Siegfried Tuengerthal

Assessment of morphological MRI for pulmonary changes in cystic fibrosis (CF) patients: Comparison to thin-section CT and chest x-ray

Objectives:As pulmonary complications are life limiting in patients with cystic fibrosis (CF), repeated chest imaging [chest x-ray, computed tomography (CT)] is needed for follow up. With the continuously rising life expectancy of CF patients, magnetic resonance imaging (MRI) as a radiation-free imaging modality might become more and more attractive. The goal of this study was to prospectively assess the value of MRI for evaluation of morphologic pulmonary CF-changes in comparison to established imaging modalities. Materials and Methods:Thirty-one CF patients (19 female, 12 male; mean age 16.7 years) with stable lung disease were examined by MRI: HASTE, coronal/transversal (TR/TE/α/TA: infinite/28 ms/180°/18 s), multi-detector computed tomography (MDCT) (30 patients): 120 kV, dose modulated mAs, and chest x-ray (21 patients). Image evaluation: random order, 4 chest radiologists in consensus; chest x-ray: modified Chrispin-Norman score; CT and MRI: modified Helbich score. The maximal attainable score for chest x-ray was 34, for MRI and CT 25. Median scores, Pearson correlation coefficients, Bland-Altman plots, and concordance of MRI to CT on a lobar and segmental basis were calculated. Results:The median MRI and MDCT scores were 13 (min 3, max 20) respectively 13.5 (min 0, max 20). The median chest x-ray score was 14 (min 5, max 32). Pearson correlation coefficients: MRI/CT = 0.80, P < 0.0001; MRI/chest x-ray = 0.63, P < 0.0018; chest x-ray/CT = 0.75, P < 0.0001. The median lobe related concordance was 80% for bronchiectasis, 77% for mucus plugging, 93%, for sacculation/abscesses, and 100% for collapse/consolidation. Conclusions:Morphologic MRI of the lung in CF patients demonstrates comparable results to MDCT and chest x-ray. Because radiation exposure is an issue in CF patients, MRI might have the ability to be used as an appropriate alternative method for pulmonary imaging.

Proton MRI appearance of cystic fibrosis: Comparison to CT

Cystic fibrosis (CF) is the most frequent inherited disorder leading to premature death in the Caucasian population. As life expectancy is limited by pulmonary complications, repeated imaging [chest X-ray, multislice high-resolution computed tomography (MS-HRCT)] is required in the follow-up. Magnetic resonance imaging (MRI) of the lung parenchyma is a promising new diagnostic tool. Its value for imaging lung changes caused by CF compared with CT is demonstrated. MRI performs well when compared with CT, which serves as the gold standard. Its lack in spatial resolution is obvious, but advantages in contrast and functional assessment compensate for this limitation. Thus, MRI is a reasonable alternative for imaging the CF lung and should be introduced as a radiation-free modality for follow-up studies in CF patients. For further evaluation of the impact of MRI, systematic studies comparing MRI and conventional imaging modalities are necessary. Furthermore, the value of the additional functional MRI (fMRI) information has to be studied, and a scoring system for the morphological and functional aspect of MRI has to be established.

Assessment of differential pulmonary blood flow using perfusion magnetic resonance imaging: comparison with radionuclide perfusion scintigraphy.

Objectives:We sought to assess the agreement between lung perfusion ratios calculated from pulmonary perfusion magnetic resonance imaging (MRI) and those calculated from radionuclide (RN) perfusion scintigraphy. Materials and Methods:A retrospective analysis of MR and RN perfusion scans was conducted in 23 patients (mean age, 60 ± 14 years) with different lung diseases (lung cancer = 15, chronic obstructive pulmonary disease = 4, cystic fibrosis = 2, and mesothelioma = 2). Pulmonary perfusion was assessed by a time-resolved contrast-enhanced 3D gradient-echo pulse sequence using parallel imaging and view sharing (TR = 1.9 milliseconds; TE = 0.8 milliseconds; parallel imaging acceleration factor = 2; partition thickness = 4 mm; matrix = 256 × 96; in-plane spatial resolution = 1.87 × 3.75 mm; scan time for each 3D dataset = 1.5 seconds), using gadolinium-based contrast agents (injection flow rate = 5 mL/s, dose = 0.1 mmol/kg of body weight). The peak concentration (PC) of the contrast agent bolus, the pulmonary blood flow (PBF), and blood volume (PBV) were computed from the signal-time curves of the lung. Left-to-right ratios of pulmonary perfusion were calculated from the MR parameters and RN counts. The agreement between these ratios was assessed for side prevalence (sign test) and quantitatively (Deming-regression). Results:MR and RN ratios agreed on side prevalence in 21 patients (91%) with PC, in 20 (87%) with PBF, and in 17 (74%) with PBV. The MR estimations of left-to-right perfusion ratios correlated significantly with those of RN perfusion scans (P < 0.01). The correlation was higher using PC (r = 0.67) and PBF (r = 0.66) than using PBV (r = 0.50). The MR ratios computed from PBF showed the highest accuracy, followed by those from PC and PBV. Independently from the MR parameter used, in some patients the quantitative difference between the MR and RN ratios was not negligible. Conclusions:Pulmonary perfusion MRI can be used to assess the differential blood flow of the lung. Further studies in a larger group of patients are required to fully confirm the clinical suitability of this imaging method.

