High Tidal Volume, High Positive End Expiratory Pressure and Apneic Breath Hold Strategies (Lung Navigation Ventilation Protocol) With Cone Beam Computed Tomography Bronchoscopic Biopsy of Peripheral Lung Lesions: Results in 100 Patients.

BACKGROUND: A dedicated anesthesia protocol for bronchoscopic lung biopsy-lung navigation ventilation protocol (LNVP)-specifically designed to mitigate atelectasis and reduce unnecessary respiratory motion, has been recently described. LNVP demonstrated significantly reduced dependent ground glass, sublobar/lobar atelectasis, and atelectasis obscuring target lesions compared with conventional ventilation. METHODS: In this retrospective, single-center study, we examine the impact of LNVP on 100 consecutive patients during peripheral lung lesion biopsy. We report the incidence of atelectasis using cone beam computed tomography imaging, observed ventilatory findings, anesthesia medications, and outcomes, including diagnostic yield, radiation exposure, and complications. RESULTS: Atelectasis was observed in a minority of subjects: ground glass opacity atelectasis was seen in 30 patients by reader 1 (28%) and in 18 patients by reader 2 (17%), with good agreement between readers (κ = 0.78). Sublobar/lobar atelectasis was observed in 23 patients by reader 1 and 26 patients by reader 2, also demonstrating good agreement (κ = 0.67). Atelectasis obscured target lesions in very few cases: 0 patients (0%, reader 1) and 3 patients (3%, reader 2). Diagnostic yield was 85.9% based on the AQuIRE definition. Pathology demonstrated 57 of 106 lesions (54%) were malignant, 34 lesions (32%) were benign, and 15 lesions (14%) were nondiagnostic. CONCLUSION: Cone beam computed tomography images confirmed low rates of atelectasis, high tool-in-lesion confirmation rate, and high diagnostic yield. LNVP has a similar safety profile to conventional bronchoscopy. Most patients will require intravenous fluid and vasopressor support. Further study of LNVP and other ventilation protocols are necessary to understand the impact of ventilation protocols on bronchoscopic peripheral lung biopsy.

A Cone Beam CT Bronchoscopy Study of the Ultrathin Cryoprobe for Biopsy of Peripheral Lung Lesions.

BACKGROUND: Compared with the standard cryoprobe, the novel ultrathin 1.1 mm cryoprobe (UTCP) has improved ergonomics, shape memory, and flexibility. The performance of UTCP has demonstrated promising results in several small trials. METHODS: In this single-center, retrospective review, we examine 200 (N=200) consecutive patients referred for cone beam CT bronchoscopic biopsy of peripheral lung lesions. We utilized an extended multimodality approach, including transbronchial needle aspirate, brush, traditional forces biopsies, UTCP biopsies, and BAL. We analyzed tool in lesion, tool touch lesion, center strike rates, and diagnostic yield. We assessed for molecular adequacy and analyzed safety. RESULTS: A total of 222 lesions were biopsied. We achieved a tool in lesion or tool touch lesion confirmation for all biopsy attempts (100%) and a center strike rate of 68%. AQuIRE diagnostic yield was 90%, with 60% malignant, 30% benign lung nodules, and 10% nondiagnostic. UTCP was diagnostic in 3.6 % of peripheral lung lesions biopsies when all other modalities were nondiagnostic; thus, raising our overall diagnostic yield from 86.4% to 90.1%. Our analysis demonstrates superior adequacy for molecular analysis for histologic samples (TBBX or UTCP) versus cytologic samples (FNA) ( P <0.001). Three patients (1.5%) had a pneumothorax, and 1 patient (0.5%) had moderate bleeding. CONCLUSION: UTCP was diagnostic in 3.6% of peripheral lung lesions when all other modalities were nondiagnostic. In the setting of CBCT guidance, UTCP has a similar safety profile to standard biopsy tools. Future trials are warranted to assess UTCP and its impact on peripheral lung lesion biopsies.

Lung Navigation Ventilation Protocol to Optimize Biopsy of Peripheral Lung Lesions.

