CT perfusion imaging of lung cancer: benefit of motion correction for blood flow estimates.

PURPOSE: CT perfusion (CTP) imaging assessment of treatment response in advanced lung cancer can be compromised by respiratory motion. Our purpose was to determine whether an original motion correction method could improve the reproducibility of such measurements. MATERIALS AND METHODS: The institutional review board approved this prospective study. Twenty-one adult patients with non-resectable non-small-cell lung cancer provided written informed consent to undergo CTP imaging. A motion correction method that consisted of manually outlining the tumor margins and then applying a rigid manual landmark registration algorithm followed by the non-rigid diffeomorphic demons algorithm was applied. The non-motion-corrected and motion-corrected images were analyzed with dual blood supply perfusion analysis software. Two observers performed the analysis twice, and the intra- and inter-observer variability of each method was assessed with Bland-Altman statistics. RESULTS: The 95% limits of agreement of intra-observer reproducibility for observer 1 improved from -84.4%, 65.3% before motion correction to -33.8%, 30.3% after motion correction (r = 0.86 and 0.97, before and after motion correction, p < 0.0001 for both) and for observer 2 from -151%, 96% to -49 %, 36 % (r = 0.87 and 0.95, p < 0.0001 for both). The 95% limits of agreement of inter-observer reproducibility improved from -168%, 154% to -17%, 25%. CONCLUSION: The use of a motion correction method significantly improves the reproducibility of CTP estimates of tumor blood flow in lung cancer. KEY POINTS: • Tumor blood flow estimates in advanced lung cancer show significant variability. • Motion correction improves the reproducibility of CT blood flow estimates in advanced lung cancer. • Reproducibility of blood flow measurements is critical to characterize lung tumor biology and the success of treatment in lung cancer.

Uncommon Causes of Interlobular Septal Thickening on CT Images and Their Distinguishing Features.

Interlobular septa thickening (ILST) is a common and easily recognized feature on computed tomography (CT) images in many lung disorders. ILST thickening can be smooth (most common), nodular, or irregular. Smooth ILST can be seen in pulmonary edema, pulmonary alveolar proteinosis, and lymphangitic spread of tumors. Nodular ILST can be seen in the lymphangitic spread of tumors, sarcoidosis, and silicosis. Irregular ILST is a finding suggestive of interstitial fibrosis, which is a common finding in fibrotic lung diseases, including sarcoidosis and usual interstitial pneumonia. Pulmonary edema and lymphangitic spread of tumors are the commonly encountered causes of ILST. It is important to narrow down the differential diagnosis as much as possible by assessing the appearance and distribution of ILST, as well as other pulmonary and extrapulmonary findings. This review will focus on the CT characterization of the secondary pulmonary lobule and ILST. Various uncommon causes of ILST will be discussed, including infections, interstitial pneumonia, depositional/infiltrative conditions, inhalational disorders, malignancies, congenital/inherited conditions, and iatrogenic causes. Awareness of the imaging appearance and various causes of ILST allows for a systematic approach, which is important for a timely diagnosis. This study highlights the importance of a structured approach to CT scan analysis that considers ILST characteristics, associated findings, and differential diagnostic considerations to facilitate accurate diagnoses.

CT-based pleural effusion volume estimation formula demonstrates low accuracy and reproducibility for traumatic hemothorax.

