Investigative Radiology (INVEST RADIOL)

Publications in this journal

• Article: Automatic Detection, Localization and Volume Estimation of Ischemic Infarcts in Noncontrast CT Scans: Method and Preliminary Results.

  Nowinski WL, Gupta V, Qian GY, He J, Poh LE, Ambrosius W, Chrzan RM, Polonara G, Mazzoni C, Mol M, Salvolini L, Walecki J, Salvolini U, Urbanik A, Kazmierski R
  Investigative Radiology 09/2013;
• Article: Computer-Aided Detection of Colorectal Polyps in CT Colonography With and Without Fecal Tagging: A Stand-Alone Evaluation

  Thomas Mang, Luca Bogoni, Marcos Salganicoff, Matthias Wolf, Vikas Raykar, Michael Macari, Perry J. Pickhardt, Franco Iafrate, Andrea Laghi, Michael Weber, Mark E. Baker, Helmut Ringl, Christian J. Herold, Anno Graser
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  ABSTRACT: Purpose: To evaluate the stand-alone performance of a computer-aided detection (CAD) algorithm for colorectal polyps in a large heterogeneous CT colonography (CTC) database that included both tagged and untagged datasets. Methods: Written, informed consent was waived for this institutional review board-approved, HIPAA-compliant retrospective study. CTC datasets from 2063 patients were assigned to training (n = 374) and testing (n = 1689). The test set consisted of 836 untagged and 853 tagged examinations not used for CAD training. Examinations were performed at 15 sites in the United States, Asia, and Europe, using 4- to 64-multidetector-row computed tomography and various acquisition parameters. CAD sensitivities were calculated on a per-patient and per-polyp basis for polyps measuring ≥6 mm. The reference standard was colonoscopy in 1588 (94%) and consensus interpretation by expert radiologists in 101 (6%) patients. Statistical testing employed χ2, logistic regression, and Mann-Whitney U tests. Results: In 383 of 1689 individuals, 564 polyps measuring ≥6 mm were identified by the reference standard (347 polyps: 6–9 mm and 217 polyps: ≥10 mm). Overall, CAD per-patient sensitivity was 89.6% (343/383), with 89.0% (187/210) for untagged and 90.2% (156/173) for tagged datasets (P = 0.72). Overall, per-polyp sensitivity was 86.9% (490/564), with 84.4% (270/320) for untagged and 90.2% (220/244) for tagged examinations (P = 068). The mean false-positive rate per patient was 5.14 (median, 4) in untagged and 4.67 (median, 4) in tagged patient datasets (P = 0.353). Conclusion: Stand-alone CAD can be applied to both tagged and untagged CTC studies without significant performance differences. Detection rates are comparable to human readers at a relatively low false-positive rate, making CAD a useful tool in clinical practice.
  Investigative Radiology 01/2012; 47(2):99–108.
• Article: Apparent Diffusion Coefficient and Sodium Concentration Measurements in Human Prostate Tissue via Hydrogen-1 and Sodium-23 MRI in a Clinical Setting at 3T

  D. Hausmann, S. Wetterling, S. Haneder, A. Nagel, D. Dinter, S. Schoenberg, F. Zöllner, L. Schad
  Investigative Radiology 01/2012;
• Article: The First Analysis and Clinical Evaluation of Native Breast Tissue Using Differential Phase-Contrast Mammography

  Marco Stampanoni, Zhentian Wang, Thomas Thüring, Christian David, Ewald Roessl, Mafalda Trippel, Rahel A. Kubik-Huch, Gad Singer, Michael K. Hohl, Nik Hauser
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  ABSTRACT: Objectives: Phase-contrast and scattering-based x-ray imaging are known to provide additional and complementary information to conventional, absorption-based methods, and therefore have the potential to play a crucial role in medical diagnostics. We report on the first mammographic investigation of 5 native, that is, freshly dissected, breasts carried out with a grating interferometer and a conventional x-ray tube source. Four patients in this study had histopathologically proven invasive breast cancer. One male patient, without the presence of any malignant formations within the resected breast, was included as a control specimen. Materials and Methods: We used a Talbot-Lau grating setup installed on a conventional, low-brilliance x-ray source; the interferometer operated at the fifth Talbot distance, at a tube voltage of 40 kVp with mean energy of 28 keV, and at a current of 25 mA. The device simultaneously recorded absorption, differential phase and small-angle scattering signals from the native breast tissue. These quantities were then combined into novel color- and high-frequency-enhanced radiographic images. Presurgical images (conventional mammography, ultrasonography, and magnetic resonance imaging) supported the findings and clinical relevance was verified. Results: Our approach yields complementary and otherwise inaccessible information on the electron density distribution and the small-angle scattering power of the sample at the microscopic scale. This information can be used to potentially answer clinically relevant, yet unresolved questions such as unequivocally discerning between malignant and premalignant changes and postoperative scars and distinguishing cancer-invaded regions within healthy tissue. Conclusions: We present the first ex vivo images of fresh, native breast tissue obtained from mastectomy specimens using grating interferometry. This technique yields improved diagnostic capabilities when compared with conventional mammography, especially when discerning the type of malignant conversions and their breadth within normal breast tissue. These promising results advance us toward the ultimate goal, using grating interferometry in vivo on humans in a clinical setting.
  Investigative Radiology 11/2011; 46(12):801–806.
• Article: Consensus Report of the Third International Forum for Liver Magnetic Resonance Imaging

