Right ventricular arrhythmia in the absence of arrhythmogenic dysplasia: MR imaging of myocardial abnormalities.

PURPOSE: To evaluate right ventricular abnormalities with magnetic resonance (MR) imaging in patients with arrhythmia but without arrhythmogenic dysplasia. MATERIALS AND METHODS: In 53 patients being evaluated for right ventricular arrhythmia and 15 control subjects, MR imaging was performed to evaluate fixed thinning, fatty replacement, or reduced systolic wall thickening or motion. A diagnosis of idiopathic right ventricular outflow tract tachycardia or indeterminate was assigned for each patient, and the severity of arrhythmia was categorized. RESULTS: Right ventricular abnormalities were revealed in 32 (60%) of the 53 patients: fixed thinning in 27 (84%), fatty replacement in eight (25%), and reduced wall thickening or motion in 31 (97%). Right ventricular abnormalities were found in 35 (76%) of 46 patients with idiopathic right ventricular outflow tract tachycardia and in seven (39%) of 18 patients with indeterminate diagnoses (P = .022). CONCLUSION: Mild right ventricular abnormalities are likely sources for arrhythmias, even in the absence of arrhythmogenic right ventricular dysplasia.

Intramural hematoma of the thoracic aorta: MR image findings and their prognostic implications.

PURPOSE: To evaluate magnetic resonance (MR) imaging findings of intramural hematoma of the thoracic aorta and their relationship to prognosis. MATERIALS AND METHODS: MR images of 22 patients with intramural hematoma of the thoracic aorta were reviewed retrospectively. Site, thickness, degree of mural involvement, and signal intensity on spin-echo (SE) and cine gradient-echo (GRE) images of the hematoma were noted. MR findings of patients who did and those who did not develop complications were compared. RESULTS: Hematoma site was the only MR finding that correlated significantly with patient outcome. Complication frequencies in four (80%) of five patients with hematoma of the ascending aorta (type A) and in two (12%) of 17 patients with hematoma of the descending aorta (type B) were significantly different (P = .009). There were moderately strong correlations between days after symptom onset and signal intensity of the hematoma on SE (r = 0.78) and GRE (r = 0.72) images. MR images of two of three patients who developed early-subacute complications showed signal intensity changes of the hematoma that were consistent with recurrent bleeding. CONCLUSION: Patients with MR findings consistent with type A intramural hematoma of the thoracic aorta should undergo surgery. In cases of type B intramural hematoma of the thoracic aorta, MR imaging can be useful for detecting complete resolution or impending complications of the hematoma.

MR imaging of the thoracic aorta.

The evaluation and diagnosis of thoracic aortic disease using magnetic resonance imaging, including magnetic resonance angiography, is assuming an increasing role in clinical practice. Comparison with other modalities, including computed tomography and echocardiography, is discussed. Newer magnetic resonance imaging techniques, including 3-D breath-hold time-of-flight sequences are highlighted, as well as imaging strategies using standard magnetic resonance imaging techniques. Thoracic aortic disease entities covered include aneurysm, dissection, penetrating ulcers and intramural hematoma, aortitis and infection, tumors, and congenital aortic disease.

Thoracic aortic disease: evaluation using a single MRA volume series.

OBJECTIVE: Use of MRA for thoracic aortic disease (TAD) evaluation has been limited. This report describes an initial experience with TAD evaluation using a single MRA volume series. MATERIALS AND METHODS: A single volume series, based on sequential 2D TOF MRA, was acquired in 30 cases (28 with suspected TAD and 2 normals). Each series was processed using multiplanar reconstruction (MPR) and maximum intensity projection (MIP); resulting tomographic (one base and two MPR) and MIP sets were blindly interpreted by four reviewers to detect TAD and, if present, to diagnose its specific form. For cases incorrectly interpreted, the standard MR images were subsequently interpreted. RESULTS: The TAD categories included aneurysm (n = 13), dissection (n = 9), and arch anomalies (n = 5). Sensitivities were high for TAD overall (89-100%) and TAD in ascending and descending portions; sensitivities were lower for TAD of the arch (two of four reviewers > or = 90% for TAD overall and descending TAD). Specificities for TAD overall had a wider range (67-100%), but were high for ascending, arch, and descending portions (three to four of four reviewers > or = 90% for each). Sensitivities for aneurysms (69-92%) and dissections overall (67-100%) were comparable, as they were in ascending and arch portions; descending dissection was better detected than descending aneurysm (two of four reviewers > or = 90% for ascending or arch aneurysm and for descending dissection); overall specificities (88-100 vs. 81-95%) and specificities in ascending, arch, and descending portions were also comparable (three to four of four reviewers > or = 90% for both in each portion; two of four reviewers > or = 90% for dissection overall). Each reviewer achieved > or = 70% diagnostic accuracy for TAD (one of four reviewers = 85%); accuracies for each category were comparable. Interpretation of standard MR images corrected all detection and most diagnostic (> or = 63%) errors. CONCLUSION: This initial experience with conventional TOF MRA for TAD evaluation is encouraging, but it indicates the potential for advancements in data acquisition and/or postprocessing.

Congenital abnormalities of the thoracic aorta presenting in the adult.

Congenital variations in the development of the thoracic aorta are common. Although there is a spectrum of disease in all age groups, arch anomalies that present in childhood and those that present in the adult tend to be of differing types. Imaging of the arch and its branches, the descending aorta, and the ductus arteriosus or ligamentum arteriosum define the morphology of the arch and permit a reasonable prediction of accompanying congenital heart disease and/or vascular ring.

3D MR myelography.

A three-dimensional (3D) fast imaging with steady state precession sequence structured to maintain constant phase at the radiofrequency pulse, in the presence of motion, was employed to produce high signal intensity of the CSF relative to the extradural and neural structures in 170 consecutive spine MR examinations. In addition to displaying the resulting partitions as two-dimensional (2D) images, the acquisition was subjected to a maximum intensity projection postprocessing algorithm for viewing at multiple angles. The projected images demonstrated a global view of the thecal sac and the dural root sleeves. The global depiction of the thecal sac and root sleeves was equivalent to contrast myelography in 15 patients where comparisons were available. These projection myelographic images, used in conjunction with 2D and reformatted 3D cross-sectional images, may provide clinical services with enough information (in a format with which they are comfortable) to eventually eliminate the need for contrast myelography in the evaluation of extradural disease.