PURPOSE: We aimed to evaluate the accuracy and reproducibility of the CT-based volume estimation formula V = d2 * h, where d and h represent the maximum depth and height of the effusion, for acute traumatic hemothorax. MATERIALS & METHODS: Prospectively identified patients with CT showing acute traumatic hemothorax were considered. Volumes were retrospectively estimated using d2 * h, then manually measured on axial images. Subgroup analysis was performed on borderline-sized hemothorax (200-400 mL). Measurements were repeated by three non-radiologists. Bland-Altman analysis was used to assess agreement between the two methods and agreement between raters for each method. RESULTS: A total of 46 patients (median age 34; 36 men) with hemothorax volume 23-1622 mL (median 191 mL, IQR 99-324 mL) were evaluated. Limits of agreement between estimates and measured volumes were -718 - +842 mL (± 202 mL). Borderline-sized hemothorax (n = 13) limits of agreement were -300 - +121 mL (± 114 mL). Of all hemothorax, 85 % (n = 39/46) were correctly stratified as over or under 300 mL, and of borderline-sized hemothorax, 54 % (n = 7/13). Inter-rater limits of agreement were -251 - +350, -694 - +1019, and -696 - +957 for the estimation formula, respectively, and -124 - +190, -97 - +111, and -96 - +46 for the measured volume. DISCUSSION: An estimation formula varies with actual hemothorax volume by hundreds of mL. There is low accuracy in stratifying hemothorax volumes close to 300 mL. Variability between raters was substantially higher with the estimation formula than with manual measurements.

CT Angiography for the Detection of Pulmonary Embolism: Role of Tube Voltage and Contrast Injection Rate on Diagnostic Confidence.

RATIONALE AND OBJECTIVES: Pulmonary CTA is the current standard method to assess for suspected pulmonary embolism. In some instances, the test results in low confidence interpretations. Our purpose was to compare the diagnostic confidence for three different scan protocols. MATERIALS AND METHODS: Pulmonary CTA images from 401 patients were retrospectively analyzed. 202 studies used a tube voltage of 120 kVp and a contrast injection rate of 4 cc/s, 99 studies 120 kVp and 5 cc/s, and 100 studies 100 kVp and 4 cc/s. The level of diagnostic confidence was extracted from the final clinical reports. For each study, attenuation of the pulmonary artery, image noise, signal-to-noise ratio (SNR), and radiation dose were compared. RESULTS: The 120 kVp, 5 cc/s protocol resulted in high diagnostic confidence in 84% of cases, more than with the 120 kVp, 4cc/s (65%) and the 100 kVp protocol (65%, p < 0.004). The 100 kVp protocol had a lower radiation dose, higher image noise, lower SNR, but equal and higher attenuation values of the pulmonary artery. CONCLUSION: The reduction of tube voltage to 100 kVp at 4 cc/s maintains diagnostic confidence with lower radiation exposure, but does not equal the higher confidence achieved with 120 kVp at 5cc/s.

CT Volumetry and Basic Texture Analysis as Surrogate Markers in Advanced Non-small-cell Lung Cancer.

INTRODUCTION: We evaluated volumetric tumor measurements and computed tomography texture analysis as prognostic indicators in patients with advanced non-small-cell lung cancer when compared with the unidimensional tumor size measurements used in Response Evaluation Criteria in Solid Tumors (RECIST). PATIENTS AND METHODS: In a retrospective review, computed tomography examinations in 77 patients with advanced non-small-cell lung cancer were evaluated before and after 2 cycles of chemotherapy. Baseline and changes in tumor diameter, volume, and texture were analyzed. Survival was analyzed with Cox regression analysis and Kaplan-Meier survival statistics. RESULTS: Cox regression analysis demonstrated that only change in tumor volume (exp(B) = 1.006; P = .02) and the initial sum of the largest target lesion diameters predicted survival (exp(B) = 1.013; P = .02). Kaplan-Meier statistics demonstrated that patients with an initial sum of the largest target lesion diameters less than 88 mm had median survival time of 587 days (95% confidence interval [CI], 269-905 days), compared with the survival of those with larger tumor burden of 407 days (95% CI, 235-579 days). Patients in whom tumor volume decreased by more than 29% had a median survival time of 622 days (95% CI, 448-796 days), compared with 305 days for those with less decrease (95% CI, 34-240 days). CONCLUSION: This study demonstrates that change in lung tumor volume is a better marker of patient survival than change of unidimensional diameter measurements in our cohort. If confirmed in larger studies, this suggests that volumetry might improve clinical decision-making for individual patients and allow for faster assessment of new treatments.

WITHDRAWN: Radiology Extenders: Impact on Throughput and Accuracy for Routine Chest Radiographs.