  Luigi Grazioli, Jeong Min Lee, Peter Malfertheiner, Christoph J. Zech, Lennart Blomqvist, Elmar M. Merkle
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  ABSTRACT: This consensus report arises from the discussions at the Third International Forum for Liver Magnetic Resonance Imaging, at which attendees evaluated the use of the hepatocyte-specific contrast agent gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA, Primovist, Bayer Schering Pharma, Berlin, Germany; Eovist, Bayer HealthCare Pharmaceuticals Inc., Wayne, NJ; EOB-Primovist, Bayer Schering Pharma, Osaka, Japan). The impact of Gd-EOB-DTPA uptake by hepatocytes on the enhancement pattern, compared with dynamic imaging with extracellular contrast media, and its value in diagnostic confidence were discussed. Although the dynamic-phase images of typical cavernous hemangiomas are comparable using Gd-EOB-DTPA and gadolinium-based extracellular contrast media, such lesions appear hypointense during the hepatobiliary phase with Gd-EOB-DTPA. The rapid uptake of Gd-EOB-DTPA by hepatocytes results in lesions of hepatocellular origin already appearing hyperintense during the late-dynamic-phase imaging. Focal nodular hyperplasia can be detected with confidence using Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI). Currently, information on the appearance of the Gd-EOB-DTPA-enhanced images of hepatic adenomas in the hepatobiliary phase is limited. Published data support the use of Gd-EOB-DTPA-enhanced MRI for diagnosis of liver metastases. However, some diagnostic algorithms do not address recent advances in imaging technology and fail to recognize the role of Gd-EOB-DTPA in the detection of hepatocellular carcinoma and its ability to distinguish between benign and malignant lesions. Beyond its approved use for the detection and characterization of liver lesions in adults with known or suspected focal liver disease, Gd-EOB-DTPA has the potential to be used in the assessment of liver function and the examination of the biliary system.
  Investigative Radiology 11/2010; 45(12):S1-S10.
• Article: Thoracoabdominal-Aortoiliac Multidetector-Row CT Angiography at 80 and 100 kVp: Assessment of Image Quality and Radiation Dose

  Sebastian T. Schindera, Patricia Graca, Michael A. Patak, Susanne Abderhalden, Gabriel von Allmen, Peter Vock, Zsolt Szucs-Farkas
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  ABSTRACT: Objective: To compare image quality and radiation dose of thoracoabdominal computed tomography (CT) angiography at 80 and 100 kVp and to assess the feasibility of reducing contrast medium volume from 60 to 45 mL at 80 kVp. Materials and Methods: This retrospective study had institutional review board approval; informed consent was waived. Seventy-five patients who had undergone thoracoabdominal 64-section multidetector-row CT angiography were divided into 3 groups of 25 patients each. Patients of groups A (tube voltage, 100 kVp) and B (tube voltage, 80 kVp) received 60 mL of contrast medium at 4 mL/s. Patients of group C (tube voltage, 80 kVp) received 45 mL of contrast medium at 3 mL/s. Mean aortoiliac attenuation, image noise, and contrast-to-noise ratio were assessed. The measurement of radiation dose was based on the volume CT dose index. Three independent readers assessed the diagnostic image quality. Results: Mean aortoiliac attenuation for group B (621.1 ± 90.5 HU) was significantly greater than for groups A and C (485.2 ± 110.5 HU and 483.1 ± 119.8 HU; respectively) (P < 0.001). Mean image noise was significantly higher for groups B and C than for group A (P < 0.05). The contrast-to-noise ratio did not significantly differ between the groups (group A, 35.0 ± 13.8; group B, 31.7 ± 10.1; group C, 27.3 ± 11.5; P = 0.08). Mean volume CT dose index in groups B and C (5.2 ± 0.4 mGy and 4.9 ± 0.3 mGy, respectively) were reduced by 23.5% and 27.9%, respectively, compared with group A (6.8 ± 0.8 mGy) (P < 0.001). The average overall diagnostic image quality for the 3 groups was graded as good or better. The score for group A was significantly higher than that for group C (P < 0.01), no difference was seen between group A and B (P = 0.92). Conclusions: Reduction of tube voltage from 100 to 80 kVp for thoracoabdominal CT angiography significantly reduces radiation dose without compromising image quality. Reduction of contrast medium volume to 45 mL at 80 kVp resulted in lower but still diagnostically acceptable image quality.
  Investigative Radiology 09/2009; 44(10):650-655.
• Article: A Comparison of 3T and 7T in the Detection of Small Parenchymal Veins Within MS Lesions

