MRI of thoracic vascular lesions with emphasis on two-dimensional time-of-flight MR angiography

Magnetic Resonance Angiography of the Thoracic Vasculature: Technique and Applications

Magnetic resonance angiography (MRA) is a powerful clinical tool for evaluation of the thoracic vasculature. MRA can be performed on nearly any magnetic resonance imaging (MRI) scanner, and provides images of high diagnostic quality without the use of ionizing radiation. While computed tomographic angiography (CTA) is preferred in the evaluation of hemodynamically unstable patients, MRA represents an important tool for evaluation of the thoracic vasculature in stable patients. Contrast-enhanced MRA is generally performed unless there is a specific contraindication, as it shortens the duration of the exam and provides images of higher diagnostic quality than noncontrast MRA. However, intravenous contrast is often not required to obtain a diagnostic evaluation for most clinical indications. Indeed, a variety of noncontrast MRA techniques are used for thoracic imaging, often in conjunction with contrast-enhanced MRA, each of which has a differing degree of reliance on flowing blood to produce the desired vascular signal. In this article we review contrast-enhanced MRA, with a focus on contrast agents, methods of bolus timing, and considerations in imaging acquisition. Next, we cover the mechanism of contrast, strengths, and weaknesses of various noncontrast MRA techniques. Finally, we present an approach to protocol development and review representative protocols used at our institution for a variety of thoracic applications. Further attention will be devoted to additional techniques employed to address specific clinical questions, such as delayed contrast-enhanced imaging, provocative maneuvers, electrocardiogram and respiratory gating, and phase-contrast imaging. The purpose of this article is to review basic techniques and methodology in thoracic MRA, discuss an approach to protocol development, and illustrate commonly encountered pathology on thoracic MRA examinations. Level of Evidence 5 Technical Efficacy Stage 3.

Double aortic arch with atresia, tapering and aneurysm of the left arch

An adult male underwent chest radiography for a health check-up. This disclosed both thoracic vascular anomalies and a small nodular shadow in the left side of the superior mediastinum. Axial MRI and three-dimensional volume-rendering MR angiography revealed both a double aortic arch with left atretic arch proximal to the left common carotid artery (subtype 4), and also tapering and aneurysm of the left arch distal to the left subclavian artery. To the authors' knowledge, this report describes the first case of subtype 4 of atretic double arch with left arch atresia. Such thoracic vascular anomalies have been a theoretical possibility, but no cases have been reported to date.

Intraabdominal Pulmonary Sequestration

Bronchopulmonary sequestration is an uncommon developmental abnormality that frequently presents as an incidental mass. Differential diagnosis includes malignancy. Reports of extralobar abdominal pulmonary sequestration in adults are sparse. Only 2.5% of all pulmonary sequestrations are detected below the diaphragm. The authors present a case of a 45-year-old woman and a literature review. Computed tomography, magnetic resonance imaging, and operative and pathologic findings are provided. A review of diagnosis and therapy is presented.

Intralobar pulmonary sequestration diagnosed by MR angiography

A definitive diagnosis of pulmonary sequestration necessitates evidence of a systemic arterial supply to the sequestered lung segment by aortography. We report a case of intralobar pulmonary sequestration in an 11-month-old girl in whom the diagnosis was made by contrast-enhanced magnetic resonance (MR) angiography. Contrast-enhanced MR angiography is the most reliable noninvasive method for the definitive diagnosis of pulmonary sequestration in children.

Video-assisted thoracic surgery lobectomy for pulmonary sequestration

Pulmonary sequestration is a rare developmental abnormality, and the patients usually present with recurrent pneumonia. We report a case of video-assisted thoracic surgery lobectomy in a 32-year-old woman with an intrapulmonary sequestration in the left lower lobe.

Imaging of aortic aneurysms and dissection: CT and MRI

There are numerous approaches to the diagnosis of aortic aneurysms and aortic dissection. Echocardiography, computed tomography (CT), and magnetic resonance imaging (MRI) have enthusiastic proponents promoting each technique, which to some extent obscures the real value of each technique. This review examines the role of these techniques in the diagnosis of aortic disease, with special reference to the most recent published literature and an emphasis on the use of CT and MRI. For most patients with chronic aortic disease, MRI is the most appropriate investigation. In acute situations, CT scanning is usually the most useful technique, with echocardiography added for those with ascending aortic disease or cardiac complications.

Anomalous systemic arterialization to normal basal segments of the left lower lobe: helical CT and CTA findings

PURPOSE

The purpose of this work was to evaluate the helical CT and CT angiography (CTA) findings of anomalous systemic artery (ASA) to the basal segments of the left lower lobe (LLL).

METHOD

Three patients (two had hemoptysis, one was asymptomatic) with blotchy nodular density in the LLL revealed on chest radiographs underwent helical CT and CTA. Bronchoscopy was performed in two of these patients. Angiography and surgery were performed in one patient.

RESULTS

All three patients demonstrated characteristic helical CT and CTA findings including 1) a sigmoid-shaped ASA originating from the lower descending thoracic aorta, with a distal bulbous configuration and four arterial branches supplying the basal segments of the LLL; 2) absence of an interlobar pulmonary artery or presence of a small artery lateral to the truncus basalis; 3) engorged vascular markings in the basal segments of the LLL; and 4) normal tracheobronchial tree and lung parenchyma.

CONCLUSION

The findings in the present three cases suggest that the use of invasive studies such as angiography or bronchoscopy may be obviated in the diagnosis of ASA to the LLL because diagnosis can be provided through a clear set of criteria on helical CT and CTA.