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The Role of Imaging in the Management of Suspected or Known COVID-19 Pneumonia: A Multidisciplinary Perspective.

COVID-19 is an illness caused by a novel coronavirus that has rapidly escalated into a global pandemic leading to an urgent medical effort to better characterize this disease biologically, clinically and by imaging. In this review, we present the current approach to imaging of COVID-19 pneumonia. We focus on the appropriate utilization of thoracic imaging modalities to guide clinical management. We will also describe radiologic findings that are considered typical, atypical and generally not compatible with of COVID-19 infection. Further, we review imaging examples of COVID-19 imaging mimics, such as organizing pneumonia, eosinophilic pneumonia and other viral infections.

The Role of Imaging in the Management of Suspected or Known COVID-19 Pneumonia. A Multidisciplinary Perspective.

Coronavirus disease (COVID-19) is an illness caused by a novel coronavirus that has rapidly escalated into a global pandemic leading to an urgent medical effort to better characterize this disease biologically, clinically, and by imaging. In this review, we present the current approach to imaging of COVID-19 pneumonia. We focus on the appropriate use of thoracic imaging modalities to guide clinical management. We also describe radiologic findings that are considered typical, atypical, and generally not compatible with COVID-19. Furthermore, we review imaging examples of COVID-19 imaging mimics, such as organizing pneumonia, eosinophilic pneumonia, and other viral infections.

Characterization of atherosclerotic plaques in human coronary arteries with 16-slice multidetector row computed tomography by analysis of attenuation profiles.

RATIONALE AND OBJECTIVES: We investigated if 16-slice multidetector row computed tomography (MDCT) allows correct classification of coronary plaques into calcified or noncalcified and further subclassification of noncalcified plaques into either lipid-rich with a necrotic core or fibrous. MATERIALS AND METHODS: Coronary arteries of 30 isolated hearts were filled postmortem with a contrast medium and scanned with a 16-slice MDCT imager (Light Speed 16 pro, GEMS, Milwaukee, WI). Imaging parameters: collimation 16 x 0.625 mm, pitch 0.325, tube voltage 120 kV, tube current 250 mA, and gantry rotation time 500 milliseconds. The images were reformatted perpendicular to the axis of the coronary arteries (AW 4.2 software, GEMS) and analyzed by establishing attenuation profiles of the coronary cross sections (ImageJ 1.33n software, NIH, Bethesda, MD). Results were compared with the correlating histopathologic sections of the arteries. RESULTS: Analysis of 195 CT cross-sections showed a sensitivity and specificity for the correct classification of calcified plaques of 100% and 97.3% and for noncalcified plaques of 80.8% and 95.1%, respectively. The attenuation of epicardial fat ranged from -119 Hounsfield units (HU) to 23 HU (median -71 HU), and from 93 HU to 625 HU (308 HU) for the contrast medium. Calcified plaques showed an attenuation between 333 HU and 1944 HU (1,089 HU), noncalcified plaques between 26 HU and 124 HU (52 HU). Further subclassification of noncalcified plaques showed attenuation values between 26 HU and 67 HU (median 44 HU) for lipid-rich plaques with a necrotic core and from 37 HU to 124 HU (median 67 HU) for fibrous plaques. CONCLUSIONS: Coronary atherosclerotic plaques can be reliably identified and classified as either calcified or noncalcified by 16-slice MDCT in postmortem studies. Further differentiation of noncalcified plaques in either lipid-rich or fibrous is not reliably feasible because of substantial overlap of the attenuation.

Effect of intensive versus standard lipid-lowering treatment with atorvastatin on the progression of calcified coronary atherosclerosis over 12 months: a multicenter, randomized, double-blind trial.