  Emma C. Tallantyre, Paul S. Morgan, Jennifer E. Dixon, Ali Al-Radaideh, Matthew J. Brookes, Nikos Evangelou, Peter G. Morris
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  ABSTRACT: Objective: Histologic examination of multiple sclerosis (MS) brain lesions reveals heterogeneity including the presence or absence of a central blood vessel. Recent work has shown that T2* weighted magnetic resonance imaging at 7T allows the identification of small parenchymal veins within MS lesions. The aims of this study were (1) to compare whether a comparable sequence at 3T was also capable of demonstrating parenchymal veins within MS brain lesions, and (2) to investigate the potential of 7T T2* weighted imaging to differentiate between MS white matter lesions and age-related vascular lesions seen in controls. Materials and Methods: Seven patients with demyelinating brain disease and 7 healthy volunteers were scanned at 3T and 7T. Fluid attenuated inversion recovery (FLAIR) images acquired at 3T were used to identify each brain lesion in each patient. A comparison of images from both field strengths was then made to determine whether white matter lesions seen in 3T FLAIR images could be identified in T2*-weighted images, and whether a central vein could be detected. Results: A total of 358 brain lesions were identified in the brains of the 7 patients using 3T FLAIR images. The 3T T2* sequence detected 89% of FLAIR lesions compared with 94% using the 7T T2* sequence (P = 0.0002). A central vessel could be identified in 45% of visible lesions using 3T T2* and 87% of visible lesions using 7T T2* (P < 0.0001). Using 7T T2* imaging, a central vein was evident in only 8% of the discrete white matter lesions found in the brains of healthy volunteers. Discussion: This study suggests that ultra high field imaging is advantageous in demonstrating detailed structural anatomy of MS lesions. 7T T2* imaging can be used in the future to investigate the pathogenesis of MS lesions. The potential for ultra high field imaging to discriminate between MS white matter lesions and microangiopathic lesions warrants further investigation as this would represent a clinically useful application.
  Investigative Radiology 08/2009; 44(9):491-494.
• Article: Computed tomography perfusion using first pass methods for lung nodule characterization: limits and implications in radiologic practice.

  Volterrani L, Mazzei MA, Fedi M, Scialpi M
  Investigative Radiology 02/2009;
• Article: Efficacy of Computer-Aided Detection System and Thin-Slab Maximum Intensity Projection Technique in the Detection of Pulmonary Nodules in Patients With Resected Metastases

  Eun-Ah Park, Jin Mo Goo, Jeong Won Lee, Chang Hyun Kang, Hyun Ju Lee, Chang Hyun Lee, Chang Min Park, Ho Yun Lee, Jung-Gi Im
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  ABSTRACT: Objectives: To evaluate the efficacy of the computer-aided detection (CAD) system and thin-slab maximum intensity projection (MIP) technique in the detection of pulmonary nodules at multidetector computed tomography (CT) in patients who underwent metastatectomy. Materials and Methods: This retrospective study was approved by the institutional review board and patients' informed consent was waived. Forty-nine consecutive patients who underwent pulmonary metastatectomy were enrolled. Four chest radiologists analyzed preoperative 1-mm section CT images and recorded the locus of each nodule candidate. Afterward, they reevaluated the images once using CAD software and once with thin-slab MIP given the results of 1-mm section CT alone. The reference standard for nodule presence was established by a consensus panel and pathologic records for malignant nodules. Results: A total of 514 nodules were identified by a consensus panel. Of 212 nodules surgically removed, 121 nodules were malignant. The sensitivity of each observer in detecting malignant nodules with thin-section CT scans alone was 91%, 88%, 87%, and 86% for observers A- to D, respectively. With CAD, sensitivity increased significantly to 95%, 95%, 94%, and 95% (P< 0.05 for observer B-D), and using MIP increased to 94%, 96%, 91%, and 92% (P < 0.05 for observer B-D), respectively. There were no significant differences in sensitivity between CAD and MIP for the detection of malignant nodules. The average number of false-positive findings per patient was 0.8 with thin-section CT alone, 1.1 with CAD, and 1.4 with MIP. Conclusions: In candidates for metastatectomy, reading with the aid of either CAD or MIP significantly improved the detection of malignant nodules compared with using thin-section CT alone.
  Investigative Radiology 01/2009; 44(2):105-113.
• Article: Quantification of lung volume at different tidal volumes and positive end-expiratory pressures in a porcine model by using retrospective respiratory gated 4D-computed tomography.

