Kimberly Kallianos

Influence of pericoronary adipose tissue on local coronary atherosclerosis as assessed by a novel MDCT volumetric method

OBJECTIVE Pericoronary adipose tissue (PCAT) may create a pro-inflammatory state, contributing to the development of coronary artery disease (CAD). We sought to evaluate the feasibility of a novel volumetric PCAT quantification method using a novel threshold based computed tomography approach. In addition we determined the relation between PCAT volumes and CAD. METHODS In 51 patients (49.5±5.1 years, 64.8% male) who underwent 64-slice MDCT, we measured threshold-based PCAT volumes using distance and anatomic-based methods. Using the most reproducible method, we performed the proximal 40-mm distance measurement in three groups as stratified by coronary plaque and high-sensitivity C-reactive protein (hs-CRP) levels: Group 1 (presence of coronary plaque, hs-CRP >2.0 mg/L); an intermediate group (Group 2, no plaque, hs-CRP >2.0 mg/L); and Group 3 (no plaque, hs-CRP<1.0 mg/L). We compared PCAT volumes to the presence of coronary plaque on a patient (n=51) and vessel (n=153) basis. On a subsegment basis (n=1224), we compared PCAT volume to the presence of plaque as well as plaque morphology. RESULTS Distance-based PCAT volume measurements yielded excellent reproducibility with intra-observer intraclass correlation (ICC) of 0.997 and inter-observer ICC of 0.951. On a both a per-patient and per-vessel analysis, adjusted PCAT volume was greater in patients with plaque (Group 1) than without plaque (Groups 2 and 3, p<0.001). No difference in PCAT volume was seen between high and low hs-CRP groups without plaque (p=0.51). Adjusted PCAT volumes were higher in subsegments with plaque as compared without (p<0.001). Additionally, adjusted PCAT volume was greatest in subsegments with mixed plaque followed by non-calcified plaque, calcified plaque, and the lowest volume in segments with no plaque (p<0.001). CONCLUSION In this proof-of-concept study, threshold based PCAT volume assessment is feasible and highly reproducible. PCAT volume is increased in patients and vessels with coronary plaques. Surrounding vessel subsegments with coronary plaque, particularly mixed plaques, have greatest PCAT volume and highlight the effect of local PCAT in the development of coronary atherosclerosis.

Relationship of thoracic fat depots with coronary atherosclerosis and circulating inflammatory biomarkers

The aim of the study was to determine the relationship of various thoracic fat depots with the presence and extent of coronary artery plaque and circulating biomarkers.

Prognostic Role of MR Imaging in Nonischemic Myocardial Disease

The role of cardiac magnetic resonance (MR) imaging as a prognostic tool in patients with ischemic heart disease is well established. However, an increasing body of data now demonstrates that cardiac MR imaging can provide prognostic information in a variety of nonischemic and diffuse myocardial diseases including myocarditis, dilated and hypertrophic cardiomyopathies, sarcoidosis, amyloidosis, and arrhythmogenic right ventricular cardiomyopathy. Cardiac MR imaging can also supply incremental information above established prognostic indicators, providing an additional tool for use in the prediction of disease progression, response to treatment, and risk stratification.

Ferumoxytol MRA for transcatheter aortic valve replacement planning with renal insufficiency