BACKGROUND: Recent clinical trials have suggested that intensive versus standard lipid-lowering therapy provides for additional benefit. Electron-beam computed tomography provides the opportunity to quantify the progression of coronary artery calcification (CAC) in serial measurements. METHODS AND RESULTS: In a multicenter, randomized, double-blind trial, 471 patients (age 61+/-8 years) who had no history of coronary artery disease and no evidence of high-grade coronary stenoses (>50% diameter reduction) were randomized if they had > or =2 cardiovascular risk factors and moderate calcified coronary atherosclerosis as evidenced by a CAC score > or =30. Patients were assigned to receive 80 mg or 10 mg of atorvastatin per day over 12 months. Progression of CAC volume scores could be analyzed in 366 patients. After pretreatment with 10 mg of atorvastatin for 4 weeks, 12 months of study medication reduced LDL cholesterol from 106+/-22 to 87+/-33 mg/dL in the group randomized to receive 80 mg of atorvastatin (P<0.001), whereas levels remained stable in the group randomized to receive 10 mg (108+/-23 at baseline, 109+/-28 mg/dL at the end of the study, P=NS). The mean progression of CAC volume scores, corrected for the baseline CAC volume score, was 27% (95% CI 20.8% to 33.1%) in the 80-mg atorvastatin group and 25% (95% CI 19.1% to 30.8%) in the 10-mg atorvastatin group (P=0.65). CAC progression showed no relationship with on-treatment LDL cholesterol levels. CONCLUSIONS: We did not observe a relationship between on-treatment LDL cholesterol levels and the progression of calcified coronary atherosclerosis. Over a period of 12 months, intensive atorvastatin therapy was unable to attenuate CAC progression compared with standard atorvastatin therapy. The possibility remains that the time window was too short to demonstrate an effect.

Dynamic high-resolution electron-beam CT scanning for the diagnosis of bronchiolitis obliterans syndrome after lung transplantation.

PURPOSES: To determine the diagnostic capabilities of dynamic high-resolution electron-beam (HREB) CT scanning for diagnosing bronchiolitis obliterans syndrome (BOS) in lung transplant recipients. MATERIALS AND METHODS: At the time of follow-up examinations after lung transplantation, 52 patients were examined by dynamic HREB CT scan. Visual signs of small airway disease were assessed and compared with lung function. For numerical analysis, the mean lung attenuation and its SD were determined and compared with the course of lung function tests. RESULTS: On visual analysis, significant parenchymal attenuation inhomogeneities were present in eight of nine patients with manifest BOS, and in two of four patients who developed BOS during follow-up. Thirteen of 20 patients with persistent normal lung function displayed homogeneous lung attenuation. On numerical analysis, mean lung attenuation was significantly lower in patients who developed BOS during follow-up than in patients with persistent normal lung function (both in expiration and inspiration, p < 0.0001). With an optimal threshold, the sensitivity was 100% (4 of 4 patients) and the specificity was 90% (19 of 20 patients). In patients with BOS at the time of the CT scan examination, parenchymal attenuation was less homogeneous than in patients with persistent normal lung function (p < 0.0001). With an optimal threshold, the sensitivity was 78% (7 of 9 patients) and the specificity was 85% (17 of 20 patients). CONCLUSIONS: Dynamic HREB CT of lung transplant recipients correlates well with lung function criteria of BOS at the time of the CT examination and with the subsequent progression to BOS.

Coronary artery calcium scoring: diagnostic accuracy of different software implementations.

PURPOSE: To compare the diagnostic power of different software implementations for the quantification of coronary artery calcium. MATERIALS AND METHODS: Electron beam computed tomography was performed in 109 heart transplant recipients at the same time as catheter coronary angiography and intracoronary ultrasound. Electron beam computed tomography images were analyzed by 3 software packages marketed for the quantification of coronary calcifications using the same software settings, and the resultant calcium scores correlated with the invasive reference methods by Bland-Altman plots and analysis of the receiver operating characteristics. RESULTS: Although all scoring systems displayed close correlations upon regression analysis (r2=0.94-0.99), their ability to detect disease as per the invasive reference method varied significantly in some instances. The area under the ROC curve varied between Az=0.78 and 0.85 for the detection of coronary artery stenosis upon coronary angiography (P=0.05-0.13), and between Az=0.75 and 0.83 for the detection of accelerated intimal proliferation (P=0.03-0.18). CONCLUSIONS: Different software implementations for the quantification of coronary artery calcium load may display diagnostically relevant differences in spite of close direct correlation.