Monitoring of lung motion in patients with malignant pleural mesothelioma using two-dimensional and three-dimensional dynamic magnetic resonance imaging : Comparison with spirometry

Purpose:To monitor lung motion in patients with malignant pleural mesothelioma (MPM) before and after chemotherapy (CHT) using 2-dimensional (2D) and 3-dimensional (3D) dynamic MRI (dMRI) in comparison with spirometry. Methods and Materials:Twenty-two patients with MPM were examined before CHT, as well as after 3 and 6 CHT cycles (3 months and 6 months) using 2D dMRI (trueFISP; 3 images/s) and 3D dMRI (FLASH 3D, 1 slab (52 slices)/s) using parallel imaging in combination with view-sharing technique. Maximum craniocaudal lung dimensions (2D) and lung volumes (3D) were monitored, separated into the tumor-bearing and nontumor-bearing hemithorax. Vital capacity (VC) was measured for comparison using spirometry. Results:Using 2D technique, there was a significant difference between the tumor-bearing and the nontumor-bearing hemithorax before CHT (P < 0.01) and after 3 CHT cycles (P < 0.05), whereas difference was not significant in the second control. In the tumor-bearing hemithorax, mobility increased significantly from the status before versus after 3 CHT cycles (4.1 ± 1.1 cm vs. 4.8 ± 1.4 cm, P < 0.05). Using 3D technique, at maximum inspiration, the volume of the tumor-bearing hemithorax was 0.6 ± 0.4 L and of the nontumor-bearing hemithorax 1.25 ± 0.4 L before CHT. In the follow-up exams, these volumes changed to 1.05 ± 0.4 L (P < 0.05) and 1.4 ± 0.5 L, respectively. Using spirometry, there was no significant change in VC (1.9 ± 0.4 L vs. 2.2 ± 0.7 L vs. 2.2 ± 0.9 L). Conclusion:dMRI is capable of monitoring changes in lung motion and volumetry in patients with MPM not detected by global spirometry. Thus, dMRI is proposed for use as a further measure of therapy response.

Estimation of Pulmonary Motion in Healthy Subjects and Patients with Intrathoracic Tumors Using 3D-Dynamic MRI: Initial Results

Objective To estimate a new technique for quantifying regional lung motion using 3D-MRI in healthy volunteers and to apply the technique in patients with intra- or extrapulmonary tumors. Materials and Methods Intraparenchymal lung motion during a whole breathing cycle was quantified in 30 healthy volunteers using 3D-dynamic MRI (FLASH [fast low angle shot] 3D, TRICKS [time-resolved interpolated contrast kinetics]). Qualitative and quantitative vector color maps and cumulative histograms were performed using an introduced semiautomatic algorithm. An analysis of lung motion was performed and correlated with an established 2D-MRI technique for verification. As a proof of concept, the technique was applied in five patients with non-small cell lung cancer (NSCLC) and 5 patients with malignant pleural mesothelioma (MPM). Results The correlation between intraparenchymal lung motion of the basal lung parts and the 2D-MRI technique was significant (r = 0.89, p < 0.05). Also, the vector color maps quantitatively illustrated regional lung motion in all healthy volunteers. No differences were observed between both hemithoraces, which was verified by cumulative histograms. The patients with NSCLC showed a local lack of lung motion in the area of the tumor. In the patients with MPM, there was global diminished motion of the tumor bearing hemithorax, which improved siginificantly after chemotherapy (CHT) (assessed by the 2D- and 3D-techniques) (p < 0.01). Using global spirometry, an improvement could also be shown (vital capacity 2.9 ± 0.5 versus 3.4 L ± 0.6, FEV1 0.9 ± 0.2 versus 1.4 ± 0.2 L) after CHT, but this improvement was not significant. Conclusion A 3D-dynamic MRI is able to quantify intraparenchymal lung motion. Local and global parenchymal pathologies can be precisely located and might be a new tool used to quantify even slight changes in lung motion (e.g. in therapy monitoring, follow-up studies or even benign lung diseases).

