Erik Insko

Publications (2)4.77 Total impact

• Article: Use of CT angiography to classify endoleaks after endovascular repair of abdominal aortic aneurysms.

  S William Stavropoulos, Timothy W I Clark, Jeffrey P Carpenter, Ronald M Fairman, Harold Litt, Omaida C Velazquez, Erik Insko, Michael Farner, Richard A Baum
  [show abstract] [hide abstract]
  ABSTRACT: Accurate endoleak detection and classification is critical for the follow-up of patients who have undergone endovascular aneurysm repair (EVAR). This determination is often made with computed tomography angiography (CTA). This investigation was performed to determine the accuracy of CTA in the classification of endoleaks in patients who have undergone EVAR. Thirty-six patients with endoleaks underwent both CTA and conventional contrast digital subtraction angiography (DSA) to determine endoleak etiology. Two independent radiologists determined the source of the endoleak based on a retrospective review of the CTA. The results of the CTA-based endoleak classification were compared to the reference standard, contrast DSA. There was agreement regarding endoleak classification between CTA and DSA on 86% of the patients (31 of 36 patients). Correlation between the CTA reading of the two readers was 94% (34 of 36 patients), yielding a kappa statistic of 0.8. In three patients, the CTA reading incorrectly classified endoleaks as type 2 when the endoleaks were actually type 1 endoleaks on DSA. One patient was incorrectly classified as having a type 1 endoleak on CTA when it was a type 2 endoleak on DSA. Finally, one patient had a type 1 endoleak on DSA that was incorrectly classified as a type 3 endoleak on CTA. The change in CTA endoleak classification based on the DSA resulted in a significant change in patient management in four of the 36 patients (11%). Endoleak classification based on CTA correlates fairly well with DSA findings. However, optimal endoleak management requires performance of selective angiograms with DSA to classify endoleaks that are detected on CTA.
  Journal of Vascular and Interventional Radiology 06/2005; 16(5):663-7. · 2.08 Impact Factor
• Article: Indirect detection of lung perfusion using susceptibility-based hyperpolarized gas imaging.

  Ivan E Dimitrov, Erik Insko, Rahim Rizi, John S Leigh
  [show abstract] [hide abstract]
  ABSTRACT: To address the problem of inadequate signal-to-noise ratio (SNR) encountered in lung perfusion magnetic resonance imaging (MRI) by developing an indirect detection based on the strong hyperpolarized (HP) gas signal. Our model is based on detecting the effects of gadolinium (Gd) flowing through lung capillaries by recording the phase of the nearby alveolar HP gas. In a HP gas 3He phantom we imaged gas phases before and after removing tubes containing paramagnetic solution away from the phantom. We also imaged HP gas phases in pig lungs before and after injection of Gd. Finally, parenchymal spin phase in excised lungs was measured as a function of Gd concentration. In the phantom, the differential phase map displayed a pattern characteristic of a susceptibility-induced dipole field, showing the possibility of an indirect detection. In vivo, the differential phase map showed homogeneous appearance, as expected for uniform perfusion in healthy lungs. Ex vivo, the parenchymal spin phases were shown to depend linearly on Gd concentration. Our method should allow indirect perfusion (Q) and direct ventilation (V) to be assessed simultaneously, thus allowing for diagnosis of V/Q mismatches. The linear dependency of parenchymal spin phase vs. Gd concentration may allow for quantification of lung perfusion.
  Journal of Magnetic Resonance Imaging 03/2005; 21(2):149-55. · 2.70 Impact Factor