BACKGROUND Computed tomography angiography (CTA) is the test of choice for pre-procedure imaging of transcatheter aortic valve replacement (TAVR) candidates. The iodinated contrast required, however, increases the risk of renal dysfunction in patients with pre-existing renal failure. Ferumoxytol is a magnetic resonance imaging (MRI) contrast agent that can be used with renal failure. Its long vascular resonance time allows gated MRA sequences that approach CTA in image quality. We present respiratory and cardiac gated MRA enabled by ferumoxytol that can be post-processed in an analogous fashion to CTA. METHODS Seven patients with renal failure presenting for TAVR were imaged with respiratory and cardiac gated MRA at 3T using ferumoxtyol for contrast. Aortic annulus, root and peripheral access dimensions were calculated in a fashion identical to that used for CTA. Of these, 6 patients underwent a TAVR procedure and 5 had intraoperative valve assessment with transesophageal echocardiograph (TEE) using standard clinical protocols that employed both two- and three-dimensional techniques. RESULTS Good correlation between MRA aortic annulus measurements and those from TEE were shown in 5 patients with mean annulus area of 392.4mm2 (290-470 range) versus 374.1mm2 (285-440 range), with a pairwise correlation coefficient of 0.92, p=0.029. All patients received Sapien valve implants (one 20mm, three 23mm, and two 26mm valves). Access decisions were guided by MRA with no complications. Annulus sizing resulted in no greater than trace/mild aortic regurgitation in all patients. CONCLUSIONS Ferumoxytol MRA is a safe alternative to CTA in patients with renal failure for pre-TAVR analysis of the aortic root and peripheral access.

Reporting Scan Time Reduces Cardiac MR Examination Duration

CardiacMR(CMR)imagingisusedfor a variety of indications, rangingfrom suspected cardiomyopathy toevaluationofcongenitalheartdefects[1-3].Atourinstitution,theseexam-inations are monitored and tailoredby physicians, with the potential tobecome lengthy and resource inten-sive. CMR examinations have comeunder particular scrutiny in the set-ting of rising health care costs [4,5].Although quality improvementinitiatives typically focus on care im-provement, waste reduction is an al-ternativequalitymeasure [6-9].Onaclinical CMR imaging service, wastetakestheformofaddedscantimeduetoextraneouspulsesequences,repeti-tion of sequences not necessary foraccurate diagnosis, or any extensionof the examination time withoutadded diagnostic value [7]. Waitingtime, whether time spent waiting fora scan to finish or for a radiologist’sassistance, and consequent “under-utilization” of the scanner are exam-plesofwasteonaclinicalservice [10].We observed low compliancewith allotted time slots for CMRexaminationsatourinstitution,de-spite allotted slot times of 90 min(the longest in the department). In2010, more than half of the 518CMR examinations performed ex-ceeded 90 min in length (Table 1).

The role of high-resolution computed tomography in the follow-up of diffuse lung disease

High-resolution computed tomography (HRCT) of the lung is a key component of the multidisciplinary approach to diagnosis in diffuse lung disease (DLD). HRCT also plays an important role in the follow-up of patients with established DLD. In this respect, serial HRCT examinations may provide valuable information that cannot be determined from clinical history and other diagnostic tests, such as pulmonary function tests. Important roles of HRCT in this context include assisting in determining prognosis, monitoring for the efficacy of treatment, detecting progression of disease or complications, and evaluating patients with worsening or acute symptoms. Both clinicians and radiologists should be aware of the expected evolution of HRCT changes in a variety of DLDs. The goals of this paper are to discuss: 1) the expected evolution of HRCT findings over time in common DLDs; 2) the role of serial HRCT examinations in formulating an initial diagnosis; and 3) the role of HRCT in the follow-up of patients with known DLD. HRCT plays an important role in the follow-up of patients with diffuse lung disease http://ow.ly/wzY730c2gRO

Left ventricular myocardial deformation measurements by magnetic resonance Tissue Tracking agrees with tagging (HARP) in healthy volunteers

Background Left ventricular myocardial strain has been described as a potentially useful technique for evaluation and risk stratification of a range of acquired and congenital heart diseases. Tagged acquisition by cardiac MRI has been considered the reference standard for determining myocardial strain; however, this method can be time consuming and the tagged lines may not be visible throughout the cardiac cycle. Tissue Tracking software (Circle Cardiovascular Imaging) is a post-processing method which allows measurements of myocardial strain based on cine cardiovascular magnetic resonance images without the need for additional sequences. Augustine et al. (JCMR 2013) have previously reported reasonable agreement between Feature Tracking (Tom Tec) measurements for circumferential strain and tagging. We aimed to perform a similar comparison between Tissue Tracking software and tagging on a small cohort of normal volunteers.