BACKGROUND: Computed tomography-to-body divergence caused by respiratory motion, atelectasis, diaphragmatic motion and other factors is an obstacle to peripheral lung biopsies. We examined a conventional ventilation strategy versus a lung navigation ventilation protocol (LNVP) optimized for intraprocedural 3-dimensional image acquisition and bronchoscopic biopsy of peripheral lung nodules. METHODS: A retrospective, single center study was conducted in consecutive subjects with peripheral lung lesions measuring <30 mm. Effects of ventilation strategies including atelectasis and tool-in-lesion confirmation were assessed using cone beam computed tomography images. Diagnostic yield was also evaluated. Complications were assessed through 7 days. RESULTS: Fifty subjects were included (25 per group) with 27 nodules in the conventional group and 25 nodules in the LNVP group. Atelectasis was assessed by 2 blinded readers: [reader 1 (R1) and reader 2 (R2)]. Atelectasis was more prevalent in the conventional ventilation group, both for dependent atelectasis (R1: 64% and R2: 68% vs. R1: 36% and R2: 16%, P=0.00014) and sublobar/lobar atelectasis (R1: 48% and R2: 56% vs. R1: 20% and R2: 32%, P=0.01). Similarly, the target lesion was obscured due to atelectasis more often in the conventional ventilation group (R1: 36% and R2: 36% vs. R1: 4% and R2: 8%, P=0.01). Diagnostic yield was 70% for conventional ventilation and 92% for LNVP (P=0.08). CONCLUSION: LNVP demonstrated markedly reduced dependent and sublobar/lobar atelectasis and lesions either partially or completely obscured by atelectasis compared with conventional ventilation. Future prospective studies are necessary to understand the impact of protocolized ventilation strategies for bronchoscopic biopsy of peripheral lung lesions.

Association of intracranial arteriovenous malformation embolization with more rapid rate of perfusion in the peri-nidal region on color-coded quantitative digital subtraction angiography.

BACKGROUND: Hemodynamic alterations post-embolization of intracranial arteriovenous malformations (AVMs) may cause delayed edema/hemorrhage in brain parenchyma adjacent to the lesion. OBJECTIVE: To quantify and compare cerebral perfusion changes in the peri-AVM territory pre- and post-embolization using color-coded quantitative digital subtraction angiography (q-DSA). METHODS: Pediatric intracranial AVM embolization procedures performed over a 5 year period were included. DSA images of all patients were retrospectively assessed using syngo iFlow. Regions of interest (ROI) were selected on anteroposterior and lateral q-DSA views: three in the peri-AVM region; two in parenchyma distant from the AVM. Time-to-peak (TTP) contrast enhancement of ROIs and ∆TTP (TTP at the selected ROI minus TTP at either the ipsilateral internal carotid/vertebral artery) were measured. RESULT: 19 pediatric patients with 19 AVMs (9 males/10 females, mean age 12 years) underwent intracranial AVM embolization: 15/19 AVMs were supplied by the anterior circulation and 4/19 by the posterior circulation. Blood flow was significantly slower post-embolization in the draining vein (19/19) (p<0.01), and the venous sinus outflow (17/19) (p<0.01), by mean difference of 2.01±1.31 s and 1.74±2.04 s. There was significantly increased peri-AVM parenchymal perfusion post-embolization (∆TTP=2.20±0.48 s) compared with pre-embolization (∆TTP=2.52±0.42 s), by an average ∆TTP of 0.33±0.53 s (p=0.014). In contrast, there was no perfusion difference (∆TTP=0.03±0.20 s, p=0.8) between pre- and post-embolization in the distant parenchyma. The size of the AVM was not correlated with change in peri-nidal parenchymal perfusion (r=-0.136, p=0.579). CONCLUSION: This study demonstrates more rapid perfusion in the peri-nidal brain parenchyma post-embolization of the AVM, which supports the theory that increased perfusion in normal tissue surrounding the AVM after embolization may underlie some post-procedural complications.

Prospective evaluation of MR overlay on real-time fluoroscopy for percutaneous extremity biopsies of bone lesions visible on MRI but not on CT in children in the interventional radiology suite.

