Philip Costello

Right Ventricular Enlargement on Chest Computed Tomography A Predictor of Early Death in Acute Pulmonary Embolism

Background—In patients with acute pulmonary embolism (PE), rapid and accurate risk assessment is paramount in selecting the appropriate treatment strategy. Right ventricular (RV) enlargement on chest CT has previously been shown to correlate with an unstable hospital course, but its role as a predictor of death is unknown. Methods and Results—We evaluated 431 consecutive patients (mean age, 59±16 years; 55% women) with acute PE confirmed by multidetector-row chest CT. With the use of multiplanar reformats of axial CT data, CT 4-chamber (4-CH) views were reconstructed and right and left ventricular dimensions (RVD, LVD) were measured. RV enlargement, defined as RVD/LVD >0.9, was present in 276 (64.0%; 95% CI, 59.5% to 68.6%) patients. Thirty-day mortality rate was 15.6% (95% CI, 11.3% to 19.9%) in patients with and 7.7% (95% CI, 3.5% to 12.0%) without RV enlargement (log rank, P=0.018). The hazard ratio of RVD/LVD >0.9 for predicting 30-day death was 3.36 (95% CI, 1.13 to 9.97; P=0.029). On multivariable analysis, RV enlargement predicted 30-day death (hazard ratio, 5.17; 95% CI, 1.63 to 16.35; P=0.005) after adjusting for pneumonia (hazard ratio, 2.95; 95% CI, 1.19 to 3.83; P=0.002), cancer (hazard ratio, 2.13; 95% CI, 1.19 to 3.83; P=0.011), chronic lung disease (hazard ratio, 2.00; 95% CI, 1.04 to 3.86; P=0.039), and age (hazard ratio, 1.03; 95% CI, 1.01 to 1.05; P=0.005). Conclusions—In patients with acute PE, RV enlargement on reconstructed CT 4-CH view helps predict early death.

Right Ventricular Enlargement on Chest Computed Tomography Prognostic Role in Acute Pulmonary Embolism

Background—We investigated the prognostic role of right ventricular enlargement on multidetector-row chest CT in acute pulmonary embolism (PE). Methods and Results—We studied 63 patients with CT-confirmed PE who underwent echocardiography within the ensuing 24 hours. Adverse clinical events, defined as 30-day mortality or the need for cardiopulmonary resuscitation, mechanical ventilation, pressors, rescue thrombolysis, or surgical embolectomy, were present in 24 patients. We performed off-line CT measurements of right and left ventricular dimensions (RVD, LVD) with axial and 2-dimensional reconstructed 4-chamber (4-CH) views. The proportion of patients with RVD/LVD>0.9 on the axial view was similar in patients with (70.8%) and those without adverse events (71.8%; P =0.577). In contrast, RVD/LVD>0.9 on the 4-CH view was more common in patients with (80.3%) than without (51.3%; P =0.015) adverse events. The area under the curve of RVD/LVD from the axial and 4-CH views for predicting adverse events was 0.667 and 0.753, respectively. Sensitivity and specificity of RVD/LVD>0.9 for predicting adverse events were 37.5% and 92.3% on the axial view and 83.3% and 48.7% on the reconstructed 4-CH view, respectively. RVD/LVD>0.9 on the 4-CH view was an independent predictor for adverse events (OR, 4.02; 95% CI, 1.06 to 15.19; P =0.041) when adjusted for age, obesity, cancer, and recent surgery. Conclusions—Right ventricular enlargement on the reconstructed CT 4-CH views predicts adverse clinical events in patients with acute PE. Ventricular CT measurements obtained from 4-CH views are superior to those from axial views for identifying high-risk patients.

Analysis of prostate and seminal vesicle motion: Implications for treatment planning

PURPOSE To quantify prostate and seminal vesicle positional changes (target motion) between treatment planning and delivery, and to identify the factors contributing to target motion. METHODS AND MATERIALS Thirty patients with adenocarcinoma of the prostate were prospectively evaluated by analyzing two sequential planning computerized tomography (CT) scans (S1, obtained prior to treatment, and S2, obtained during the fourth week of treatment) for each patient. All anatomical volumes of interest (soft tissue and bony) were reconstructed from transverse CT images and projected onto anterior and lateral beams-eye view projections. Positional changes between S1 and S2 were eliminated by applying a rigid body translation and rotation. Target motion was then measured by recording the positional change between S1 and S2 at the edges (right, left, superior, inferior). Potential correlation of target motion with bladder volume, rectal volume, and rectal diameter changes were evaluated by linear regression analysis. RESULTS Neither the prostate nor seminal vesicles remained fixed with respect to bony anatomy between S1 and S2. The distribution of positional changes were generally small (< 0.5 cm), but maximum displacements of 1.5-2.2 cm did occur, particularly in the lateral view. In this study, bladder volume changes between the scans were small and did not correlate with target motion (P = 0.67). Both rectal volume and rectal diameter changes correlated with target motion for both the prostate (p = 0.004 and 0.005, respectively) and seminal vesicles (p < 0.001 and < 0.001, respectively). However, neither the initial rectal volume nor the initial rectal diameter could be used to predict subsequent target motion when evaluated either singly or as part of a multiple regression model. CONCLUSIONS Target motion occurs during the course of treatment planning and delivery and should be considered when designing conformal radiation fields. Although the target position at the time of planning CT may differ substantially from the mean treatment position, target motion cannot be predicted by evaluating simply measured parameters from a single scan, or double scan sequence.

