Andetta R. Hunsaker

Vascular Enhancement and Image Quality of MDCT Pulmonary Angiography in 400 Cases: Comparison of Standard and Low Kilovoltage Settings

OBJECTIVE The purpose of this study was to investigate the vascular enhancement and image quality of pulmonary CT angiography performed with lower peak kilovoltage settings in a large patient sample. MATERIALS AND METHODS This retrospective study was approved by our institutional review board, which waived the requirement for informed consent. Four hundred patients believed to have a pulmonary embolism were studied. All patients underwent 16- or 64-MDCT with automatic tube current modulation. The 200 patients in the standard peak kilovoltage group (mean age, 57 years; range, 22-95 years) underwent MDCT at 130 or 120 kVp. The 200 patients in the low peak kilovoltage group (mean age, 56 years; range, 21-92 years) underwent MDCT at 110 or 100 kVp. Vascular enhancement was evaluated by measurement of the attenuation value in the main pulmonary artery and segmental and subsegmental arteries. Image noise was quantified by measurement of the SD of the attenuation value in the main pulmonary artery. One blinded radiologist assessed image quality using visual scores. Wilcoxons rank test was used to evaluate differences between the groups. RESULTS Mean vascular enhancement in the main pulmonary artery had significantly higher attenuation values in the low peak kilovoltage group (376.1 +/- 102.9 HU) than in the standard peak kilovoltage group (309.2 +/- 94.8 HU) (p < 0.0001). Mean attenuation values in all measured segmental and subsegmental arteries were significantly higher in the low peak kilovoltage group than in the standard peak kilovoltage group (p < 0.0001). Image noise in the low peak kilovoltage group was significantly higher than in the standard peak kilovoltage group (p < 0.0001). There was no significant difference in the image quality scores of the two groups (p = 0.116). CONCLUSION Lowering kilovoltage improved vascular enhancement without deterioration of image quality. The results of our study confirm previously reported preliminary findings.

The spectrum of Castleman's disease: mimics, radiologic pathologic correlation and role of imaging in patient management.

Castlemans disease (CD) is a rare benign lymphoid disorder with variable clinical course. The two principal histologic subtypes of CD are hyaline-vascular and plasma cell variants and the major clinicoradiological entities are unicentric and multicentric CD. Management of CD is tailored to clinicoradiologic subtype. In this review, we describe the CT, MR and PET/CT findings in Castlemans disease which can help suggest a diagnosis of CD as well as emphasize role of imaging in management of patients with CD.

Axial and Reformatted Four-Chamber Right Ventricle–to–Left Ventricle Diameter Ratios on Pulmonary CT Angiography as Predictors of Death After Acute Pulmonary Embolism

OBJECTIVE The purpose of this article is to retrospectively compare right ventricular-to-left ventricular (RV/LV) diameter ratios measured on the standard axial view versus the reformatted four-chamber view as predictors of mortality after acute pulmonary embolism (PE). MATERIALS AND METHODS Six hundred seventy-four consecutive patients (mean age, 58 years; 372 women) with a diagnosis of acute PE on pulmonary CT angiography were considered. The axial and reformatted four-chamber RV/LV diameter ratios were compared as predictors of 30-day all-cause and PE-related mortality. RESULTS Ninety-seven patients (14%) died within 30 days; 39 deaths were PE related. There was no significant difference in the univariate hazard ratios (HRs) of axial and four-chamber RV/LV diameter ratios greater than 0.9 for both all-cause (HR, 2.13 [95% CI, 1.29-3.51] vs HR, 1.95 [95% CI, 1.22-3.14]; p = 0.74) and PE-related (HR, 19.6 [95% CI, 2.70-143] vs HR, 21.8 [95% CI, 2.99-158]; p = 1.0) mortality. Axial and four-chamber multivariate HRs accounting for potential confounders such as age and cancer were also similar for all-cause (HR, 1.79 [95% CI, 1.07-2.99] vs HR, 1.54 [95% CI, 0.95-2.49]; p = 0.62) and PE-related (HR, 16.3 [95% CI, 2.22-119] vs HR, 17.7 [95% CI, 2.43-130]; p = 1.0) mortality. There was no significant difference in sensitivity, specificity, negative predictive value, or positive predictive value. Axial and four-chamber measurements were well correlated (correlation coefficient, 0.857), and there was no significant difference in overall accuracy for predicting all-cause (area under the curve [AUC], 0.582 vs 0.577; p = 0.72) and PE-related (AUC, 0.743 vs 0.744; p = 1.0) mortality. CONCLUSION The axial RV/LV diameter ratio is no less accurate than the reformatted four-chamber RV/LV diameter ratio for predicting 30-day mortality after PE.

