286) of the segments (κ = 0.9). There was moderate to strong confidence in the ability to assess vascular calcific morphology in all studies with complementary unenhanced CT. The steady-state luminal heterogeneity index was low, and signal-to-noise ratio was high. Interobserver luminal measurements were reliable (intraclass correlation coefficient, 0.98; 95% confidence interval: 0.98, 0.99). FE MR angiographic findings were consistent with correlative pelvic angiograms in all 16 patients for whom the latter were available. Conclusion In patients with renal impairment undergoing transcatheter aortic valve replacement, FE MR angiography is technically feasible and offers reliable vascular mapping without exposure to iodine- or gadolinium-based contrast agents. Thus, the total cumulative dose of iodine-based contrast material is minimized and the risk of acute nephropathy is reduced.

Modified wideband 3D late gadolinium enhancement (LGE) MRI for patients with implantable cardiac devices

Background Late gadolinium enhancement (LGE) cardiac MRI is the clinical gold standard for non-invasive assessment of myocardial viability and plays an important role in guiding catheter ablation of ventricular tachycardia (VT). The majority of VT patients have implanted cardiac devices such as implantable cardioverter defibrillators (ICDs). The presence of ICDs gives rise to strong off-resonance within the myocardium. This produces hyper-intensity (HI) artifacts in LGE, which can mask scar tissue, compromising the diagnostic value of LGE. Recent studies show that HI artifacts can be eliminated by using a wideband inversion recovery (IR) pulse in the LGE sequence. However, the current wideband LGE is a 2D sequence, which limits spatial resolution, especially slice thickness (8 mm). This is problematic for using LGE to guide catheter ablation of VT. High resolution LGE is feasible using a 3D LGE sequence. However, no prior studies have explored 3D LGE under the influence of strong off-resonance imposed by ICDs.

Intervention in Massive Pulmonary Embolus: Catheter Thrombectomy/Thromboaspiration versus Systemic Lysis versus Surgical Thrombectomy

Massive pulmonary embolus (PE), defined as hemodynamic shock from acute PE, is a life-threatening condition. Deaths from massive PE, especially when unsuspected, occur within minutes to hours of onset and as such prompt intervention can be lifesaving. Acute massive PE patients have traditionally been candidates for treatment with intravenous systemic thrombolysis to improve pulmonary artery pressure, arteriovenous oxygenation, and pulmonary perfusion in an effort to reduce mortality. However, patients with contraindications to systemic thrombolysis or those who have failed thrombolysis may benefit from other techniques including endovascular and surgical embolectomy. This article will review the current medical management as well as catheter-directed therapies and surgical embolectomy in the treatment of patients with massive PE.

Myocardial tagging in the polar coordinate system; early clinical experience

Background Quantitative MR myocardial strain analysis is typically performed using rectilinear or Cartesian grid tagging, and regional contractility is visually assessed by the deformation of the grid1. However, it is difficult to visually isolate circumferential and radial components of displacement and strain from parallel straight lines on short axis images. This study evaluates the potential of a polar coordinate tagging system2 for quantification of circumferential myocardial displacement in a variety of clinical conditions.