Dose optimization for dynamic time-resolved contrast-enhanced 3D MR angiography of pulmonary circulation

Radiological Evaluation and Endovascular Treatment of Hemoptysis

Hemoptysis can be a life-threatening condition that warrants urgent investigation and intervention. Common causes include bronchiectasis, chronic obstructive pulmonary disease, tuberculosis, and malignancy. Computed tomography angiography is an accurate imaging modality for assessment of hemoptysis. The bronchial arteries are the source of bleeding in most cases of hemoptysis, and bronchial artery embolization is the treatment of choice. The aim of this article is to summarize the pathophysiology, causes, initial management, and diagnostic approach of hemoptysis. Endovascular treatment of hemoptysis, technique, embolic materials, outcomes, complications, and follow-up of patients are discussed.

Time-resolved three-dimensional contrast-enhanced magnetic resonance angiography in patients who have undergone a Fontan operation or bidirectional cavopulmonary connection: initial experience

PURPOSE

To evaluate the usefulness of time-resolved three-dimensional (3D) magnetic resonance angiography (MRA) using diluted contrast agent (CA) in patients who had undergone a Fontan operation or bidirectional cavopulmonary connection (BCPC).

MATERIALS AND METHODS

Time-resolved 3D MRA (10 dynamic data sets, two seconds per dynamic data set) using parallel imaging and keyhole data sampling was performed on 15 patients (median age=10 years, range=1-20 years) who had undergone a Fontan operation (N=11) or BCPC (N=4). Diluted gadolinium (Gd) contrast agent (CA) was intravenously injected into the arm and/or leg veins. The flow dynamics and morphology of pulmonary circulation, and lung perfusion were assessed.

RESULTS

Preferential or balanced pulmonary blood flow from each systemic vein was visualized on time-resolved 3D MRA in all patients. In addition, occlusion/stenosis of the central thoracic vein (N=4) and pulmonary artery (N=6), systemic venous (N=5) and arterial (N=6) collaterals, and lung perfusion defect (N=4) were identified. Persistent hepatic venous plexus, pulmonary arteriovenous malformation, and axillary arteriovenous fistula were delineated in three patients, respectively.

CONCLUSION

Time-resolved 3D MRA with diluted CA is useful for evaluating patients who have undergone a Fontan operation or BCPC because it can reveal the flow dynamics and morphology of pulmonary circulation, and lung perfusion status.

Time-resolved contrast-enhanced MR angiography of the thorax in adults with congenital heart disease

OBJECTIVE

The aim of this study was to evaluate the diagnostic value of time-resolved contrast-enhanced MR angiography in adults with congenital heart disease.

SUBJECTS AND METHODS

Twenty patients with congenital heart disease (mean age, 38 +/- 14 years; range, 16-73 years) underwent contrast-enhanced turbo fast low-angle shot MR angiography. Thirty consecutive coronal 3D slabs with a frame rate of 1-second duration were acquired. The mask defined as the first data set was subtracted from subsequent images. Image quality was evaluated using a 5-point scale (from 1, not assessable, to 5, excellent image quality). Twelve diagnostic parameters yielded 1 point each in case of correct diagnosis (binary analysis into normal or abnormal) and were summarized into three categories: anatomy of the main thoracic vessels (maximum, 5 points), sequential cardiac anatomy (maximum, 5 points), and shunt detection (maximum, 2 points). The results were compared with a combined clinical reference comprising medical or surgical reports and other imaging studies. Diagnostic accuracies were calculated for each of the parameters as well as for the three categories.

RESULTS

The mean image quality was 3.7 +/- 1.0. Using a binary approach, 220 (92%) of the 240 single diagnostic parameters could be analyzed. The percentage of maximum diagnostic points, the sensitivity, the specificity, and the positive and the negative predictive values were all 100% for the anatomy of the main thoracic vessels; 97%, 87%, 100%, 100%, and 96% for sequential cardiac anatomy; and 93%, 93%, 92%, 88%, and 96% for shunt detection.

CONCLUSION

Time-resolved contrast-enhanced MR angiography provides, in one breath-hold, anatomic and qualitative functional information in adult patients with congenital heart disease. The high diagnostic accuracy allows the investigator to tailor subsequent specific MR sequences within the same session.

Pulmonary thromboembolism in children

Pulmonary thromboembolism (PTE) is uncommonly diagnosed in the pediatric patient, and indeed often only discovered on autopsy. The incidence of pediatric PTE depends upon the associated underlying disease, diagnostic tests used, and index of suspicion. Multiple risk factors can be found including: peripartum asphyxia, dyspnea, haemoptysis, chest pain, dehydration, septicemia, central venous lines (CVLs), trauma, surgery, ongoing hemolysis, vascular lesions, malignancy, renal disease, foreign bodies or, uncommonly, intracranial venous sinus thrombosis, burns, or nonbacterial thrombotic endocarditis. Other types of embolism can occur uncommonly in childhood and need to be recognized, as the required treatment will vary. These include pulmonary cytolytic thrombi, foreign bodies, tumor and septic emboli, and post-traumatic fat emboli. No single noninvasive test for pulmonary embolism is both sensitive and specific. A combination of diagnostic procedures must be used to identify suspect or confirmed cases of PTE. This article reviews the risk factors, clinical presentation and treatment of pulmonary embolism in children. It also highlights the current diagnostic tools and protocols used to evaluate pulmonary embolism in pediatric patients.