Spiral Computed Tomography for Acute Pulmonary Embolism

There is still considerable debate about the optimal diagnostic imaging modality for acute pulmonary embolism. If imaging is deemed necessary from an initial clinical evaluation such as d-dimer testing, options include nuclear medicine scanning, catheter pulmonary angiography, and spiral CT. In many institutions, spiral CT is becoming established as the first-line imaging test in daily clinical practice. With spiral CT, thrombus is directly visualized, and both mediastinal and parenchymal structures are evaluated, which may provide important alternative or additional diagnoses. However, limitations for the accurate diagnosis of small peripheral emboli, with a reported miss rate of up to 30% with single-slice spiral CT so far, have prevented the unanimous embrace of spiral CT as the new standard of reference for imaging pulmonary embolism. The clinical significance of the detection and treatment of isolated peripheral pulmonary emboli is uncertain. Evidence is accumulating that it is safe practice to withhold anticoagulation in patients with suspected pulmonary embolism on the basis of a negative spiral CT study. Remaining concerns about the accuracy of spiral CT for pulmonary embolism detection may be overcome by the introduction of multidetector-row spiral CT. This widely available technology has improved visualization of peripheral pulmonary arteries and detection of small emboli. The most recent generation of multidetector-row spiral CT scanners appears to outperform competing imaging modalities for the accurate detection of central and peripheral pulmonary embolism. In this review, we assess the current role and future potential of CT in the diagnostic algorithm of acute pulmonary embolism.

CT Signs of Right Ventricular Dysfunction: Prognostic Role in Acute Pulmonary Embolism

OBJECTIVES The purpose of this study was to compare the prognostic role of various computed tomography (CT) signs of right ventricular (RV) dysfunction, including 3-dimensional ventricular volume measurements, to predict adverse outcomes in patients with acute pulmonary embolism (PE). BACKGROUND Three-dimensional ventricular volume measurements based on chest CT have become feasible for routine clinical application; however, their prognostic role in patients with acute PE has not been assessed. METHODS We evaluated 260 patients with acute PE for the following CT signs of RV dysfunction obtained on routine chest CT: abnormal position of the interventricular septum, inferior vena cava contrast reflux, right ventricle diameter (RVD) to left ventricle diameter (LVD) ratio on axial sections and 4-chamber (4-CH) views, and 3-dimensional right ventricle volume (RVV) to left ventricle volume (LVV) ratio. Comorbidities and fatal and nonfatal adverse outcomes according to the MAPPET-3 (Management Strategies and Prognosis in Pulmonary Embolism Trial-3) criteria within 30 days were recorded. RESULTS Fifty-seven patients (21.9%) had adverse outcomes, including 20 patients (7.7%) who died within 30 days. An RVD(axial)/LVD(axial) ratio >1.0 was not predictive for adverse outcomes. On multivariate analysis (adjusting for comorbidities), abnormal position of the interventricular septum (hazard ratio [HR]: 2.07; p = 0.007), inferior vena cava contrast reflux (HR: 2.57; p = 0.001), RVD(4-CH)/LVD(4-CH) ratio >1.0 (HR: 2.51; p = 0.009), and RVV/LVV ratio >1.2 (HR: 4.04; p < 0.001) were predictive of adverse outcomes, whereas RVD(4-CH)/LVD(4-CH) ratio >1.0 (HR: 3.68; p = 0.039) and RVV/LVV ratio >1.2 (HR: 6.49; p = 0.005) were predictive of 30-day death. CONCLUSIONS Three-dimensional ventricular volume measurement on chest CT is a predictor of early death in patients with acute PE, independent of clinical risk factors and comorbidities. Abnormal position of the interventricular septum, inferior vena cava contrast reflux, and RVD(4-CH)/LVD(4-CH) ratio are predictive of adverse outcomes, whereas RVD(axial)/LVD(axial) ratio >1.0 is not.