Magnetic resonance imaging (MRI) often provides better visualization of bone marrow abnormalities than computed tomography (CT) or fluoroscopy, but bone biopsies are usually performed using conventional CT or, more recently, C-arm CT guidance. Biopsies of bone lesions solely visible on MRI are often challenging to localize and require the operator to review the MRI on a separate console to correlate with MRI anatomical landmarks during the biopsy. The MR overlay technique facilitates such biopsies in the angiographic suite by allowing the pre-procedural 3-D MRI to be overlaid on intraprocedural 2-D fluoroscopy. This study describes our initial experience with the MR overlay technique in the angiography suite during pediatric percutaneous extremity bone biopsies of lesions visible on MRI but not on CT or fluoroscopy and demonstrates its utility in relevant clinical cases.

Real-time fluoroscopic needle guidance in the interventional radiology suite using navigational software for percutaneous bone biopsies in children.

BACKGROUND: Navigational software provides real-time fluoroscopic needle guidance for percutaneous procedures in the Interventional Radiology (IR) suite. OBJECTIVE: We describe our experience with navigational software for pediatric percutaneous bone biopsies in the IR suite and compare technical success, diagnostic accuracy, radiation dose and procedure time with that of CT-guided biopsies. MATERIALS AND METHODS: Pediatric bone biopsies performed using navigational software (Syngo iGuide, Siemens Healthcare) from 2011 to 2016 were prospectively included and anatomically matched CT-guided bone biopsies from 2008 to 2016 were retrospectively reviewed with institutional review board approval. C-arm CT protocols used for navigational software-assisted cases included institution-developed low-dose (0.1/0.17 µGy/projection), regular-dose (0.36 µGy/projection), or a combination of low-dose/regular-dose protocols. Estimated effective radiation dose and procedure times were compared between software-assisted and CT-guided biopsies. RESULTS: Twenty-six patients (15 male; mean age: 10 years) underwent software-assisted biopsies (15 pelvic, 7 lumbar and 4 lower extremity) and 33 patients (13 male; mean age: 9 years) underwent CT-guided biopsies (22 pelvic, 7 lumbar and 4 lower extremity). Both modality biopsies resulted in a 100% technical success rate. Twenty-five of 26 (96%) software-assisted and 29/33 (88%) CT-guided biopsies were diagnostic. Overall, the effective radiation dose was significantly lower in software-assisted than CT-guided cases (3.0±3.4 vs. 6.6±7.7 mSv, P=0.02). The effective dose difference was most dramatic in software-assisted cases using low-dose C-arm CT (1.2±1.8 vs. 6.6±7.7 mSv, P=0.001) or combined low-dose/regular-dose C-arm CT (1.9±2.4 vs. 6.6±7.7 mSv, P=0.04), whereas effective dose was comparable in software-assisted cases using regular-dose C-arm CT (6.0±3.5 vs. 6.6±7.7 mSv, P=0.7). Mean procedure time was significantly lower for software-assisted cases (91±54 vs. 141±68 min, P=0.005). CONCLUSION: In our experience, navigational software technology in the IR suite is a promising alternative to CT guidance for pediatric bone biopsies providing comparable technical success and diagnostic accuracy with lower radiation dose and procedure time, in addition to providing real-time fluoroscopic needle guidance.

Real-time three dimensional CT and MRI to guide interventions for congenital heart disease and acquired pulmonary vein stenosis.

To validate the feasibility and spatial accuracy of pre-procedural 3D images to 3D rotational fluoroscopy registration to guide interventional procedures in patients with congenital heart disease and acquired pulmonary vein stenosis. Cardiac interventions in patients with congenital and structural heart disease require complex catheter manipulation. Current technology allows registration of the anatomy obtained from 3D CT and/or MRI to be overlaid onto fluoroscopy. Thirty patients scheduled for interventional procedures from 12/2012 to 8/2015 were prospectively recruited. A C-arm CT using a biplane C-arm system (Artis zee, VC14H, Siemens Healthcare) was acquired to enable 3D3D registration with pre-procedural images. Following successful image fusion, the anatomic landmarks marked in pre-procedural images were overlaid on live fluoroscopy. The accuracy of image registration was determined by measuring the distance between overlay markers and a reference point in the image. The clinical utility of the registration was evaluated as either "High", "Medium" or "None". Seventeen patients with congenital heart disease and 13 with acquired pulmonary vein stenosis were enrolled. Accuracy and benefit of registration were not evaluated in two patients due to suboptimal images. The distance between the marker and the actual anatomical location was 0-2 mm in 18 (64%), 2-4 mm in 3 (11%) and >4 mm in 7 (25%) patients. 3D3D registration was highly beneficial in 18 (64%), intermediate in 3 (11%), and not beneficial in 7 (25%) patients. 3D3D registration can facilitate complex congenital and structural interventions. It may reduce procedure time, radiation and contrast dose.