Imaging in Acute Pulmonary Embolism With Special Clinical Scenarios

Major advances in computed tomography (CT) technology, specifically multidetector CT (MDCT) with vastly improved spatial and temporal resolution,1 have led to a surge in the diagnosis of acute pulmonary embolism (PE) using computed tomography pulmonary angiography (CTPA).2,–,5 For persons between 35 and 74 years old, hospital diagnosis rates in 1981 for PE were 127.7 per 100 000 for blacks and 98.2 per 100 000 in whites.6 The reported incidence ranges from 43.7 to 145.0 per 100 000.7 These data are based on epidemiological studies based on physical examination and history, which underestimate the actual frequency of disease.8 However, data from autopsies confirms that only a small number of cases of PE are recognized clinically.8 If untreated, the hospital mortality rate for major PE is 30%, whereas the mortality drops markedly in anticoagulated patients,9 emphasizing the need for rapid, accurate imaging for diagnosis and prognosis. Although CTPA has largely solved the diagnostic question, “Does the patient have PE?” new questions have arisen. These include: Do patients warrant concurrent CTPA plus imaging of the pelvis and lower extremities? What is the risk for subsequent PE after negative CTPA? Is there an ideal management algorithm in patients with isolated subsegmental PE? What is the optimal imaging tool for evaluation of women who are either pregnant or of child bearing age? How can the patient radiation doses be reduced without compromising diagnostic capabilities? This review is to address these questions and looks toward the future of PE imaging. Before the mid 1990s, ventilation perfusion scanning (V/Q) was the imaging modality of choice for the evaluation of patients with clinically suspected acute PE. In 1979, V/Q lung scanning was used for 80% of patients.10 By 2001, CT use surpassed V/Q imaging.4 In …

Routine Pelvic and Lower Extremity CT Venography in Patients Undergoing Pulmonary CT Angiography

OBJECTIVE The purpose of our study was to assess the utility of performing routine pelvic and lower extremity CT venography (CTV) along with pulmonary CT angiography (CTA) in all patients evaluated for pulmonary embolism. MATERIALS AND METHODS Eight hundred twenty-nine consecutive patients (281 men and 548 women) underwent CTA-CTV for pulmonary embolism. Reports were evaluated as follows: positive or negative for pulmonary embolism with or without deep venous thrombosis (DVT) or with nondiagnostic CTV. Coexisting factors of malignancy, previous venous thromboembolism (VTE), recent surgery, and cardiovascular disease comprised the high-risk group of 446 patients. The remaining 383 patients formed the low-risk group. Statistical analysis included four binary predictors (previous VTE, malignancy, cardiovascular disease, and surgery) and three binary outcome variables (pulmonary embolism, DVT, and VTE). Chi-square test and univariate and multivariate regression analyses were performed. RESULTS VTE, pulmonary embolism, and DVT occurred in 152 (18.3%), 124 (15.0%), and 61 (7.3%) of 829 patients, respectively. Between the high-risk and low-risk groups, prevalence of VTE was 114 (25.6%) of 446 and 38 (9.9%) of 383 patients, respectively (p < 0.001); prevalence of pulmonary embolism was 92 (20.6%) of 446 and 32 (8.3%) of 383 patients, respectively (p < 0.001). Isolated DVT was found in 28 (3.4%) of 829 patients. The incremental value of CTV for the entire cohort was 3.4%, 0.72% in the low-risk group (six of 829) and 2.6% (22 of 829) in the high-risk group. For outcome variable VTE, malignancy and previous VTE were statistically significant (p = 0.04 and p < 0.001, respectively); for pulmonary embolism, malignancy and previous VTE were statistically significant (p = 0.03 and p = 0.005, respectively); for DVT, only previous VTE was statistically significant (p < 0.001). CONCLUSION CTV should not be performed routinely in all patients evaluated for pulmonary embolism and may only be useful in patients with a high probability of pulmonary embolism, including those with a history of VTE and possible malignancy.