Dual-energy CT of the heart for diagnosing coronary artery stenosis and myocardial ischemia-initial experience

We aimed to evaluate the feasibility of diagnosing coronary stenosis and myocardial ischemia with a single dual-energy CT (DECT) acquisition. Thirty-five patients underwent contrast-enhanced, ECG-gated DECT of the heart while independently operating the two tubes of a dual-source CT system at high- and low-energy X-ray spectra. From the same raw data, coronary CTA (cCTA) studies were reconstructed for stenosis detection, and the myocardial blood-pool was analyzed by determining the tissue iodine content. Two independent observers analyzed all studies for stenosis and myocardial blood-pool deficits. Results were correlated with SPECT, coronary catheterization and cCTA on a segmental basis. cCTA had 98% sensitivity, 88% specificity and 92% accuracy for detection of >50% stenosis. DECT detected myocardial ischemia with 84% sensitivity, 94% specificity and 92% accuracy. Our initial experience may warrant further exploration of DECT as a possibly feasible single imaging investigation for the comprehensive diagnosis of coronary stenosis and myocardial ischemia.

Comparison of Dual-Energy Computed Tomography of the Heart With Single Photon Emission Computed Tomography for Assessment of Coronary Artery Stenosis and of the Myocardial Blood Supply

To evaluate the performance of dual-energy computed tomography (CT) for integrative imaging of the coronary artery morphology and the myocardial blood supply, 36 patients (15 women, mean age 57 +/- 11 years) with equivocal or incongruous single photon emission CT (SPECT) results were investigated by a single-contrast medium-enhanced, retrospectively electrocardiographic-gated dual-energy CT (DECT) scan with simultaneous acquisition of high and low x-ray spectra. Thirteen patients subsequently underwent invasive coronary angiography (ICA). The DECT data were used to reconstruct anatomic coronary CT angiographic images and to map the myocardial iodine distribution within the left ventricular myocardium. Two independent observers analyzed all DECT studies for stenosis and myocardial iodine defects. A segmental comparison was performed between the stress/rest SPECT perfusion defects and DECT iodine defects and between the ICA and coronary CT angiographic findings for stenosis. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were estimated, along with the kappa statistics. Overall, DECT had 92% sensitivity and 93% specificity, with 93% accuracy for detecting any type of myocardial perfusion defect seen on SPECT. Contrast defects at DECT correctly identified 85 (96%) of 89 fixed and 60 (88%) of 68 reversible myocardial perfusion defects. The interobserver agreement was very good (weighted kappa = 0.87). Compared with ICA, coronary CT angiography had 90% sensitivity, 94% specificity, and 93% accuracy for the detection of >50% stenosis. In conclusion, our initial experience suggests that DECT, as a single examination, might be promising for the integrative analysis of the coronary artery morphology and the myocardial blood supply and is in good agreement with ICA and SPECT.

Iso-Osmolality versus Low-Osmolality Iodinated Contrast Medium at Intravenous Contrast-enhanced CT: Effect on Kidney Function

PURPOSE To determine the effects of iso-osmolality contrast medium compared with a low-osmolality agent on renal function (serum creatinine [SCr] and glomerular filtration rate [GFR]) in high-risk patients undergoing intravenous contrast material-enhanced CT. MATERIALS AND METHODS This HIPAA-compliant study was IRB-approved; formal consent was obtained. One hundred seventeen patients (83 men, 34 women; mean age, 64.3 years; range, 18-86 years) with decreased renal function underwent contrast-enhanced CT with either iso-osmolality iodixanol (n = 61) or low-osmolality iopromide (n = 56). Outcome measures were of SCr increase or GFR decrease for 3 days after CT, a SCr increase (of >or=0.5 mg/dL [44.2 micromol/L, 25%] or >or=1.0 mg/dL [88.4 micromol/L, 50%]), a GFR reduction (of >or=5 mL/min), and patient outcome at 30- and 90-day follow-up. RESULTS Iodixanol decreased SCr (mean +/- standard deviation) from 1.77 mg/dL +/- 0.24 (156.47 micromol/L +/- 21.22) at baseline to 1.65 mg/dL +/- 0.35 (145.86 micromol/L +/- 30.94, P = .046) at day 1, 1.73 mg/dL +/- 0.53 (152.93 micromol/L +/- 46.85, not significant) at day 2, and 1.73 mg/dL +/- 0.55 (152.93 micromol/L +/- 48.62, not significant) at day 3 (not significant). Iopromide increased SCr from 1.75 mg/dL +/- 0.32 (154.7 micromol/L +/- 28.29) at baseline to 1.8 mg/dL +/- 0.42 (159.12 micromol/L +/- 15.59) at day 1, 1.77 mg/dL +/- 0.49 (156.47 micromol/L +/- 43.32) at day 2, and 1.77 mg/dL +/- 0.62 (156.47 micromol/L +/- 54.81) at day 3 (not significant). Iodixanol increased and iopromide decreased GFR on all 3 days after CT (not significant). Fewer patients in the iodixanol group (8.5%) than in the iopromide group (27.8%) had SCr increase 0.5 mg/dL or higher (>or=25%, P = .012). Two patients in each group had SCr increase of 1.0 mg/dL or more (not significant). More patients in the iopromide group (42.3%) than in the iodoxanol group (24.1%) had a GFR reduction of 5 mL/min or higher (P = .0426). No patient had a contrast material-related adverse event at 30- or 90-day follow-up. CONCLUSION Intravenous contrast material application in high-risk patients is unlikely to be associated with permanent adverse outcomes. SCr levels after contrast material administration are lower in iodixanol than iopromide groups.