Effect of protocol choice on phase contrast cardiac magnetic resonance flow measurement in the ascending aorta: breath-hold and non-breath-hold.

Flow assessment with phase contrast magnetic resonance imaging (PC-MRI) protocols is an important component of a comprehensive cardiovascular MR (CMR) assessment. Breath-hold (BH) and non-breath-hold (NBH) PC-MRI protocols are widely available for this imaging modality. Because flow in the great vessels is known to vary with the respiratory cycle, we hypothesized that these 2 approaches might yield different results in the clinical assessment of forward and regurgitant flow in the ascending aorta. Further, given renewed awareness of the possible effect of velocity offsets in PC-MRI, we also sought to evaluate the impact of BH and NBH protocols on this potential source of error. A prospective observational study was performed in 55 consecutive patients referred for clinical CMR of the thoracic aorta. Both BH and NBH protocols were performed at the sinotubular junction and at the mid ascending aorta. Ten additional patients underwent repeated scanning at the mid ascending aorta with both BH and NBH protocols so that protocol variability could be assessed. Finally, ten patients were scanned with both BH and NBH protocols, and phantoms were then imaged with identical imaging parameters so that offset errors associated with each protocol could be evaluated. Forward flow was generally greater with the NBH protocol than with the BH protocol (mean values 102.1 mL vs. 97.9 mL; P = 0.0004). The Bland-Altman limits of agreement were quite wide for all indices (e.g, forward flow, -26.7 mL, +18.2 mL), which suggests that results from BH and NBH protocols cannot be interchanged with confidence. Estimated phase offset errors were similar for both protocols and were generally within acceptable ranges at the mid ascending level, with slightly higher values observed at the sinotubular junction for the BH technique. We observed differences in flow values with BH and NBH protocols for PC-MRI. This finding is relevant to patients imaged serially for the evaluation of cardiac output or valve (aortic or mitral) insufficiency, for whom adherence to one PC-MRI breathing protocol is likely most effective.

Aortic volume as an indicator of disease progression in patients with untreated infrarenal abdominal aneurysm.

OBJECTIVE: The maximal diameter of an abdominal aortic aneurysm (AAA) and the change in diameter over time reflect rupture risk and are used for surgical planning. However, evidence has emerged that aneurysm volume may be a better indicator of AAA remodeling. The purpose of this study was to assess the relationship between the volume and maximal diameter of the abdominal aorta in patients with untreated infrarenal AAA. MATERIALS AND METHODS: This was a retrospective study of 100 patients with infrarenal AAA who were followed for more than 6 months. We examined 2 sets of computed tomography images for each patient, acquired ≥ 6 months apart. The maximal diameter and volume of the infrarenal abdominal aorta were determined by semiautomated segmentation software. RESULTS: At baseline, mean maximal infrarenal diameter was 5.1 ± 1.0 cm and mean aortic volume was 139 ± 72 mL. There was good correlation between the maximal diameter and aortic volume at baseline (r(2) = 0.55; P<0.001). The mean change in maximal diameter between studies was 0.2 ± 0.3 cm and the mean volume change was 19 ± 19 mL. However, the correlation between diameter change and volume change was modest (r(2) = 0.34; P=0.001). Most patients (n = 64) had no measurable change in maximal diameter between studies (≤ 2 mm), but the change in volume was found to vary widely (-2 to 69 mL). CONCLUSION: In patients with untreated infrarenal AAA, a change in aortic volume can occur in the absence of a significant change in maximal diameter. Additional work is needed to examine the relationship between change in AAA volume and outcomes in this patient group.

Utility of free-breathing, whole-heart, three-dimensional magnetic resonance imaging in the assessment of coronary anatomy for congenital heart disease.