  Julia Ley-Zaporozhan, Sebastian Ley, Roland Unterhinninghofen, Oliver Weinheimer, Yasuo Saito, Hans-Ulrich Kauczor, Gabor Szabo
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  ABSTRACT: This feasibility study in healthy animals should prove the concept that it is possible to quantitatively assess the effects of different ventilatory settings on the lung parenchyma during ongoing ventilation in respiratory gated 4-dimensional (D)-computed tomography (CT). For this purpose, the influence of different tidal volumes and positive end-expiratory pressure (PEEP) on quantitative assessment of lung volumes (LVs) and lung compartments was analyzed. Five anesthetized and ventilated (20 breaths/min, inspiratory/expiratory ratio of 1:2) healthy pigs underwent 16-row multidetector CT with retrospective respiratory gating using a noncontact charge-coupled device camera as a gating device. The device was connected to the scanner instead of the electrocardiogram gating unit. Parameters for retrospective scans were collimation 1 mm, 120 kV, 300 mA, gantry rotation time 0.5 seconds, helical pitch 2.4. Two tidal volumes (300 mL and 450 mL) and 3 PEEP levels (0, 5, and 10 cm H(2)O) were applied resulting in 6 scans per animal. Images were reconstructed throughout the respiratory cycle in increments of 10%. Semiautomatic segmentation provided LV, mean lung density (MLD), and different lung compartments (atelectasis, hypoventilated, normal ventilated, hyperventilated). At tidal volume 300 mL the inspiratory LV were 1.05, 1.26, and 1.5 L and expiratory LV 0.75, 0.99, and 1.24 L (PEEP 0, 5, 10 cm H(2)O, respectively). Differences of MLD between inspiration and expiration were 86, 65, and 46 HU. At tidal volume 450 mL, the inspiratory LV were 1.21, 1.43, and 1.72 L, and expiratory LV were 0.78, 1.01, and 1.34 L (for PEEP 0, 5, 10 cm H(2)O). Differences of MLD between inspiration and expiration were 109, 86, and 59 HU. A clear oscillatory wave of the normal and hypoventilated volumes was found at PEEP 0, with increase in PEEP the hypoventilated areas became increasingly normal ventilated, the amplitude of the curves decreased, and hyperventilated areas increased. Using a new 4D-CT technique we were able to demonstrate the effect of different ventilation settings on the whole lung during the whole respiratory cycle. The disadvantages of static lung imaging or dynamic 2D-CT can be overcome. The possibility of quantitative evaluation of the whole lung and direct visualization and measurement of recruitment during different ventilation settings might be a great benefit for patients suffering from inhomogeneous lung injury and failure.
  Investigative Radiology 07/2008; 43(6):461-9.
• Article: Detection of pulmonary nodules with move-during-scan magnetic resonance imaging using a free-breathing turbo inversion recovery magnitude sequence.

  Tobias Baumann, Ute Ludwig, Gregor Pache, Christine Gall, Ulrich Saueressig, Dagmar Fisch, Zoran Stankovic, Jean-Paul Bartholomae, Matthias Honal, Thorsten Alexander Bley, Mathias Langer, Oliver Schaefer
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  ABSTRACT: Detection of pulmonary metastases is still a challenging task for magnetic resonance imaging (MRI). It was the aim of this study to evaluate the potential of a free-breathing move-during-scan turbo inversion recovery magnitude sequence for the detection of pulmonary nodules. The sensitivities and positive-predictive values of 2 radiologists to detect pulmonary nodules in 41 move-during-scan MRI examinations of 38 patients with different malignancies were calculated and subgroup analyses according to lesion size and localization were performed. Multidetector computed tomography served as the standard of reference. Additionally, 6 radiologists rated the confidence for the presence of nodular lesions in 212 regions-of-interest, which were randomly selected to represent lesions of various sizes as well as negative findings. Receiver-operator-characteristic was performed. Three hundred twenty-one nodules were found in 30 patients by multidetector computed tomography. Sensitivity and specificity of MRI to detect pulmonary nodules larger than 3 mm on a per-patient basis were 81.8% and 94.7%, respectively. On a per-lesion basis, MRI revealed a sensitivity of 79.0% to 80.7% for lesions larger than 3 mm, if high conspicuity ratings were counted as positive, and 84.6%, if medium and high conspicuity ratings were counted as positive. Sensitivity increased uniformly with lesion size, and all lesions larger than 12 mm were detected. Receiver-operator-characteristic analysis revealed a mean accuracy of 0.90 and sensitivities over 90% for lesions larger than 3 mm with a specificity of 96.1%. For lesions larger than 6 mm the accuracy was 0.99. Detection of pulmonary nodules with a move-during-scan turbo inversion recovery magnitude sequence is feasible. Excellent detection of lesions larger than 6 mm is achievable with free-breathing moving-table MRI.
  Investigative Radiology 07/2008; 43(6):359-67.
• Article: Lung perfusion in patients with pulmonary hypertension: comparison between MDCT pulmonary angiography with minIP reconstructions and 99mTc-MAA perfusion scan.