Cardiac Masses, Part 1: Imaging Strategies and Technical Considerations

OBJECTIVE The objective of this article is to discuss optimal imaging strategies for the evaluation of cardiac masses. The advantages and disadvantages of echocardiography, cardiac MRI, gated cardiac CT, and nuclear imaging will be discussed and specific techniques presented. CONCLUSION Multimodality imaging plays a pivotal role in the diagnosis and surgical planning of cardiac masses. Clinical features, such as patient age, location, and imaging characteristics of the mass will determine the likely differential diagnosis.

Effect of Evidence-based Clinical Decision Support on the Use and Yield of CT Pulmonary Angiographic Imaging in Hospitalized Patients

PURPOSE To determine the effect of clinical decision support (CDS) on the use and yield of inpatient computed tomographic (CT) pulmonary angiography for acute pulmonary embolism (PE). MATERIALS AND METHODS This HIPAA-compliant, institutional review board-approved study with waiver of informed consent included all adults admitted to a 793-bed teaching hospital from April 1, 2007, to June 30, 2012. The CDS intervention, implemented after a baseline observation period, informed providers who placed an order for CT pulmonary angiographic imaging about the pretest probability of the study based on a validated decision rule. Use of CT pulmonary angiographic and admission data from administrative databases was obtained for this study. By using a validated natural language processing algorithm on radiology reports, each CT pulmonary angiographic examination was classified as positive or negative for acute PE. Primary outcome measure was monthly use of CT pulmonary angiography per 1000 admissions. Secondary outcome was CT pulmonary angiography yield (percentage of CT pulmonary angiographic examinations that were positive for acute PE). Linear trend analysis was used to assess for effect and trend differences in use and yield of CT pulmonary angiographic imaging before and after CDS. RESULTS In 272 374 admissions over the study period, 5287 patients underwent 5892 CT pulmonary angiographic examinations. A 12.3% decrease in monthly use of CT pulmonary angiography (26.0 to 22.8 CT pulmonary angiographic examinations per 1000 admissions before and after CDS, respectively; P = .008) observed 1 month after CDS implementation was sustained over the ensuing 32-month period. There was a nonsignificant 16.3% increase in monthly yield of CT pulmonary angiography or percentage of CT pulmonary angiographic examinations positive for acute PE after CDS (P = .65). CONCLUSION Implementation of evidence-based CDS for inpatients was associated with a 12.3% immediate and sustained decrease in use of CT pulmonary angiographic examinations in the evaluation of inpatients for acute PE. for this article.

Contrast Opacification Using a Reduced Volume of Iodinated Contrast Material and Low Peak Kilovoltage in Pulmonary CT Angiography: Objective and Subjective Evaluation

OBJECTIVE The purpose of our study was to evaluate whether a reduced volume of iodinated contrast material for pulmonary CT angiography (CTA) using a low peak kilovoltage (kVp) technique yields equivalent opacification in all vessels. MATERIALS AND METHODS Four hundred fifty-two consecutive pulmonary CTA patients (265 women and 187 men; age range, 18-91 years; mean age, 56.2 years) were retrospectively evaluated. Patients were grouped into those receiving 125 mL (n = 229) and 75 mL (n = 223) of 370 mg I/mL iodinated contrast material. Low kVp was used in all patients. Hounsfield units were measured at lobar, posterobasal segment, posterobasal ramus, and medial basal subsegmental ramus in the left lower lobe. Three thoracic radiologists blinded to contrast dose independently and randomly evaluated the quality of enhancement using a 3-point scale at the same levels. The two-sample Students t test was used to compare contrast opacification between groups; Spearmans correlation and the C-statistic were used to assess objective and subjective measurements. Interreader agreement was measured using Kendalls coefficient. RESULTS Mean contrast opacification differences between 125 mL versus 75 mL were not statistically significant (p > 0.21) at the lobar, segmental, and posterior basal rami, although the mean trended (p = 0.07) toward higher opacification of the medial basal ramus among 75 mL patients. Across all four pulmonary artery segments, there was good concordance between subjective and objective measurements, significantly higher than the null value of 0.50 (p > 0.05). For subsegmental arteries, concordance between objective and subjective measures was greater for the 75 mL group (p < 0.05). There was good interreader concordance, with a concordance coefficient of 0.70 (95% CI, 0.66-0.74). CONCLUSION Both objective and subjective measures of contrast opacification support a reduction from 125 to 75 mL of contrast medium required for pulmonary CTA.