The incidence of coronary anomalies is increased in congenital heart disease (CHD). Whole-heart magnetic resonance imaging (MRI) has been proposed as a robust approach to coronary artery imaging without ionizing radiation. The proximal coronary arteries were imaged in 112 CHD patients (63 males) age 17 ± 13 years (range 11 days-68 years) using a navigator-gated, whole-heart, three-dimensional (3D) technique at 1.5 T. Two observers assessed image quality overall and for left anterior descending coronary artery (LAD), left circumflex coronary artery (LCX), and right coronary artery (RCA) using a 5-point scale ranging from 0 (not visible) to 4 (clear margins). Weighted kappa was used to assess interobserver agreement. Coronary artery origins were visible in 99% of the patients. The left main origin was not visualized in one patient, although the LAD, LCX, and RCA were visualized. Eight patients (7%) had anomalies. The overall image quality was 3.3 ± 0.8 for reader 1 and 3.1 ± 1.0 for reader 2. Age had a significant effect on image quality, with younger patients having lower scores. Agreement between readers was moderate (overall kappa, 0.60). Free-breathing, navigator-gated, whole-heart 3D MRI is a useful, robust, and reliable noninvasive technique for assessing coronary artery origins and their proximal course with diagnostic quality in CHD patients.

Orthogonal CSPAMM (OCSPAMM) MR tagging for imaging ventricular wall motion.

Tagged magnetic resonance imaging (MRI) has the ability to directly and non-invasively alter tissue magnetization and produce tags on the deforming tissue [1], [2]. Since its development, the Spatial Modulation of Magnetization (SPAMM) [2] tagging pulse sequence has been widely available and is the most commonly used technique for producing sinusoidal tag patterns. However, SPAMM suffers from tag fading which occurs in the later phases of the cardiac cycle. Complementary SPAMM (CSPAMM) was introduced to solve this problem by acquiring and subtracting two SPAMM images [3]. The drawback of CSPAMM is that it results in doubling of the acquisition time. In this paper, we propose a novel pulse sequence, termed Orthogonal CSPAMM (OCSAPMM), which results in the same acquisition time as SPAMM for 2D deformation estimation while keeping the advantages of CSPAMM. Different from CSPAMM, in OCSPAMM the second tagging pulse orientation is rotated 90 degrees relative to the first one so that motion information can be obtained simultaneously in two directions. A cardiac motion phantom, which independently models cardiac wall thickening and rotation in the human heart was used to show the effectiveness of the proposed pulse sequence.

Aortic stiffness is increased in hypertrophic cardiomyopathy with myocardial fibrosis: novel insights in vascular function from magnetic resonance imaging.

OBJECTIVES: The aim of the study was to determine if patients with hypertrophic cardiomyopathy (HCM), both with and without myocardial fibrosis, have altered aortic stiffness as assessed by magnetic resonance imaging (MRI) pulse wave velocity (PWV) measurements. BACKGROUND: Abnormal aortic stiffness implies an unfavorable prognosis and has been established in a variety of aortic diseases and ischemic cardiomyopathy. However, the relationship between aortic stiffness and HCM has not been studied previously. METHODS: The study was institutional review board approved and Health Insurance Portability and Accountability Act of 1996 compliant. Velocity-encoded MRI was performed in 100 HCM and 35 normal control subjects. PWV was determined between the mid-ascending and -descending thoracic aorta. Delayed-enhancement MRI was acquired for identification of myocardial fibrosis. RESULTS: Mean age was 52.4 years in HCM and 45.3 years in control subjects. The prevalence of myocardial fibrosis in HCM was 70%. PWV was significantly higher in HCM patients compared with control subjects (8.72 +/- 5.83 m/s vs. 3.74 +/- 0.86 m/s, p < 0.0001). PWV was higher (i.e., increased aortic stiffness) in HCM patients with myocardial fibrosis than in those without (9.66 +/- 6.43 m/s vs. 6.51 +/- 3.25 m/s, p = 0.005). CONCLUSIONS: Increased aortic stiffness, as indicated by increased PWV, is evident in HCM patients, and is more pronounced in those with myocardial fibrosis. Further, aortic stiffening may adversely affect left ventricular performance. In addition, increased aortic stiffness correlates with myocardial fibrosis, and may represent another potentially important parameter for risk stratification in HCM, warranting further study.