  Tommaso Bartalena, Devil Oboldi, Pier Luigi Guidalotti, Maria Francesca Rinaldi, Paola Bertaccini, Gabriella Napoli, Giampaolo Gavelli
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  ABSTRACT: Alterations in lung perfusion are a well-known feature of pulmonary hypertension (PH) seen on nuclear medicine studies. Abnormal radiotracer distribution in patients with PH may be caused by arterial thromboembolic occlusion, like in chronic thromboembolic pulmonary hypertension, by parenchymal destruction as in interstitial lung disease and pulmonary emphysema or by distal arteriopathy, like in idiopathic pulmonary arterial hypertension and other nonembolic forms. The different imaging pattern on radionuclide perfusion studies represents an important element for differential diagnosis. The aim of this study was to evaluate minimum intensity projection (minIP) images as an alternative to perfusion scintigraphy. We compared lung parenchyma attenuation patterns as depicted in minIP reconstructions with scintigraphic findings of lung perfusion in patients affected by pulmonary hypertension from various etiologies. One hundred and seven consecutive patients affected by PH of different etiology (37 of those had chronic thromboembolic pulmonary hypertension) who had undergone both multidetector computed tomography pulmonary angiography and 99mTc-MAA perfusion scan were included. Five-millimeter thickness contiguous axial, coronal, and sagittal minIP images were reconstructed from the contrast enhanced computed tomography datasets. Two radiologists evaluated the images and qualitatively graded pulmonary attenuation as homogeneous, inhomogeneous with nonsegmental patchy defects, or inhomogeneous with segmental defects. The presence of parenchymal and pleural alterations was recorded. MinIP perfusion grading results were then compared with those of perfusion scintigraphy. In 87 of 107 patients (81.3%), the attenuation pattern seen on minIP images (39 homogeneous patterns, 13 with nonsegmental patchy defects, and 39 with segmental defects) correlated with the nuclear medicine scans. In the remaining 20 patients (18.7%), the imaging pattern was discordant because of 7 false-positive and 2 false-negative thromboembolic patterns at minIP and 11 false-positive thromboembolic patterns at perfusion scan. Air-trapping and parenchymal disease caused false-positive findings at minIP and perfusion scans, respectively. The sensitivity and specificity of minIP in detection of a chronic thromboembolic perfusion pattern were 94.5% and 90%, whereas perfusion scan had 100% sensitivity and 84% specificity. MinIP reconstructions can identify different patterns of pulmonary parenchymal attenuation, which show high concordance with perfusion patterns seen on radionuclide studies in patients with pulmonary hypertension. MinIP is a promising technique to evaluate lung perfusion in PH and may be used as an alternative to scintigraphy in the diagnostic work-up of these patients.
  Investigative Radiology 07/2008; 43(6):368-73.
• Article: Texture-based quantification of pulmonary emphysema on high-resolution computed tomography: comparison with density-based quantification and correlation with pulmonary function test.