Frequency and Severity of Pulmonary Hemorrhage in Patients Undergoing Percutaneous CT-guided Transthoracic Lung Biopsy: Single-Institution Experience of 1175 Cases

PURPOSE To evaluate the frequency and severity of pulmonary hemorrhage after transthoracic needle lung biopsy (TTLB) and assess possible factors associated with pulmonary hemorrhage. MATERIALS AND METHODS This retrospective study was approved by the institutional review board. The requirement to obtain informed consent was waived. Records from 1113 patients who underwent 1175 TTLBs between January 2008 and April 2013 were retrospectively reviewed. Primary outcomes were pulmonary hemorrhage, documented hemoptysis, and bleeding complications necessitating intervention. Pulmonary hemorrhage was graded as follows: 0, none; 1, less than or equal to 2 cm around the needle; 2, more than 2 cm and sublobar; 3, at least lobar; and 4, hemothorax. Patient, technique, and lesion-related variables were evaluated as predictors of pulmonary hemorrhage. Patient-related variables included main pulmonary artery diameter (mPAD) at computed tomography (CT), pulmonary artery pressures at echocardiography and right-sided heart catheterization, medications, chronic lung disease, bleeding diathesis, and immunodeficiency. Technique- and lesion-related variables included needle gauge, number of passes, pleura-needle angle, lesion size and morphologic characteristics, and distance to pleura. Univariate analysis was performed with χ(2), Fisher exact, and Student t tests. RESULTS Pulmonary hemorrhage occurred in 483 of the 1175 TTLBs (41.1%); hemoptysis was documented in 21 of the 1175 TTLBs (1.8%). Higher-grade hemorrhage (grade 2 or higher) occurred in 201 of the 1175 TTLBs (17.1%); five of the 1175 TTLBs (0.4%) necessitated hemorrhage-related admission. Higher-grade hemorrhage was more likely to occur with female sex (P = .001), older age (P = .003), emphysema (P = .004), coaxial technique (P = .025), nonsubpleural location (P < .001), lesion size of 3 cm or smaller (P < .001), and subsolid lesions (P = .028). Enlarged mPAD at CT (≥2.95 cm) was not significantly associated with higher-grade hemorrhage (P = .430). CONCLUSION Pulmonary hemorrhage after TTLB is common but rarely requires intervention. An enlarged mPAD at CT may not be a risk factor for higher-grade hemorrhage.

Cardiothoracic Applications of 3-dimensional Printing.

Medical 3-dimensional (3D) printing is emerging as a clinically relevant imaging tool in directing preoperative and intraoperative planning in many surgical specialties and will therefore likely lead to interdisciplinary collaboration between engineers, radiologists, and surgeons. Data from standard imaging modalities such as computed tomography, magnetic resonance imaging, echocardiography, and rotational angiography can be used to fabricate life-sized models of human anatomy and pathology, as well as patient-specific implants and surgical guides. Cardiovascular 3D-printed models can improve diagnosis and allow for advanced preoperative planning. The majority of applications reported involve congenital heart diseases and valvular and great vessels pathologies. Printed models are suitable for planning both surgical and minimally invasive procedures. Added value has been reported toward improving outcomes, minimizing perioperative risk, and developing new procedures such as transcatheter mitral valve replacements. Similarly, thoracic surgeons are using 3D printing to assess invasion of vital structures by tumors and to assist in diagnosis and treatment of upper and lower airway diseases. Anatomic models enable surgeons to assimilate information more quickly than image review, choose the optimal surgical approach, and achieve surgery in a shorter time. Patient-specific 3D-printed implants are beginning to appear and may have significant impact on cosmetic and life-saving procedures in the future. In summary, cardiothoracic 3D printing is rapidly evolving and may be a potential game-changer for surgeons. The imager who is equipped with the tools to apply this new imaging science to cardiothoracic care is thus ideally positioned to innovate in this new emerging imaging modality.