Evaluation of structure-function relationships in asthma using multidetector CT and hyperpolarized He-3 MRI.

RATIONALE AND OBJECTIVES: Although multiple detector computed tomography (MDCT) and hyperpolarized gas magnetic resonance imaging (HP MRI) have demonstrated ability to detect structural and ventilation abnormalities in asthma, few studies have sought to exploit or cross-validate the regional information provided by these techniques. The purpose of this work is to assess regional disease in asthma by evaluating the association of sites of ventilation defect on HP MRI with other regional markers of airway disease, including air trapping on MDCT and inflammatory markers on bronchoscopy. MATERIALS AND METHODS: Both HP MRI using helium-3 and MDCT were acquired in the same patients. Supervised segmentation of the lung lobes on MRI and MDCT facilitated regional comparisons of ventilation abnormalities in the lung parenchyma. The percentage of spatial overlap was evaluated between regions of ventilation defect on HP MRI and hyperlucency on MDCT to determine associations between obstruction and likely regions of gas trapping. Similarly, lung lobes with high defect volume were compared to lobes with low defect volume for differences in inflammatory cell number and percentage using bronchoscopic assessment. RESULTS: There was significant overlap between sites of ventilation defect on HP MRI and hyperlucency on MDCT suggesting that sites of airway obstruction and air trapping are associated in asthma. The percent (r=0.68; P= .0039) and absolute (r=0.61; P= .0125) number of neutrophils on bronchoalveolar lavage for the sampled lung lobe also directly correlated with increased defect volume. CONCLUSIONS: These results show promise for using image guidance to assess specific regions of ventilation defect or air trapping in heterogeneous obstructive lung diseases such as asthma.

Paul and Juhl interpretação radiológica / Paul and Juhl radiological interpretation

Ao planejarmos a sétima edição deste livro, nosso objetivo era apresentar os elementos básicos do diagnóstico por imagem de forma concisa e clara. Tendo em vista a crescente importância das novas modalidades de imagem, como tomografia computadorizada (TC), ressonância magnética (RM), angiorressonância magnética (Angio-RM), ultra-sonografia e técnicas intervencionistas, expor esse dinâmico assunto em um único volume tornou-se um desafio. Revisões significativas então forjam feitas de forma a incluir técnicas mais recentes e atualizar procedimentos radiológicos já consagrados pelo tempo. Os capítulos sobre o sistema ósseo foram revisados para enfatizar o uso da tomografia computadorizada e da ressonância magnaética, além da cintigrafia óssea. Na seção sobre o sistema nervoso central, a angiorressonância magnética está apresentada e é discutido o valor da RM e da TC em condições que afetam o cérebro e a medula espinhal. O capítulo sobre as vias urinárias foi atualizado de forma a refletir a importância atual da RM, da TC e da ultra-sonografia (US) no estudo dos rins, ureteres, bexiga e próstata

Imaging of lung ventilation and respiratory dynamics in a single ventilation cycle using hyperpolarized He-3 MRI.

PURPOSE: To image respiratory dynamics and three-dimensional (3D) ventilation during inhalation, breath-hold, and exhalation for evaluation of obstructive lung disease using a single dose of hyperpolarized (HP) He-3 during MRI. MATERIALS AND METHODS: A single 2D-3D projections inside Z encoding (PRIZE)-2D acquisition was performed that consisted of a rapid 2D radial acquisition phase during inhalation of the HP He-3, a 3D acquisition phase during a breath-hold interval, and finally the same 2D radial acquisition during a forced exhalation maneuver followed by tidal breathing. The 3D PRIZE acquisition was comprised of radial sampling in the coronal plane and Fourier encoding in the patient's anterior-posterior direction. Nine patients with mild/moderate to severe asthma were studied (two individuals were studied twice) using this technique. RESULTS: Breath-hold and dynamic imaging results showed physiological abnormalities and were compared with results from standard spirometry, body plethysmography, and computed tomography (CT). Dynamic images depicted regions of differential gas clearance and trapping observed during and after forced exhalation that were corroborated as regions of air trapping on CT imaging. CONCLUSION: The 2D-3D PRIZE-2D acquisition allowed for 3D depiction of ventilation during a breath-hold, as well as detection of gas trapping. Imaging results were confirmed with spirometry, body plethysmography, and CT.

Dual-energy subtraction chest radiography: what to look for beyond calcified nodules.

Dual-energy subtraction chest radiography is a robust and powerful tool that improves the ability to detect and accurately diagnose a wide variety of thoracic abnormalities on posteroanterior-lateral chest images. Dual-energy subtraction chest radiography has many advantages over conventional chest radiography that facilitate image interpretation. The major advantage of this imaging technique is that it more clearly depicts calcification, which greatly aids in characterizing pulmonary nodules. Dual-energy subtraction images are also helpful in the recognition of hilar and mediastinal masses; the detection of tracheal narrowing and vascular disease; the identification of bone, pleural, and chest wall abnormalities; and the localization of indwelling devices such as stents and catheters. However, dual-energy subtraction imaging also has some limitations of which the radiologist should be aware and requires a somewhat higher radiation dose than does conventional radiography.

Anatomic pitfalls of the heart and pericardium.

Recent technologic advances have led to more frequent dedicated cross-sectional imaging of the heart. Faster scanning techniques, cardiac gating, and advanced postprocessing software allow improved visualization of finer anatomic details of the heart and pericardium compared with older techniques and software. Use of thin-section computed tomography (CT) or image reformatting in nonaxial planes may be helpful in some cases. The cardiac and pericardial structures are usually readily demonstrated with CT, even if chest CT is performed for evaluation of noncardiac structures. However, radiologists are expected to evaluate all structures on an image, and incidental findings are common. Radiologists must first be familiar with the normal anatomic structures of the heart and pericardium (eg, atria, ventricles, cardiac valves, pericardial recesses, paracardiac structures) to avoid mistaking them for pathologic processes.

PET scan-CT correlation: what the chest radiologist needs to know.

The purpose of this article is to familiarize the chest radiologist with the basics of PET scanning in the chest and to correlate PET findings with thoracic CT findings. After completing this article, the reader should know the following: (a) how PET scanning is performed; (b) the indications for PET scanning in the chest; (c) the significance of SUV and a positive test; (c) the causes of false-positive and false-negative PET scans; and (d) the importance of correlating PET findings with Chest CT findings. The authors conclude that PET and chest CT studies should be read in conjunction to optimize diagnostic accuracy. Interpreting either study alone is fraught with errors, while combined interpretations yield information on both functional activity and anatomic localization. PET-CT hybrid devices that fuse PET and CT data simplify this task and fusion imaging is rapidly becoming the test of choice for evaluating thoracic malignancies.

Thoracic imaging in heart transplantation.

Heart transplantation remains the best treatment option for patients with end-stage heart failure refractory to standard management. Thoracic imaging plays an important role in the preoperative and postoperative evaluation of cardiac transplant recipients. This article reviews the major complications of cardiac transplantation, including acute allograft rejection. Advances in the treatment of organ rejection have improved the long-term survival of cardiac transplant recipients. Rejection is now detected earlier with the help of endomyocardial biopsy and treated aggressively with improved immunosuppressive therapies. The estimated 1-year and 5-year survival rates of heart transplant recipients are 79% and 65%, respectively (2).