Mauricio S. Galizia

Evaluation of the Tarsometatarsal Joint Using Conventional Radiography, CT, and MR Imaging

The tarsometatarsal, or Lisfranc, joint complex provides stability to the midfoot and forefoot through intricate osseous relationships between the distal tarsal bones and metatarsal bases and their connections with stabilizing ligamentous support structures. Lisfranc joint injuries are relatively uncommon, and their imaging findings can be subtle. These injuries have typically been divided into high-impact fracture-displacements, which are often seen after motor vehicle collisions, and low-impact midfoot sprains, which are more commonly seen in athletes. The injury mechanism often influences the imaging findings, and classification systems based primarily on imaging features have been developed to help diagnose and treat these injuries. Patients may have significant regional swelling and pain that prevent thorough physical examination or may have other more critical injuries at initial posttrauma evaluation. These factors may cause diagnostic delays and lead to subsequent morbidities, such as midfoot instability, deformity, and debilitating osteoarthritis. Missed Lisfranc ligament injuries are among the most common causes of litigation against radiologists and emergency department physicians. Radiologists must understand the pathophysiology of these injuries and the patterns of imaging findings seen at conventional radiography, computed tomography, and magnetic resonance imaging to improve injury detection and obtain additional information for referring physicians that may affect the selection of the injury classification system, treatment, and prognosis.

MDCT Necrosis Quantification in the Assessment of Hepatocellular Carcinoma Response to Yttrium 90 Radioembolization Therapy: Comparison of Two-dimensional and Volumetric Techniques

RATIONALE AND OBJECTIVES The purpose of this study is to evaluate the reproducibility and agreement of tumor necrosis quantification performed by two-dimensional and volumetric methods in a cohort of patients with hepatocellular carcinoma (HCC) treated with yttrium-90 ((90)Y) radioembolization. MATERIALS AND METHODS Twenty-nine consecutive patients (21 men, 8 women; mean age 66.6 years; age range, 44-90 years) with HCC treated with (90)Y radioembolization that underwent liver multidetector computed tomography (MDCT) were included. Two independent radiologists evaluated the necrosis proportion of the lesions with two-dimensional (2D) measurements according to the European Association for the Study of the Liver guidelines, and with a volumetric method using a voxel-by-voxel analysis. Interobserver reproducibility for each method was assessed by using within-subject coefficients of variation (WSCV), intraclass correlation coefficients (ICC), and Lins concordance correlation coefficients (LCC). Agreement between both methods was assessed by using the Bland-Altman plot and the paired t-test. RESULTS The volumetric method was more reproducible (WSCV = 27.8%; ICC = 0.914; LCC = 0.909) than the 2D (WSCV = 43.8%; ICC = 0.723; LCC = 0.841). There was a significant difference in the mean calculated necrosis proportions based on 2D and volumetric methods (P = .0129). CONCLUSION Voxel-by-voxel quantification of HCC necrosis is a more reproducible method than 2D analysis.

Myocardial T2-mapping and velocity mapping: Changes in regional left ventricular structure and function after heart transplantation

Monitoring post cardiac transplant (TX) status relies on frequent invasive techniques such as endomyocardial biopsies and right heart cardiac catheterization. The aim of this study was to noninvasively evaluate regional myocardial structure, function, and dyssynchrony in TX patients. Myocardial T2‐mapping and myocardial velocity mapping of the left ventricle (basal, midventricular, and apical short‐axis locations) was applied in 10 patients after cardiac transplantation (49 ± 13years, n = 2 with signs of mild rejection, time between TX and MRI = 1–64 months) and compared to healthy controls (n = 20 for myocardial velocity mapping and n = 14 for T2). Segmental analysis based on the 16‐segment American Heart Association model revealed increased T2 (P = 0.0003) and significant (P < 0.0001) reductions in systolic and diastolic radial and long‐axis peak myocardial velocities in TX patients without signs of rejection compared to controls. Multiple comparisons of individual left ventricular segments demonstrated reductions of long‐axis peak velocities in 50% of segments (P < 0.001) while segmental T2 values were not significantly different. Systolic radial as well as diastolic radial and long‐axis dyssynchrony were significantly (P < 0.04) increased in TX patients indicating less coordinated contraction, expansion, and lengthening. Correlation analysis revealed moderate but significant (P < 0.010) inverse relationships between myocardial T2 and long‐axis peak velocities suggesting a structure–function relationship between altered T2 and myocardial function. Magn Reson Med 70:517–526, 2013.