Gauging effective spatial resolution in multirow helical cardiac computed tomography with a dynamic phantom.

PURPOSE: To devise a numerical indicator of image quality for multirow helical cardiac computed tomography (CT) and its relation to temporal resolution. MATERIALS AND METHODS: A pulsatile cardiac assist device was used to simulate cardiac wall motion by mechanically transmitting the device dynamics to a piece of tungsten wire. Wire motion induced by different device rates was captured with an 8-row subsecond helical CT scanner operating with various scanning parameters. Image artifacts were visually assessed and compared with the image point spread function (PSF) using the full width at half maximum (FWHM) area as a numerical estimate of spatial accuracy. RESULTS: At rest, the FWHM area was determined as 1.3 mm2. At a device rate of 60 bpm, the FWHM area ranged from 1.51 mm2 to 21.62 mm2, depending on the time of image reconstruction. Mean reproducibility of the FWHM area measurements was determined as 0.05, whereas visual estimates of motion artifact were highly variable between different readers (kappa = 0.19). Visually determined image quality correlated closely with the FWHM area metric (Spearman's rank correlation, P = 0.0001, rho = 0.841). At a device rate of 100 bpm, the minimum FWHM area was 2.00 mm2 using a single-sector algorithm, 1.41 mm2 using a 2-segment algorithm, and 1.37 mm2 using a 4-segment algorithm. CONCLUSIONS: Use of a pulsatile cardiac assist device could serve as an in vitro test bed for cardiac CT imaging methods. Area FWHM of the PSF correlates well with visually determined image quality of a dynamic phantom, but provides better reproducibility than visual analysis.

Reduction aortoplasty for dilatation of the ascending aorta in patients with bicuspid aortic valve.

BACKGROUND: Individuals with bicuspid aortic valve tend to develop a dilatation of the ascending aorta. It is controversial whether the dilated ascending aorta should be replaced with a tube graft or whether the diameter of the aorta should be reduced by reduction aortoplasty. Furthermore, it is unclear whether an external prosthetic support of the reduction aortoplasty is necessary. The aim of this study is to analyze the results of reduction aortoplasty with and without external prosthetic support. METHODS: Between 1985 and 1999, a total of 115 patients with bicuspid aortic valve and dilatation of the ascending aorta underwent reduction aortoplasty in combination with other types of open-heart procedure at our institution. The diameter of the ascending aorta was measured before and early after surgery and then later between 12 and 144 months (mean 40 months) postoperatively using echocardiography and computed tomography. RESULTS: The reduction aortoplasty decreased the internal diameter of the aorta from 48.7+/-5.1 mm preoperatively to 36.9+/-3.6 mm early after surgery (p = 0.0001). During follow-up, there was no increase of the aortic diameter either in patients with external prosthetic support or in 97 of 106 patients without external prosthetic support. The diameter increased only in 9 (8.5%) of 106 patients without external aortic support by 4 to 8 mm. In patients with postoperative diameter increase, the aortic diameter after operation had been higher than in patients without a postoperative increase of the aortic diameter (41.4+/-3.1 mm vs 36.6+/-3.4 mm; p < 0.0001). CONCLUSIONS: Reduction aortoplasty showed good long-term results in patients with bicuspid aortic valve and dilatation of the ascending aorta. Redilation of the aorta occurred only in patients with a suboptimal diameter reduction.

Implantation of MicroMed DeBakey VAD through left thoracotomy after previous median sternotomy operations.

A left lateral thoracotomy was used for implantation of the continuous-flow MicroMed DeBakey left ventricular assist device in 12 patients with previous heart operations through a median sternotomy. This approach avoids reopening the chest through a median sternotomy and reduces the risk of bleeding and subsequent complications.