Right Heart: Split-Bolus Injection of Diluted Contrast Medium for Visualization at Coronary CT Angiography

PURPOSE To retrospectively compare a split-bolus contrast medium injection protocol with a biphasic and a monophasic protocol in terms of visualization of the right and left heart, contrast medium-related streak artifacts, and level of attenuation in the cardiac chambers and coronary arteries at coronary computed tomographic (CT) angiography. MATERIALS AND METHODS The human research committee approved this HIPAA-compliant study and waived informed consent. Seventy-five patients had undergone 64-section coronary CT angiography: 25 were injected by using a monophasic, contrast-medium-only protocol with a single-syringe injector; 25 were injected by using a biphasic protocol with a dual-syringe injector; and 25 were injected by using a split-bolus protocol with a dual-syringe injector and an initial bolus of contrast medium followed by 50 mL of a 70%:30% saline-to-contrast medium mixture and a 30-mL saline chaser. Two radiologists rated the visualization of right and left heart structures and the degree of streak artifacts. One observer performed attenuation measurements of the cardiac chambers and of the coronary arteries. Data were analyzed with one-way analysis of variance and Duncan post-hoc multiple comparison procedures. RESULTS Data for 27 women and 48 men (mean age, 62 years) were included. Mean contrast medium attenuation in the right heart was significantly (P < .001) higher in the split-bolus group than in the biphasic injection group but was significantly (P < .001) lower than in the monophasic injection group. For the left heart and the coronary arteries, there were no significant differences among the three groups. Artifacts occurred less frequently (P < .001) in the biphasic and split-bolus groups than in the monophasic group. Visualization of right heart structures was rated significantly (P < .05) better in the split-bolus group than in the two other groups, while there was no difference for visualization of left heart structures. CONCLUSION Split-bolus injection provides sufficient attenuation for visualization of the right heart, while streak artifacts from high-attenuation contrast material can generally be avoided and arterial attenuation is maintained.

Pediatric cardiovascular CT angiography: radiation dose reduction using automatic anatomic tube current modulation.

OBJECTIVE The purpose of this study was to assess the effect of weight-based scanning protocols and automatic tube current modulation on the tube current-time product and image quality at pediatric cardiovascular 64-MDCT angiography. MATERIALS AND METHODS Our pediatric cardiovascular 64-MDCT protocols use a weight-based algorithm to determine nominal tube voltage settings with 80, 100, and 120 kV. Automatic tube current modulation was used for each case. The mAs, volume CT dose index (CTDI(vol)), and dose-length product (DLP) values were recorded and the effective dose calculated. On the basis of the selected nominal tube current, the dose values that would have been delivered without tube current modulation were also calculated. Scans were compared with 16-MDCT using 120 kVp and 120 mAs. Two radiologists independently rated image quality on a 5-point scale. Image noise was objectively measured within four different regions of interest. Findings at CT were clinically correlated with results of cardiac sonography, angiography, or surgery. RESULTS Thirty-eight 64-MDCT and 30 16-MDCT scans were evaluated. Mean diagnostic quality for 64-MDCT was rated at 3.6 +/- 0.4 and mean image noise was 8.9 +/- 4.5 H. Results with 16-MDCT were not significantly different: diagnostic quality (3.6 +/- 0.4; p = 0.97) and image noise (9.1 +/- 2.8 H; p = 0.31). Scanning with automatic tube current modulation significantly (p < 0.05) reduced the tube current time-product compared with scanning without automatic tube current modulation (-57.8%/54.1/128 mAs) or with 16-MDCT (-47.9%/54.1/104.37 mAs), respectively. The mAs values were significantly (p < 0.05) lower for 80 kVp than for 100 or 120 kVp scans, but image quality and image noise were not significantly (p = 0.24) different. Agreement between MDCT and clinical findings was excellent. CONCLUSION Under simulated conditions, automatic tube current modulation combined with low tube voltage settings significantly reduced radiation exposure and thus appears preferable in pediatric cardiovascular 64-MDCT.