Evaluation of Hepatocellular Carcinoma Size Using Two-dimensional and Volumetric Analysis : Effect on Liver Transplantation Eligibility

RATIONALE AND OBJECTIVES Milan criteria recommends selection of candidates with hepatocellular carcinoma (HCC) for liver transplantation based on strict tumor size thresholds. The purpose of this study is to compare the effect of two-dimensional and three-dimensional tumor measurements on the selection of candidates for liver transplantation using Milan criteria. MATERIALS AND METHODS This retrospective Health Insurance Portability and Accountability Act-compliant study was approved by our institutional review board. Patient-informed consent was waived. Forty-five HCCs in 19 patients, evaluated with triphasic multidetector row computed tomography scans, were included in the analysis. The largest diameters in each two-dimensional orthogonal plane (Max2D) and within three-dimensional tumor boundaries (Max3D) were calculated for each lesion. Diameters were compared and the eligibility based on lesion size for liver transplantation was assessed. RESULTS The mean Max2D diameter of HCC was 3.2 ± 0.9 cm and the mean Max3D diameter was 3.5 ± 1.2 cm. There was a significant difference between the mean Max2D and Max3D diameters (P < .001). Among the 45 lesions, 22 of them (48.9%) were ineligible for transplantation according to Max2D diameter, whereas 29 of them (64.44%) were ineligible when Max3D diameter was applied (P < .001). CONCLUSION HCC diameter based on 3D measurements is significantly different than the conventional 2D measurements and may affect eligibility for liver transplantation.

Splenic Volume Model Constructed From Standardized One-Dimensional MDCT Measurements

OBJECTIVE The purposes of this study were to construct a model for estimation of splenic volume from standardized one-dimensional diameters of the spleen and to compare that model with the ellipsoid model for estimation of splenic volume. MATERIALS AND METHODS In this retrospective study, segmentation software was used for semiautomated quantification of splenic volume by counting CT voxels in 193 consecutively registered patients. For standardization of one-dimensional measurements, the software was used to measure transaxial diameter in the slice with the largest splenic cross-sectional area. By incorporation of splenic volume and the product of width, thickness, and length into the linear regression equation, a model for estimation of splenic volume was constructed, and its performance was externally assessed. Splenic volume also was calculated with the formula for a prolate ellipsoid. The ellipsoid volume and best-fit volumes were compared with segmented splenic volume by use of Bland-Altman plot and Lin concordance correlation. A value of p < 0.05 denoted statistical significance. RESULTS Splenic width was the best one-dimensional predictor of splenic volume (r = 0.84, p < 0.05). The linear regression fitted model for estimation of splenic volume (V(R)) in the initial 100 patients was V(R) = (0.36 × W × T × L) + 28, where W is width, T is thickness, and L is length (R(2) = 0.91, p < 0.05) and was externally validated by estimation of splenic volume in the other 93 patients. Compared with that observed with use of the ellipsoid formula, mean bias decreased from 22.57% to 0.93%, and the Lin coefficient increased from 0.81 to 0.96 with application of the best-fit model for calculation of splenic volume. CONCLUSION The best-fit model V(R) = (0.36 × W × T × L) + 28 is more optimized than the ellipsoid formula and is associated with less bias for estimation of splenic volume.

Quiescent-Inflow Single-Shot Magnetic Resonance Angiography Using a Highly Undersampled Radial k-Space Trajectory

We hypothesized that high undersampling factors could be used in conjunction with radial quiescent‐inflow single‐shot magnetic resonance angiography (MRA) to accelerate the data acquisition and enable multislice acquisitions.

Improved characterization of popliteal aneurysms using gadofosveset-enhanced equilibrium phase magnetic resonance angiography

Although standard magnetic resonance angiography (MRA) has many advantages in the evaluation of peripheral artery disease, it has poorer spatial resolution compared with computed tomographic angiography and digital subtraction angiography. The MRA blood pool contrast agents have an extended half-life. By allowing longer imaging times, MRA enables the acquisition of high-resolution images as well as providing simultaneous visualization of both arteries and veins. Two cases of popliteal artery aneurysm are presented, in which MRA with a blood pool contrast agent provided critical clues to the correct diagnosis: a traumatic pseudoaneurysm of the popliteal artery caused by a femoral osteochondroma and a large fusiform popliteal aneurysm compressing the adjacent popliteal vein, causing venous congestion and leg pain.

