John M Barraza

Publications of John M Barraza

• Prognostic value of perfusion defect volume at dual energy CTA in patients with pulmonary embolism: Correlation with CTA obstruction scores, CT parameters of right ventricular dysfunction and adverse clinical outcome.

  Authors: Paul Apfaltrer, Valentin Bachmann, Mathias Meyer, Thomas Henzler, John M Barraza, Joachim Gruettner, Thomas Walter, U Joseph Schoepf, Stefan O Schoenberg, Christian Fink

  European journal of radiology. 04/2012;

  PURPOSE: To investigate the prognostic value of perfusion defect volume (PDvol) at dual-energy-CT-angiography (DE-CTA) in patients with acute pulmonary embolism (PE) by correlating PDvol withPURPOSE: To investigate the prognostic value of perfusion defect volume (PDvol) at dual-energy-CT-angiography (DE-CTA) in patients with acute pulmonary embolism (PE) by correlating PDvol with CTA-obstruction-scores (OS), CT parameters of right-ventricular-dysfunction (RVD), and adverse-clinical-outcome. MATERIALS AND METHODS: DE-CTA of 60 patients (mean age: 65±14.4 years) with PE were analyzed. Iodine maps were generated, and normalized PDvol - defined as volume of perfusion defects/total lung volume - was quantified. Furthermore, established prognostic parameters (Qanadli and Mastora-OS, and CT parameters of RVD) were obtained. CT parameters of RVD - namely the right ventricle/left ventricle (RV/LV) diameter ratio measured on transverse sections (RV/LVtrans), four-chamber views (RV/LV4ch), and RV/LV volume ratios (RV/LVvol) - were assessed. PDvol was correlated with OS, CT parameters of RVD and adverse clinical outcome (defined as the need for intensive care treatment or death). RESULTS: 10 of 60 patients with PE experienced adverse clinical outcome. Patients with adverse clinical outcome showed significantly higher PDvol (35±11% vs. 23±10%, p=0.002), RV/LV ratios (RV/LV4ch 1.46±0.32 vs. 1.18±0.26, p=0.005; RV/LVvol 2.25±1.33 vs. 1.19±0.56, p=0.002) and higher Mastora global scores (52 vs. 13, p=0.02) compared to those without adverse clinical outcome. A weak correlation was observed between PDvol and the Mastora global score (r=0.5; p=0.0003), as well as between PDvol and RV/LV4Ch (r=0.432, p=0.0006). No correlation was found between PDvol and the Qanadli score or the remainder of the RVD-CT parameters. CONCLUSION: The extent of perfusion defects as assessed by DE-CTA correlates with adverse clinical outcome in patients with PE. Therefore, volumetric quantification of perfusion defects at DE-CTA allows the identification of low-risk patients who do not require intensified monitoring and treatment.

• Contrast-enhanced dual-energy CT of gastrointestinal stromal tumors: is iodine-related attenuation a potential indicator of tumor response?

  Authors: Paul Apfaltrer, Mathias Meyer, Caroline Meier, Thomas Henzler, John M Barraza, Dietmar J Dinter, Peter Hohenberger, U Joseph Schoepf, Stefan O Schoenberg, Christian Fink

  Investigative radiology. 09/2011; 47(1):65-70.

  To assess the correlation of true nonenhanced (TNE) and virtually nonenhanced (VNE) images of abdominal dual-energy computed tomography (DECT) in patients with metastatic gastrointestinal stromalTo assess the correlation of true nonenhanced (TNE) and virtually nonenhanced (VNE) images of abdominal dual-energy computed tomography (DECT) in patients with metastatic gastrointestinal stromal tumors (GIST), and further to investigate the correlation of iodine-related attenuation (IRA) of DECT with the Choi criteria. Twenty-four consecutive patients (5 women aged 61 ± 10 years) with metastatic GIST underwent DECT of the abdomen (80 kV, 140 kV) using first-generation dual-source computed tomography (CT). All patients had at least one or more liver lesions (median, 4; maximum, 9). Image data were processed with a dedicated DECT software algorithm designed for evaluation of iodine distribution in soft tissue lesions, and VNE CT images were generated. The tumor density (according to Choi criteria) and the maximum transverse diameter of the lesions (according to Response Evaluation Criteria in Solid Tumors [RECIST]) were determined. TNE and VNE lesion attenuation and Choi criteria and IRA were correlated with each other. A total of 291 liver lesions were evaluated, of which 220 were cystic and 71 were solid. The mean lesion size was 4.5 ± 3.2 cm (1.1-18.7 cm). The mean attenuation of all lesions was significantly higher in the TNE images than in the VNE images (P=0.0001). Pearson statistics revealed an excellent correlation of r=0.843 (P=0.0001) between IRA and Choi criteria for all lesions. DECT showed significantly higher IRA in progressive (23.3 ± 9.5 HU) lesions compared with stable or regressive (17.8 ± 9.1 HU) lesions (P=0.0185). Similarly, the Choi criteria differed significantly between progressive (39.9 ± 12.8 HU) and stable/regressive (31.1 ± 10.3 HU) lesions (P=0.0003). DECT is a promising imaging method for the assessment of treatment response in GIST, as IRA might be a more robust response parameter than the Choi criteria. VNE CT data calculated from DECT may eliminate the need for acquisition of a separate unenhanced data set.