Association of myocardial fibrosis, electrocardiography and ventricular tachyarrhythmia in hypertrophic cardiomyopathy: a delayed contrast enhanced MRI study.

BACKGROUND: Patients with hypertrophic cardiomyopathy (HCM) are predisposed to ventricular tachyarrhythmia (VT); likely due to myocardial fibrosis or disarray. Delayed hyperenhancement magnetic resonance imaging (DHE-MRI) accurately detects myocardial fibrosis (scar). We sought to determine the association between septal thickness, myocardial scar and VT. METHODS: Sixty-eight patients (mean age 44 years, 69% males) with documented HCM underwent cine MRI (Siemens Sonata or Avanto 1.5 T scanner, Erlangen, Germany) in short axis, 2, 3 and 4-chamber views and maximal interventricular septal thickness was recorded at end-diastole. Corresponding DHE-MR images (8-10 mm thick) were obtained, approximately 20 min after injection of 0.2 mmol/kg of Gadolinium. Scar was determined semi-automatically (as % of total myocardium) using VPT software (Siemens) and defined as intensity >2 SD above viable myocardium in a 12 segment short-axis model at apex, mid LV and base. Presence of VT (documented on ambulatory ECG monitoring) and history of sudden death were recorded. RESULTS: One patient had a history of sudden death and 9 (13%) had VT on ambulatory ECG monitoring. On DHE-MRI, 39 (57%) patients had myocardial scar. Patients with VT had significantly higher scar %, compared to those without: 14% [6, 19] vs. 6% [0, 10], P = 0.01. On logistic regression, only the size of the scar was a significant predictor of VT (P = 0.03). CONCLUSIONS: HCM subjects with VT have a higher % of myocardial scarring noted on DHE-MRI, independent of septal thickness or beta-blocker use.

Influence of coronary artery stenosis severity and coronary collateralization on extent of chronic myocardial scar: insights from quantitative coronary angiography and delayed-enhancement MRI.

OBJECTIVES: In patients with chronic ischemic heart disease, the relationship between coronary artery lesion severity and myocardial scarring is unknown.The purpose of this study was to examine the relationship between proximal coronary artery stenosis severity, the amount of coronary collateralization, and myocardial scar extent in the distal distribution of the affected coronary artery based on both quantitative coronary angiography (QCA) and delayed-enhancement magnetic resonance imaging (DE-MRI). METHODS: Thirty-four patients (26 males, 8 females; age range: 35-86 years) with a coronary artery containing a single, proximal stenosis >/=30% by quantitative coronary angiography (QCA) underwent DE-MRI. The relationship between stenosis severity, collateralization, and myocardial scar morphology (area, transmurality and patchiness) was examined using linear mixed-model ANCOVA. RESULTS: There was a statistically significant correlation between stenosis severity and scar extent (r=0.53, p<0.01). Patients with hemodynamically significant stenoses (>/=70%) exhibited significantly greater collateralization (p<0.05) and scar extent (p<0.01) than patients with <70% stenosis. However, scarring was often found in patients with stenoses <70%. Also, greater stenosis severity (93+/-14%) and mean scar extent (41+/-35%) were found in patients with collaterals than in patients without collaterals (diameter stenosis 48+/-10%, p<0.01) (scar extent 19+/-29%, p=0.01). CONCLUSIONS: Using QCA and DE-MRI, we demonstrate a significant relationship between coronary artery stenosis severity and myocardial scar extent, in the absence of a documented history of acute infarction. The relationship likely reflects increasing ischemia leading to scar formation in the range of angiographically significant stenosis. However, in the absence of collateralization, scar was observed without significant stenosis, especially in females.

Left ventricular torsional mechanics after left ventricular reconstruction surgery for ischemic cardiomyopathy.