Congenital heart disease in adults: Quantitative and qualitative evaluation of IR FLASH and IR SSFP MRA techniques using a blood pool contrast agent in the steady state and comparison to first pass MRA

OBJECTIVES To evaluate magnetic resonance angiography sequences during the contrast steady-state (SS-MRA) using inversion recovery (IR) with fast low-angle shot (IR-FLASH) or steady-state free precession (IR-SSFP) read-outs, following the injection of a blood-pool contrast agent, and compare them to first-pass MR angiography (FP-MRA) in adults with congenital heart disease (CHD). MATERIALS AND METHODS Twenty-three adult patients with CHD who underwent both SS-MRA and FP-MRA using a 1.5-T scanner were retrospectively identified. Signal-to-noise and contrast-to-noise ratios were obtained at eight locations within the aorta and pulmonary vessels.. Image quality and the presence of artifacts were subjectively assessed by two radiologists. The presence of pathology was noted and given a confidence score. RESULTS There was no difference in vessel dimensions among the sequences. IR-SSFP showed better image quality and fewer artifacts than IR-FLASH and FP-MRA. Confidence scores were significantly higher for SS-MRA compared to FP-MRA. Seven cases (30.4%) had findings detected at SS-MRA that were not detected at FP-MRA, and 2 cases (8.7%) had findings detected by IR-SSFP only. CONCLUSION SS-MRA of the thoracic vasculature using a blood pool contrast agent offers superior image quality and reveals more abnormalities compared to standard FP-MRA in adults with CHD, and it is best achieved with an IR-SSFP sequence. These sequences could lead to increased detection rates of abnormalities and provide a simpler protocol image acquisition.

Analysis of the thoracic aorta using a semi-automated post processing tool

OBJECTIVE To evaluates a semi-automated method for Thoracic Aortic Aneurysm (TAA) measurement using ECG-gated Dual Source CT Angiogram (DSCTA). METHODS This retrospective HIPAA compliant study was approved by our IRB. Transaxial maximum diameters of outer wall to outer wall were studied in fifty patients at seven anatomic locations of the thoracic aorta: annulus, sinus, sinotubular junction (STJ), mid ascending aorta (MAA) at the level of right pulmonary artery, proximal aortic arch (PROX) immediately proximal to innominate artery, distal aortic arch (DIST) immediately distal to left subclavian artery, and descending aorta (DESC) at the level of diaphragm. Measurements were performed using a manual method and semi-automated software. All readers repeated their measurements. Inter-method, intra-observer and inter-observer agreements were evaluated according to intraclass correlation coefficient (ICC) and Bland-Altman plot. The number of cases with manual contouring or center line adjustment for the semi-automated method and also the post-processing time for each method were recorded. RESULTS The mean difference between semi-automated and manual methods was less than 1.3mm at all seven points. Strong inter-method, inter-observer and intra-observer agreement was recorded at all levels (ICC ≥ 0.9). The maximum rate of manual adjustment of center line and contour was at the level of annulus. The average time for manual post-processing of the aorta was 19 ± 0.3 min, while it took 8.26 ± 2.1 min to do the measurements with the semi-automated tool (Vitrea version 6.0.0.1 software). The center line was edited manually at all levels, with most corrections at the level of annulus (60%), while the contour was adjusted at all levels with highest and lowest number of corrections at the levels of annulus and DESC (75% and 0.07% of the cases), respectively. CONCLUSION Compared to the commonly used manual method, semi-automated measurement of vessel dimensions is feasible in the thoracic aorta with the advantage of reduced post-processing time.

Clinical utility of cardiac magnetic resonance T2 mapping for acute myocardial edema

Objective To evaluate the potential clinical utility of T2 quantitative mapping for myocardial edema in acute disease pathology - myocarditis, myocardial infarction, TakoTsubo cardiomyopathy, and transplant rejection. Background Edema is ag eneric tissue response to acute myocardial injury and, therefore; a potential marker of impending tissue damage. Currently in clinical use, T2 weighted imaging provides a qualitative technique in assessing myocardial edema. We hypothesize that quantitative T2 mapping in patients with suspected cases of myocarditis, myocardial infarction (AMI), and cardiac transplant rejection will provide a more sensitive and specific diagnostic prediction than with T2W imaging, and add to other imaging techniques. Method