Nam Ju Lee

Pulmonary Embolism Detected by Pulmonary MDCT Angiography in Older Children and Young Adults: Risk Factor Assessment

OBJECTIVE The purpose of this article is to determine the risk factors for pulmonary embolism (PE) among older children and young adults who underwent pulmonary CT angiography (CTA) for evaluation of clinically suspected PE. MATERIALS AND METHODS We used our hospital information system to retrospectively identify all consecutive patients 19-25 years old who underwent pulmonary CTA for evaluation of clinically suspected PE between July 2004 and March 2011. Two experienced pediatric radiologists retrospectively and independently reviewed a series of 116 consecutive pulmonary CTA studies from this population. Each examination was reviewed for the presence of PE. Seven possible risk factors (immobilization, prior PE or deep venous thrombosis [DVT], cardiac disease, malignancy, hypercoagulable state, excess estrogen, and central venous line placement) were compared between patients with and without PE using univariate statistics, including Student t test and Pearson chi-square test. Multiple logistic regression modeling was used to identify independent risk factors for PE. Receiver operating characteristic curve analysis was applied to determine the optimal cutoff number of risk factors for predicting a pulmonary CTA result positive for PE. RESULTS The study population consisted of 116 patients (34 men and 82 women; mean age, 20.7 ± 1.8 years; range, 18.6-25.4 years) who underwent a total of 116 pulmonary CTA studies. Sixteen (14%) of 116 patients were found to have PE on pulmonary CTA. The level of involvement of PE was segmental in 16 of 31 PEs (52%), lobar in eight (26%), subsegmental in five (16%), and main or central in two (6%). Three risk factors--immobilization (p < 0.001), history of prior PE or DVT (p = 0.001), and cardiac disease (p = 0.004)--were found to be significant independent risk factors for the presence of PE detected by pulmonary CTA. When two or more risk factors were used as the clinical threshold, the sensitivity for positive PE was 75% (12/16 patients) and the specificity was 99% (99/100 patients). CONCLUSION The use of risk factor assessment as a first-line triage tool has the potential to guide more appropriate use of pulmonary CTA in this population, with potential associated reductions in radiation exposure and costs.

Abdominal schwannomas: review of imaging findings and pathology

Schwannomas are typically slow growing, encapsulated benign neoplasms. Visceral schwannomas are rare, and preoperative diagnosis is challenging, as they are often confused with other neoplasms even with advanced imaging studies. Surgical excision is usually needed to establish a definitive diagnosis, as pathology is the “gold standard.” We review the imaging findings of abdominal schwannomas focusing on pancreatic, gastrointestinal, and retroperitoneal/adrenal schwannomas with pathology correlation. We conclude that schwannoma should be included in the broad differential diagnosis of an abdominal mass and that when it is unnecessary radical resection can be avoided.

Cardiac CT angiography for evaluation of acute chest pain

Chest pain is the second most common emergency department (ED) presentation in the United States. Cardiac computed tomography angiography (CCTA) now plays an important role in the evaluation of patients with suspected acute coronary syndrome in the ED setting. In this article, we review the available techniques focused on the use of CCTA to evaluate patients fosr coronary atherosclerosis for timely triage of acute chest pain.

Cardiac MRI vs. myocardial 18F-FDG PET/CT in patients with clinical concern for cardiac sarcoid

Methods 168 patients had both CMR and myocardial PET/CT studies for suspected cardiac sarcoid at a single institution from 11/1/2009 to 9/5/2014. 106 had both studies performed within 3 months; 2 MRIs were nondiagnostic, leaving 104 patients for analysis, mean age 57 (18-80), 33 females and 71 males. The presence of DE on CMR and FDG uptake on PET/CT was compared and stratified by the time between the two exams.

Gastric Heterotopic Pancreas: Computed Tomography With Clinicopathologic Correlation

Abstract Asymptomatic heterotopic pancreas (HP) is benign and can be monitored long term without further intervention. Heterotopic pancreas is sometimes surgically resected because it can be difficult to distinguish HP from neoplastic submucosal masses such as gastrointestinal stromal tumors. Although it is not very common, HP should be considered in the differential diagnosis when diagnosing extramucosal gastric masses to avoid unnecessary intervention. We review gastric HP with pathologic correlation to help with diagnosing HP on computed tomography.

Clinical and Radiographic Predictors of Great Vessel Resection or Reconstruction During Retroperitoneal Lymph Node Dissection for Testicular Cancer

OBJECTIVE To evaluate whether specific clinical or radiographic factors predict inferior vena cava (IVC) or abdominal aortic (AA) resection or reconstruction (RoR) at the time of postchemotherapy retroperitoneal lymph node dissection (RPLND) for germ cell tumors of the testicle. MATERIALS AND METHODS Two hundred seventy-seven patients undergoing postchemotherapy RPLND at two institutions between 2005 and 2015 were identified. Preoperative imaging was reviewed with radiologists blinded to operative details. Univariable and multivariable logistic regressions were performed, and a model was created to predict the need for great vessel RoR using radiographic and clinical factors. RESULTS Of 97 patients with preoperative imaging and clinical data available, 16 (17%) underwent RoR at RPLND. On univariable analysis dominant mass size, degree of circumferential vessel involvement, and vessel deformity were associated with RoR (all P <.05). No patients with clinical stage IIA or IIB disease at diagnosis required RoR. In the multivariable model, mass involvement of the IVC >135° (odds ratio 65.5, 7.8-548, P <.01) and involvement of the AA >330° (odds ratio 29.0, 3.44-245, P <.01) were predictive for RoR. These thresholds yielded a PPV of 48% and 50% and a NPV of 92% and 97% for IVC and AA RoR, respectively. CONCLUSION Degree of circumferential involvement of the great vessels is an independent predictor for resection or reconstruction of the IVC or AA at postchemotherapy RPLND. Patients at high risk of great vessel reconstruction should be informed accordingly and have the proper teams available for complex vascular reconstruction.