MR Angiography: clinical applications in thoracic surgery

MR angiography (MRA) is a promising completion of MR imaging in the preoperative assessment of pulmonary and mediastinal tumours. Scan acquisition was done by sequential FLASH 2D angiograms (TR = 30 ms, TE = 10 ms, FA = 30°), one section per breathhold, section thickness 5 mm with 1 mm overlap between sequential sections. An automated control procedure allowed individiual continuation of the examination. Postprocessing by a maximum-intensity-projection algorithm using angiograms of interest (AOI) resulted in 3D reconstructions illustrating vascular anatomy and avoiding superimposition. This technique was evaluated in a prospective study of 15 patients with malignant intrathoracic tumours. The results were validated by conventional angiographic procedures such as pulmonary angiography, digital subtraction angiography or cavography. Complementing spin-echo (SE) imaging, MRA provided diagnostic information about vessel displacement, stenosis and perfusion defects due to space-occupying lesions. Thus MRA was helpful in planning thoracic surgery.

Clinical applications of MR angiography in intrathoracic masses.

This is a prospective evaluation of the use of MR angiography (MRA) at 1.5 T in the assessment of intrathoracic masses. Two-dimensional (2D) MRA was obtained sequentially by means of a fast low angle shot (FLASH) technique (repetition time 30 ms, echo time 10 ms, flip angle 30 degrees) one slice per breath-holding. An automated control procedure and instantaneous image reconstruction permitted constant monitoring of the image quality and tailoring of the timing of the scans to each patients breathing capacity; MRA was successfully completed in all patients. Two-dimensional FLASH angiography was postprocessed into three-dimensional (3D) MR angiography (projections) by a maximum-intensity-projection algorithm; a 3D spatial impression of the MRA was achieved by obtaining 3D MRAs from different viewing angles and by viewing these in a cine-loop. Superimposition of vessels was avoided by creating angiograms of interest of a specific anatomic region. Fifteen patients with malignant or benign intrathoracic tumor were evaluated; their MR findings were correlated with chest radiography, conventional angiography, bolus enhanced CT, and/or perfusion scintigraphy. Magnetic resonance angiography revealed stenosis, distortion, and displacement of vessels by tumors as well as distal perfusion defects caused by proximal tumors. The MRA findings were readily accepted by our clinical colleagues and incorporated into their surgical planning. We believe MRA to be a promising complement to MR imaging in the assessment of intrathoracic masses.

Pulmonary Vein Stenosis After Radiofrequency Ablation for Atrial Fibrillation Image Findings With Multiphasic Pulmonary Magnetic Resonance Angiography

A 53-year-old man was admitted with productive cough, chest pain, and hemoptysis. Eight months earlier, he had undergone radiofrequency ablation for atrial fibrillation originating from the right upper and both left pulmonary veins. Computed tomography demonstrated bronchopneumonic infiltrates in both upper lobes (Figure 1). A perfusion scintigram, performed to exclude pulmonary embolism, showed hypoperfusion of both upper lobes, despite a normal ventilation scintigram (Figure 2). Catheter angiography …

Images in cardiovascular medicine. Pulmonary vein stenosis after radiofrequency ablation for atrial fibrillation: image findings with multiphasic pulmonary magnetic resonance angiography.

A 53-year-old man was admitted with productive cough, chest pain, and hemoptysis. Eight months earlier, he had undergone radiofrequency ablation for atrial fibrillation originating from the right upper and both left pulmonary veins. Computed tomography demonstrated bronchopneumonic infiltrates in both upper lobes (Figure 1). A perfusion scintigram, performed to exclude pulmonary embolism, showed hypoperfusion of both upper lobes, despite a normal ventilation scintigram (Figure 2). Catheter angiography …

Pulmonary Vein Stenosis After Radiofrequency Ablation for Atrial Fibrillation

A 53-year-old man was admitted with productive cough, chest pain, and hemoptysis. Eight months earlier, he had undergone radiofrequency ablation for atrial fibrillation originating from the right upper and both left pulmonary veins. Computed tomography demonstrated bronchopneumonic infiltrates in both upper lobes (Figure 1). A perfusion scintigram, performed to exclude pulmonary embolism, showed hypoperfusion of both upper lobes, despite a normal ventilation scintigram (Figure 2). Catheter angiography …