  Yang Shin Park, Joon Beom Seo, Namkug Kim, Eun Jin Chae, Yeon Mok Oh, Sang Do Lee, Youngjoo Lee, Suk-Ho Kang
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  ABSTRACT: To develop a system for texture-based quantification of emphysema on high-resolution computed tomography (HRCT) and to compare it with density-based quantification in correlation with pulmonary function test (PFT). Two hundred sixty-one circular regions of interest (ROI) with 16-pixel diameter [66 ROIs representing typical area of normal lung; 69 representing bronchiolitis obliterans (BO); 64, mild emphysema (ME); and 62, severe emphysema (SE)] were used to train the automated classification system based on the Support Vector Machine classifier and on variable texture and shape features. An automated quantification system was developed with a moving ROI in the lung area, which classified each pixel into 4 categories. To validate the system, the HRCT and standard-kernel-reconstructed volumetric CT data of 39 consecutive patients with emphysema were included. Using this system, the whole lung area was evaluated, and the area fractions of each class were calculated (normal lung%, BO%, ME%, SE%, respectively). The emphysema index (EI) of texture-based quantification was defined as follows: (0.3 x ME% + SE%) (TEI). EIs from density-based quantification with a threshold of -950 Hounsfield Units, were measured on both HRCT (DEI_HR_2D) and on volumetric CT (DEI_standard_3D). The agreement between TEI, DEI_HR_2D, and DEI_standard_3D was assessed using interclass correlation coefficients (ICC). Correlation of the results on the TEI with the PFT results was compared with the results of the DEI_standard_3D and the DEI_HR_2D with Spearman's correlation test. To evaluate the contribution of each texture-based quantification lesion (BO%, ME%, SE%) on PFT, multiple linear regression analysis was performed. The calculated TEI (19.71% +/- 17.98%) was well correlated with the DEI_standard_3D (19.42% +/- 14.30%) (ICC = 0.95), whereas the ICC with DEI_HR_2D (37.22% +/- 9.42%) was 0.43. TEI showed better correlation with PFT than DEI_standard_3D or DEI_HR_2D did [R = 0.71 vs. 0.67 vs. 0.61 for forced expiratory volume in 1 second (FEV(1))/forced vital capacity (FVC); 0.54 vs. 0.50 vs. 0.43 for diffusing capacity (DLco), respectively]. Multiple linear regression analysis revealed that the BO% and SE% areas were independent determinants of FEV(1)/FVC, whereas the ME% and the SE% were determinants of DLco. Texture-based quantification of emphysema using an automated system showed better correlation with the PFT results than density-based quantification. Separate quantification of the BO, ME, and SE areas showed a different contribution of each component to the FEV(1)/FVC and the DLco. The proposed system can be successfully used for detailed regional and global evaluation of lung lesions on HRCT scanning for emphysema.
  Investigative Radiology 07/2008; 43(6):395-402.
• Article: Comparison of radiologist and CAD performance in the detection of CT-confirmed subtle pulmonary nodules on digital chest radiographs.

  Thorsten Alexander Bley, Tobias Baumann, Ulrich Saueressig, Gregor Pache, Markus Treier, Oliver Schaefer, Ulrich Neitzel, Mathias Langer, Elmar Kotter
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  ABSTRACT: Detection of subtle pulmonary nodules on digital radiography is a challenging task for radiologists. The aim of this study was to evaluate the performance of a newly approved computer aided detection (CAD) system. The sensitivity of 3 radiologists and of a CAD system for the detection of pulmonary nodules from 5 to 15 mm in size on digital chest radiography of 117 patients was compared. The reference standard was established by consensus reading of computed tomography scans by 2 experienced radiologists. Computed tomography scans and chest radiographs were performed within 4 weeks. Sixty-six pulmonary nodules from 42 patients, with a mean nodule diameter of 7.5 mm (standard deviation: 2.2 mm), were included in the statistical analysis. Seventy-five of the 117 patients did not have nodules from 5 to 15 mm of size. Two hundred and eighty-eight false-positive detections of the CAD system were found with an average of 2.5 false-positives per image. Sensitivity of the CAD system was 39.4% (95% confidence interval: 11.8%), when compared with 18.2% to 30.3% (95% confidence interval 9.3% to 11.1%) of the 3 radiologists. Substantial agreement for nodule detection ([kappa]N: 0.64-0.73) was found among the 3 radiologists, whereas only moderate agreement was found between the radiologists and the CAD performance ([kappa]N: 0.45-0.52). The CAD system's diagnostic sensitivity in detecting pulmonary nodules of 5 to 15 mm of size was superior to the 1 of radiologists. The CAD system may be used for assisting the radiologist in the detection of lung nodules on digital chest radiographs.
  Investigative Radiology 07/2008; 43(6):343-8.
• Article: Validation of magnetic resonance phase-contrast flow measurements in the main pulmonary artery and aorta using perivascular ultrasound in a large animal model.