OBJECTIVES: Surgical left ventricular reconstruction improves symptoms and potentially prognosis in patients with ischemic cardiomyopathy; however, the effects of reconstruction on myocardial mechanics are not well defined. Therefore, we have computed left ventricular rotation and torsion in patients undergoing left ventricular reconstruction to determine its effects on these quantitative measures of myocardial mechanics. METHODS: Magnetic resonance imaging with tissue grid-tagging was performed in 26 patients (19 male/7 female, 62 +/- 11 years) (mean +/- standard deviation) before (23 +/- 29 days) and after (231 +/- 106 days) left ventricular reconstruction, as well as in 7 healthy volunteers (5 male/2 female, 34 +/- 7 years). Left ventricular rotation was computed at basal and apical short-axis levels; torsion was defined as the difference between apical and basal rotation. RESULTS: Before left ventricular reconstruction, maximal apical rotation was significantly impaired relative to that of healthy volunteers (P = .001), although maximal basal rotation was preserved (P = .84). After reconstruction, maximal torsion did not change significantly: torsion was 6 degrees +/- 3 degrees both before and after reconstruction (P = .84). However, the rate of early diastolic untwist improved significantly after reconstruction (-18 degrees/s +/- 13 degrees/s vs -23 degrees/s +/- 14 degrees/s; P = .04). Furthermore, patients with relatively worse torsion before reconstruction demonstrated more improved function after reconstruction; patients with torsion of less than 6 degrees (n = 12) showed greater improvement in ejection fraction (15% vs 6%; P = .005), torsion (1 degrees vs -1 degrees; P = .01), and diastolic untwist (-9 degrees/s vs -25 degrees/s; P < .001) than did patients with torsion of 6 degrees or more (n = 14). CONCLUSIONS: Torsional mechanics were severely impaired by ischemic cardiomyopathy. On average, left ventricular reconstruction did not affect systolic torsion generation significantly; however, patients with relatively worse torsion did show improvement. Furthermore, the rate of untwist improved after surgery, suggesting that diastolic function was improved.

Noninvasive quantification of fluid mechanical energy losses in the total cavopulmonary connection with magnetic resonance phase velocity mapping.

A major determinant of the success of surgical vascular modifications, such as the total cavopulmonary connection (TCPC), is the energetic efficiency that is assessed by calculating the mechanical energy loss of blood flow through the new connection. Currently, however, to determine the energy loss, invasive pressure measurements are necessary. Therefore, this study evaluated the feasibility of the viscous dissipation (VD) method, which has the potential to provide the energy loss without the need for invasive pressure measurements. Two experimental phantoms, a U-shaped tube and a glass TCPC, were scanned in a magnetic resonance (MR) imaging scanner and the images were used to construct computational models of both geometries. MR phase velocity mapping (PVM) acquisitions of all three spatial components of the fluid velocity were made in both phantoms and the VD was calculated. VD results from MR PVM experiments were compared with VD results from computational fluid dynamics (CFD) simulations on the image-based computational models. The results showed an overall agreement between MR PVM and CFD. There was a similar ascending tendency in the VD values as the image spatial resolution increased. The most accurate computations of the energy loss were achieved for a CFD grid density that was too high for MR to achieve under current MR system capabilities (in-plane pixel size of less than 0.4 mm). Nevertheless, the agreement between the MR PVM and the CFD VD results under the same resolution settings suggests that the VD method implemented with a clinical imaging modality such as MR has good potential to quantify the energy loss in vascular geometries such as the TCPC.

Effects of surgical ventricular restoration on left ventricular function: dynamic MR imaging.