[Pre- and post-interventional follow-up of stent graphs with single and multi-slice spiral computerized tomography]. / Ubersicht: Prä- und postinterventionelle Kontrolle von Stentgrafts mittels Ein- und Mehrzeilenspiralcomputertomographie.

PURPOSE: Could contrast enhanced computed tomography replace conventional catheter angiography in the preoperative evaluation of aortic aneurysms before stentgraft implantation? Does multi slice computed tomography have advantages comparing to single slice computed tomography? METHODS: We compared 15 single slice with 13 multi slice computed tomography studies and reconstructions according to there ability to replace conventional catheter angiography in the preoperative evaluation. In the postoperative follow-up 60 single slice computed tomography studies were compared to 60 multi slice studies. RESULTS: By using appropriate reconstructions the spiral computed tomography studies could deliver all information necessary for implantation. In our study no advantage of multi slice computed tomography could be detected. In the postoperative evaluation of stentgrafts our computed tomography scan protocol could detect all relevant complications in single and multi slice computed tomography. No significant advantage of multi slice computed tomography could be detected. CONCLUSION: Contrast enhanced computed tomography is equal to conventional catheter angiography in the pre- and postoperative evaluation of stengrafts. No significant advantage of multi slice versus single slice could be detected.

Assessing response to treatment in non--small-cell lung cancer: role of tumor volume evaluated by computed tomography.

INTRODUCTION: We set out to investigate whether volumetric tumor measurements allow for a prediction of treatment response, as measured by patient survival, in patients with advanced non-small-cell lung cancer (NSCLC). MATERIALS AND METHODS: Patients with nonresectable NSCLC (stage III or IV, n = 100) who were repeatedly evaluated for treatment response by computed tomography (CT) were included in a Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective study. Tumor response was measured by comparing tumor volumes over time. Patient survival was compared with Response Evaluation Criteria in Solid Tumors (RECIST) using Kaplan-Meier survival statistics and Cox regression analysis. RESULTS: The median overall patient survival was 553 days (standard error, 146 days); for patients with stage III NSCLC, it was 822 days, and for patients with stage IV disease, 479 days. The survival differences were not statistically significant (P = .09). According to RECIST, 5 patients demonstrated complete response, 39 partial response, 44 stable disease, and 12 progressive disease. Patient survival was not significantly associated with RECIST class, the change of the sum of tumor diameters (P = .98), nor the change of the sum of volumetric tumor dimensions (P = .17). CONCLUSION: In a group of 100 patients with advanced-stage NSCLC, neither volumetric CT measurements of changes in tumor size nor RECIST class significantly predicted patient survival. This observation suggests that size response may not be a sufficiently precise surrogate marker of success to steer treatment decisions in individual patients.

The role of aortic wall CT attenuation measurements for the diagnosis of acute aortic syndromes.

OBJECTIVES: To determine if measurements of aortic wall attenuation can improve the CT diagnosis of acute aortic syndromes. METHODS: CT reports from a ten year period were searched for acute aortic syndromes (AAS). Studies with both an unenhanced and a contrast enhanced (CTA) series that had resulted in the diagnosis of intramural hematoma (IMH) were reviewed. Diagnoses were confirmed by medical records. The attenuation of aortic wall abnormalities was measured. The observed attenuation threshold was validated using studies from 39 new subjects with a variety of aortic conditions. RESULTS: The term "aortic dissection" was identified in 1206, and IMH in 124 patients' reports. IMH was confirmed in 31 patients, 21 of whom had both unenhanced and contrast enhanced images. All 21 had pathologic CTA findings, and no CTA with IMH was normal. Attenuation of the aortic wall was greater than 45 HUs on the CTA images in all patients with IMH. When this threshold was applied to the new group, sensitivity for diagnosing AAS was 100% (19/19), and specificity 94% (16/17). Addition of unenhanced images did not improve accuracy. CONCLUSIONS: Measurements of aortic wall attenuation in CTA have a high negative predictive value for the diagnosis of acute aortic syndromes.