  Sebastian Ley, Roland Unterhinninghofen, Julia Ley-Zaporozhan, Jens-Peter Schenk, Hans-Ulrich Kauczor, Gabor Szabo
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  ABSTRACT: Phase-contrast flow magnetic resonance imaging (pc-MRI) measurements are an established technique for noninvasive assessment of hemodynamics. However, in vivo validation data on the accuracy of pc-flow especially for nonphysiologic hemodynamic conditions are missing. The goal of our work was 1) to validate pc-flow with perivascular ultrasound in different hemodynamic conditions in the main pulmonary artery (MPA) and ascending aorta (AO) and 2) to investigate the relation between pc-MRI and invasive pressure measurements. Five healthy pigs with opened chest were investigated. Ultrasound measurements were performed outside the MRI unit using a detachable MR-table. Parallel to ultrasound flow measurements, invasive pressure measurements were performed. PC-MRI (1.5 T MRI) measurements were done using a FLASH 2-dimensional sequence. First the animals were examined in normotonia, followed by hypertension (infusion of Arterenol) and hypotension (infusion of Sodiumnitropussid). Flow measurements acquired in normotonia were 2.7 +/- 0.6 L/min (ultrasound) and 2.8 +/- 0.6 L/min for pc-MRI (not significantly different, P = 0.17). During hypertonia, the blood flow increased to 3.1 +/- 0.7 and 2.7 +/- 0.8 L/min, respectively (P = 0.01). During hypotension, the blood flow decreased to 1.7 +/- 0.5 and 1.7 +/- 0.5 L/min, respectively (P = 0.7). An excellent linear correlation (taking all measurements together) between the ultrasound and pc-MRI measurements was found (r = 0.89). 95% Limits of intraindividual agreement correspond to relative differences of -36 to 44%. Systolic pressure measurements in the AO were 91 mm Hg (normotonic), 111 mm Hg (hypertonic), and 64 mm Hg (hypotonic) and in the MPA 23 mm Hg (normotonic), 29 mm Hg (hypertonic), and 20 mm Hg (hypotonic). Systolic pressure measurements showed good linear correlation with pc-MRI average flow per minute and peak velocity (AO: r = 0.79, MPA: r = 0.66). MRI pc-flow measurements are a reliable tool for noninvasive assessment of blood flow. Hemodynamic parameters derived by MRI demonstrate good linear correlations with the pressure in the systemic and pulmonary arterial circulation.
  Investigative Radiology 07/2008; 43(6):421-6.
• Article: Intrapulmonary 3He gas distribution depending on bolus size and temporal bolus placement.

  Klaus Kurt Gast, Kristin Hawig, Michael Windirsch, Klaus Markstaller, Wolfgang Günter Schreiber, Jörg Schmiedeskamp, Christoph Düber, Hans-Ulrich Kauczor, Claus Peter Heussel
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  ABSTRACT: Dynamic ventilation (3)He-MRI is a new method to assess pulmonary gas inflow. As differing airway diameters throughout the ventilatory cycle can influence gas inflow this study intends to investigate the influence of volume and timing of a He gas bolus with respect to the beginning of the tidal volume on inspiratory gas distribution. An ultrafast 2-dimensional spoiled gradient echo sequence (temporal resolution 100 milliseconds) was used for dynamic ventilation (3)He-MRI of 11 anesthetized and mechanically ventilated pigs. The applied (3)He gas bolus was varied in volume between 100 and 200 mL. A 150-mL bolus was varied in its application time after the beginning of the tidal volume between 0 and 1200 milliseconds. Signal kinetics were evaluated using an in-house developed software after definition of parameters for the quantitative description of (3)He gas inflow. The signal rise time (time interval between signal in the parenchyma reaches 10% and 90% of its maximum) was prolonged with increasing bolus volume. The parameter was shortened with increasing delay of (3)He application after the beginning of the tidal volume. Timing variation as well as volume variation showed no clear interrelation to the signal delay time 10 (time interval between signal in the trachea reaches 50% of its maximum and signal in the parenchyma reaches 10% of its maximum). Dynamic ventilation (3)He-MRI is able to detect differences in bolus geometry performed by volume variation. Pulmonary gas inflow as investigated by dynamic ventilation (3)He-MRI tends to be accelerated by an increasing application delay of a (3)He gas bolus after the beginning of the tidal volume.
  Investigative Radiology 07/2008; 43(6):439-46.
• Article: Magnetic resonance imaging spatial and time study of lung water content in newborn lamb: methods and preliminary results.

  Romain Viard, Pierre Tourneux, Laurent Storme, Julie-Marie Girard, Nacim Betrouni, Jean Rousseau
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  ABSTRACT: To study the lung liquid clearance in vivo at the time of birth, magnetic resonance experiments were conducted on newborn lambs immediately after uterine incision deliverance. Images obtained with a fast spin echo magnetic resonance imaging sequence enable to quantify lung liquid each 5 minutes for 30 minutes, then each 10 minutes for 1.5 hours. After manually determining lung contours, pulmonary volume, pulmonary water, and spatial gradient of pulmonary water were studied. At 2 hours of life, the total pulmonary water content was still high and the liquid clearance was slower in the lower part of the lung. Air inflation increased the size of the distal airways and shifted liquid from the lung lumen towards the pulmonary interstitial tissue. The lung liquid washout was belated, and the passage to the aerial life was performed by progressive liberation of the superior pulmonary spaces, water flowing out by gravity toward the lower spaces.
  Investigative Radiology 07/2008; 43(6):470-80.
• Article: Three-dimensional selective-scale texture analysis of computed tomography pulmonary angiograms.