PURPOSE: To retrospectively evaluate with dynamic magnetic resonance (MR) imaging the changes in global and regional left ventricular (LV) function after surgical ventricular restoration (SVR) performed in chronic ischemic heart disease patients with large nonaneurysmal or aneurysmal postmyocardial infarction zones. MATERIALS AND METHODS: The study was performed with institutional review board approval, and a waiver of individual informed consent was obtained. The study was HIPAA compliant. Patients (83 men, 22 women; mean age, 61 years +/- 9 [standard deviation]) were evaluated with MR imaging before and after SVR as follows: pre-SVR examination (n = 105; 25 days +/- 39 before SVR; median, 7 days; range, 1-189 days), early post-SVR examination (n = 95, 7 days +/- 3 after SVR), and late post-SVR (n = 35, 313 days +/- 158 after SVR). Cine MR imaging allowed calculation of ejection fraction and rate-corrected velocity of circumferential fiber shortening (Vcf(C)) for global LV functional evaluation, whereas tagged MR imaging (spatial modulation of magnetization with harmonic phase analysis) permitted assessment of regional circumferential strain (E(C)) with coronary distribution. Vcf(C) and E(C) were computed at both LV base- and mid-LV short-axis levels remote from the site of anteroapical SVR. RESULTS: Prior to SVR, LV dilatation and diminished global and regional LV function were observed. At early post-SVR examination, Vcf(C) had improved significantly but E(C) showed a worsening trend overall, although only E(C )of the right coronary artery at the mid-LV level worsened significantly. At late post-SVR examination, Vcf(C) values were improved when compared with pre-SVR values, although E(C) showed no statistically significant improvement. When compared with that at early post-SVR examination, however, E(C) showed significant improvement in two segments: left anterior descending artery and right coronary artery at mid-LV level. CONCLUSION: Although volume-based indexes of global LV function improve significantly after SVR, regional LV function did not improve significantly; there was evidence of continued LV remodeling after SVR.

Cine delayed-enhancement MR imaging of the heart: initial experience.

This study was performed by using an institutional review board-approved protocol, with waived informed consent and HIPAA compliance. The purpose of this study was to preliminarily evaluate a cine delayed-enhancement (DE) pulse sequence for depiction of wall motion and myocardial scar extent during a single acquisition. The technique is based on inversion-recovery single-shot balanced steady-state free precession magnetic resonance imaging. Cine DE images were acquired in 26 patients (18 men, eight women; age range, 25-84 years; mean age, 61 years+/-13 [standard deviation]). Image contrast was consistent throughout each series. Overall (ie, with both readers' scores averaged), the cine DE imaging-depicted wall motion was scored correctly in 71% of myocardial segments. Scar extent was scored correctly in 76% of segments; in no patient was scarring missed. Cine DE imaging is a promising technique for simultaneous visualization of wall motion and myocardial scar extent.

Coregistered MR imaging myocardial viability maps and multi-detector row CT coronary angiography displays for surgical revascularization planning: initial experience.

PURPOSE: To evaluate assignment of left ventricular (LV) myocardial segments to coronary arterial territories by using coregistered magnetic resonance (MR) imaging and multi-detector row computed tomography (CT) displays; to assess the accuracy of coregistered displays in determining the distribution of clinically important coronary artery disease (CAD) and regional effect of CAD on LV myocardium in patients with chronic ischemic heart disease (CIHD); and to determine the utility of coregistered displays in optimizing surgical revascularization planning. MATERIALS AND METHODS: This study was HIPAA compliant and was approved by the local Institutional Review Board, with waiver of informed consent. Twenty-six patients (19 men, seven women; age, 56 years +/- 12 [+/- standard deviation]) with CIHD underwent MR imaging assessment of myocardial viability and multi-detector row CT assessment of CAD on the same day. For coregistration, a population-based LV model was fit to each data set separately; models were then registered spatially. For data analysis, correspondence between coregistered displays and the 17-segment LV model for assessment of CIHD was evaluated, accuracy of using coregistered displays to evaluate the extent of CAD and myocardial disease was assessed, and utility of coregistered displays in optimizing surgical revascularization planning was determined. RESULTS: Coronary assignment for coregistered displays and the 17-segment LV model differed in 17% of myocardial segments. For the majority of patients, three segments (midanterolateral [62%], apical lateral [73%], and apical inferior [58%]) were discordant. Segments were supplied by the left anterior descending artery, a diagonal branch, or a ramus intermedius with diagonal distribution in all but one case. Coregistered displays were deemed concordant with selective coronary angiography and alternate myocardial imaging in all cases. Overall, surgical planning was potentially enhanced in 83% of cases because, compared with alternate imaging modalities, coregistered displays were believed to demonstrate the relationship between coronary arteries and underlying myocardial tissue more definitively and efficiently (for patients in whom surgery was performed) or more correctly and comprehensively (for a presumably better-tailored surgery). CONCLUSION: Assessment of CIHD can be improved by using coregistered displays that directly relate the condition of LV myocardium to the anatomy of the coronary arteries in individual patients.