Demonstration of Safety and Feasibility of Hydrogel Marking of the Pancreas–Duodenum Interface for Image Guided Radiation Therapy (IGRT) in a Porcine Model: Implications in IGRT for Pancreatic Cancer Patients

Purpose: To test the feasibility and safety of injecting a high-contrast hydrogel marker at the head of the pancreas (HOP) and duodenum interface and assesses the marker visibility on cone beam computed tomography (CBCT) to localize this important boundary during image guided radiation therapy in a porcine model. Methods and Materials: This was a 2-stage study. The feasibility/visibility stage evaluated the ability to place the hydrogel using endoscopic ultrasound guidance on 8 swine (4 euthanized at post-injection day 8, 4 euthanized at post-injection day 22) and assessed the quality of visibility of the marked location on CBCT in the longer-surviving group. The risk assessment stage evaluated the toxicity of targeted intrapancreatic injections (3 swine) and intramural duodenal wall injections (3 swine) to assess toxicity of a misplaced hydrogel injection. All swine underwent postmortem examination and histopathologic studies. Results: The HOP—duodenum interface was successfully marked using hydrogel in 6 of the 8 swine. Histopathologic examination of the 6 successful hydrogel injections showed mild/minimal (4 cases) or moderate (2 cases) reactive inflammation isolated to the injection site. Of the 4 swine survived to 22 days, 3 demonstrated successful hydrogel placement at the HOP—duodenum interface, and this marked location was clearly visible for positional guidance on CBCT. There was no evidence of pancreatitis or duodenal toxicity in the swine undergoing targeted intrapancreatic or intramural duodenum injections for the risk assessment stage. Conclusions We demonstrate the feasibility and safety of injecting a hydrogel marker to highlight the HOP—duodenum interface that has acceptable visibility on CBCT. This technique, translated to humans, enables on-board visualization of this important boundary between the radiation target and dose-limiting, radiosensitive duodenum, facilitating efforts to safely deliver dose-escalated radiation therapy.

Cardiac CT in the Emergency Department: Contrasting Evidence from Registries and Randomized Controlled Trials

Purpose of ReviewTo compare outcomes between registries and randomized controlled trials of coronary computed tomographic angiography (CCTA)-based versus standard of care approaches to the initial evaluation of patients with acute chest pain.Recent FindingsRandomized trials have demonstrated CCTA to be a safe and efficient tool for triage of low- to intermediate-risk patients presenting to the emergency department with chest pain. Recent studies demonstrate heterogeneous result using different standard of care approaches for evaluation of hard endpoints in comparison with standard evaluation. Also, there has been continued concern for increase in subsequent testing after coronary CTA.SummaryAlthough CCTA improves detection of coronary artery disease, it is uncertain if it will bring improvement of long-term health outcomes at this point of time. Careful analysis of the previous results and further investigation will be required to validate evaluation of hard endpoints.

Pancreatic neuroendocrine tumor: review of heterogeneous spectrum of CT appearance

ObjectivePancreatic neuroendocrine tumors (PanNETs) are uncommon pancreatic neoplasms and can be a diagnostic challenge with heterogeneous spectrum of CT appearance. We review CT findings of PanNETs and other mimics.ConclusionPanNETs are typically hypervascular and have avid enhancement on arterial and venous phase images. However, dedicated pancreas protocol may be needed due to their sometimes atypical appearance including transient enhancement. Careful evaluation of CT findings will help differentiate PanNETs from their mimics, and can be used to establish the diagnosis of a PanNETs. Although an accurate diagnosis can be based on serological, urine, and CT scan findings, confirmation is made via pathological examination.

Maximum Aortic Valve Opening Phase for Annulus Sizing in Pre-TAVR CTA

RATIONALE AND OBJECTIVES The optimal phase for the measurement of the aortic annular area for transcatheter aortic valve replacement (TAVR) is not standardized, although most agree that systolic measurements are preferred, when the annulus is larger. We hypothesized that the maximum annular area occurs at the cardiac phase of the maximum aortic valve opening (MAVO) and that this phase can be accurately and reproducibly assessed by visual inspection only. MATERIALS AND METHODS The aortic valve opening area was inspected visually by two readers to determine the MAVO phase. The annular area was measured at the MAVO phase and the typical systolic phase (35% of the R-R interval). Differences in the annular area that would change valve sizing for prostheses were noted. RESULTS Fifty patients (mean age 81) were studied. Ninety percent had the MAVO at the 15%-25% R-R interval. There was high interobserver correlation (0.89) for determining the MAVO phase by visual inspection. For 49 out of 50 patients, the annular area was maximal at the MAVO phase. The mean difference in the annular area between the MAVO phase and 35% was 22.3 (±4.57) mm2. In 12% of the patients, the difference in the annular area changed the recommended size of a self-expanding prosthesis and would have altered the procedure in 32% for balloon-expandable prostheses. CONCLUSIONS Visually assessed MAVO occurs in early systole for most patients and is almost always the cardiac phase of the maximal aortic annular area. This method allows rapid and reproducible determination of the appropriate phase for TAVR planning measurements. Consideration should be given to optimizing pre-TAVR computed tomography acquisitions for early systolic reconstruction and visual determination of the MAVO.