  Balaji Ganeshan, Kenneth A Miles, Rupert C D Young, Chris R Chatwin
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  ABSTRACT: This feasibility study aims to develop 3-dimensional (3D) selective-scale texture analysis of computed tomography pulmonary angiography to identify texture correlates for ventilated and vascular lung for visual and quantitative assessment of pulmonary disorders with altered vasculature. Computed tomography pulmonary angiography examinations of 8 patients were considered in this study; 3 had normal lungs, 3 had pulmonary embolism (PE1, PE2, and PE3), 1 had only emphysema (PEmp), whereas the final patient had both emphysema and embolism (PEE). Before texture analysis, an initial automated segmentation procedure to include only the lung parenchyma and generation of isometric volume were carried out. From this segmented volume, ventilated lung and pulmonary vessels were separately selected. Texture analysis comprised 2 stages: 1) volume filtration using 3D Laplacian of Gaussian filter to highlight fine and coarse textures within ventilated and vascular lung, followed by 2) quantification of texture using mean gray-level intensity, entropy and uniformity both globally and at 3 anatomic sections of the lung, ie, anterior, middle, and posterior. Quantification of texture was also performed on the unfiltered computed tomography lung dataset. Volume rendering and image fusion of ventilated and vascular lung texture were employed for visualization. For fine texture quantified as mean gray-level intensity in ventilated lung, a postural gradient compatible with known pulmonary physiology was demonstrated and texture was different in emphysematous lung (PEmp and PEE) when compared with nonemphysematous lung (normals, PE1, PE2, and PE3) consistent with altered ventilation. Coarse texture in vascular lung demonstrated a descending trend in entropy (or ascending trend in uniformity) for normals, followed by embolism only (PE1, PE2, and PE3) and finally for emphysematous lung (PEmp and PEE) suggesting a correlation with degree of vascularity (or perfusion). 3D images of ventilated and vascular lung texture highlighted mismatched and matched defects in patients with pulmonary disorders. This feasibility study demonstrated that 3D filtered texture analysis can potentially provide correlates for ventilated and vascular lung, which may be useful in the diagnosis of PE in the presence of other causes of altered vascularity.
  Investigative Radiology 07/2008; 43(6):382-94.
• Article: Oxygen-enhanced magnetic resonance imaging: influence of different gas delivery methods on the T1-changes of the lungs.

  Francesco Molinari, Michael Puderbach, Monika Eichinger, Sebastian Ley, Christian Fink, Lorenzo Bonomo, Hans-Ulrich Kauczor, Michael Bock
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  ABSTRACT: The clinical feasibility of oxygen-enhanced magnetic resonance imaging (MRI) of the lung may benefit from the use of a simple gas delivery method. In this study, the oxygen-induced T1 change of the lung obtained using a closed O(2) delivery system was compared with that obtained by a conventional nontight face mask. Twenty-three healthy subjects (15 men, 8 women, mean age = 25 years, age range = 20-35 years) underwent oxygen-enhanced MRI of the lung using a closed O(2) delivery system composed by a tightly fitting face mask and a 60-L reservoir bag (equipment type A: n = 13, 9 men, 4 women, mean age = 24.4 years, age range = 20-32 years), or a clinically available nontight face mask (equipment type B: n = 10; 6 men, 4 women, mean age = 25.8 years, age range = 20-35 years). The effect of 100%-oxygen inhalation was assessed using a Snapshot FLASH T1-mapping technique (repetition time/echo time = 1.5-1.6/0.56 milliseconds; matrix = 128 x 90; acquisition time = 3.3-3.7 seconds; slice thickness = 15-20 mm; number of images = 40). By nonlinear curve fitting, the mean T1 values of the left and right lung at room air and 100%-oxygen ventilation were calculated (T1(room air, right); T1(oxygen, right); T1(room air, left); T1(oxygen, left)). The average T1 differences (DeltaT1 = T1(room air) - T1(oxygen)) of the 2 volunteer groups were compared (Wilcoxon signed rank test, Mann-Whitney U test). The mean T1 values obtained using the 2 respiratory equipments at room air or oxygen ventilation were not significantly different (A vs. B at room air ventilation: P = 0.85 for the right lung, P = 0.27 for the left lung; A vs. B at oxygen ventilation: P = 0.55 for the left lung, P = 0.29 for the right lung). With both systems, the mean T1 values decreased significantly after oxygen inhalation (P = 0.03-0.0002). For both lungs, the DeltaT1 obtained using the equipment type A was statistically equivalent to that obtained using the equipment type B: DeltaT1A, right = 96 +/- 19 milliseconds versus DeltaT1B, right = 97 +/- 34 milliseconds (P = 0.82); DeltaT1A, left = 74 +/- 47 milliseconds versus DeltaT1B, left = 68 +/- 63 milliseconds (P = 0.85). Gas delivery in oxygen-enhanced MRI of the lung can be performed with a clinically available standard face mask, without the need for closed sophisticated equipments.
  Investigative Radiology 07/2008; 43(6):427-32.