Dilatation of the ascending aorta is associated with presence of aortic regurgitation in patients after repair of tetralogy of Fallot

To evaluate the association between aortic morphology and elasticity with aortic regurgitation in surgically corrected of tetralogy of Fallot (TOF) patients. We retrospectively identified 72 consecutive patients with surgically corrected TOF and 27 healthy controls who underwent cardiac MRI evaluation. Velocity-encoded cine MRI was used to quantify degree of aortic regurgitation (AR) in TOF patients. Ascending aorta diameters were measured at standard levels on MRA images. Aortic pulse-wave velocity (PWV) was quantified with MRI. Morphological and functional MRI variables were compared between groups of TOF patients with and without clinically relevant AR and controls. The association between aortic morphology and elasticity with the presence of AR was evaluated using univariate and multivariate logistic regression. The majority of TOF patients had only trace AR. Nine TOF patients (12 %) had an AR fraction higher than 15 %. Indexed aorta diameter at the sinotubular junction (p = 0.007), at the RPA level (p = 0.006), and low left ventricular ejection fraction (LVEF) (p = 0.015) showed the strongest associations with the presence of at least mild AR, which persisted after controlling for age and gender. Increased ascending aorta dimension is associated with AR in patients after repair of TOF. LVEF was also low in the group of patients with relevant AR compared to those without, suggesting even mild to moderate AR may contribute to LV dysfunction in these patients. Enlarged ascending aorta may be an indication for precise quantification of regurgitant fraction with MRI, since symptomatic patients may need aortic valve repair when moderate regurgitation is present.

Instituting a Low-dose CT-guided Lung Biopsy Protocol

RATIONALE AND OBJECTIVES We aimed to evaluate whether implementation of a low-dose computed tomography (CT)-guided lung biopsy protocol, with the support of individual radiologists in the section, would lead to immediate and sustained decreases in radiation dose associated with CT-guided lung biopsies. MATERIALS AND METHODS A low-dose CT-guided lung biopsy protocol was developed with modifications of kilovoltage peak, milliamperes, and scan coverage. Out of 413 CT-guided lung biopsies evaluated over a 3-year period beginning in 2009, 175 performed with a standard protocol before the development of a low-dose protocol, and 238 performed with a low-dose protocol. The dose-length product (DLP) was recorded for each lung biopsy and retrospectively compared between the two protocols. Individual radiologist level DLPs were also compared before and after the protocol change. RESULTS The mean biopsy dose decreased by 64.4% with the low-dose protocol (113.8 milligray centimeters versus 319.7 milligray centimeters; P < 0.001). This decrease in radiation dose persisted throughout the entire 18 months evaluated following the protocol change. After the protocol change, each attending radiologist demonstrated a decrease in administered radiation dose. The diagnostic outcome rate and complication rate were unchanged over the interval. CONCLUSIONS Implementation of a low-dose CT-guided lung biopsy protocol resulted in an immediate reduction in patient radiation dose that was seen with all attending radiologists and persisted for at least 18 months. Such an intervention may be considered at other institutions wishing to reduce patient doses.

Beyond Annulus Size: Imaging for TAVR Planning

Purpose of ReviewThe aim of this article is to review the role of imaging in pre-procedural assessment prior to transcatheter aortic valve replacement (TAVR)—with a focus on relevant anatomic findings apart from the size of the aortic annulus.Recent FindingsPre-procedure imaging prior to TAVR heavily emphasizes assessment of the aortic annulus for appropriate valve sizing, with computed tomography angiography (CTA) emerging as the test of choice due to its ability to assess not only the aortic annulus but also the thoracoabdominal aorta and peripheral vasculature. Some patients with underlying kidney disease may be at increased risk of renal dysfunction following contrast-enhanced CTA; however, alternate imaging techniques can be performed to mitigate this risk such as magnetic resonance imaging.SummaryFamiliarity with underlying anatomic variability and pathology relevant to TAVR implantation in addition to annulus size, as well as imaging approaches in patients with renal dysfunction, will allow radiologists to better contribute to multidisciplinary discussion for potential TAVR candidates.