Comparison of visibility of in-stent restenosis between conventional- and ultra-high spatial resolution computed tomography: coronary arterial phantom study.

PURPOSE: The purposes of this experimental study were to compare the quantitative and qualitative visibility of in-stent restenosis between conventional-resolution CT (CRCT) and ultra-high-resolution CT (U-HRCT) and to investigate the effects of the image reconstruction techniques on the visualization of in-stent restenosis. MATERIALS AND METHODS: A vessel tube with non-calcified plaque in a 3.0-mm stent was scanned by using CRCT and U-HRCT at 4 stent directions (0, 30, 60, and 90 degrees) to the through-plane direction. Hybrid iterative reconstruction (HIR); model-based iterative reconstruction (MBIR); deep-learning-based reconstruction (DLR) were used as reconstruction methods. The lumen size was assessed using the full width at half maximum method, and image quality was visually evaluated using 4-point scale. RESULTS: U-HRCT had the significantly wider lumen sizes and narrower stent strut thickness than CRCT in three types of the reconstruction methods (P < 0.01). The lumen sizes for U-HRCT with 90 degrees were narrower than those with the other angle directions regardless of the reconstruction methods. Visual score was significantly higher for U-HRCT than CRCT (3.2 ± 0.7 vs 2.0 ± 0.4, P < 0.001). CONCLUSIONS: U-HRCT quantitatively and qualitatively provided better visualization of in-stent restenosis compared to CRCT. Image quality of U-HRCT may be affected by stent angle.

Semiautomatic Volumetry of Low Attenuation of Thoracic Aortic Plaques on Curved Planar Reformations Using MDCT Angiographic Data with 0.5 mm Collimation.

To evaluate the relationship of aortic low attenuation plaque volume (LAPV) on multidetector computed tomography (MDCT) with the abdominal aortic aneurysm (AAA), the coronary arterial disease (CAD, ≥50% stenosis), severe (≥90% stenosis) CAD, hypertension, and long-term (≥10 years) hypertension. Curved planar reformations (CPR) of three segments (the ascending, the arch, and the upper descending aorta) of the thoracic aorta were generated with attenuation-dependent color codes to measure LAPV with 0~29 HU and total noncalcified plaque volume (TNPV) with 0~150 HU in 95 patients. Correlation coefficients were employed to assess the impact of each LAPV and TNPV on AAA, CAD, severe CAD, hypertension, and long-term hypertension. Each Mean LAPV/cm and TNPV/cm was statistically greater in the aortic arch than the ascending (p < 0.001 on each) or the proximal descending segment (p < 0.001 on each). LAPV in the aortic arch has moderate correlations with AAA, severe CAD, and long-term hypertension (r = 0.643, 0.639, 0.662, resp.). Plaque volumes in each aortic segment can be measured clinically and the increasing LAPV in the arch may be a significant factor associated with the development of severe atherosclerosis underlying AAA, severe CAD, and long-term hypertension.

Three-dimensional multimodality fusion imaging as an educational and planning tool for deep-seated meningiomas.

INTRODUCTION: The utility of surgical simulation with three-dimensional multimodality fusion imaging (3D-MFI) has been demonstrated. However, its potential in deep-seated brain lesions remains unknown. The aim of this study was to investigate the impact of 3D-MFI in deep-seated meningioma operations. MATERIAL AND METHODS: Fourteen patients with deeply located meningiomas were included in this study. We constructed 3D-MFIs by fusing high-resolution magnetic resonance (MR) and computed tomography (CT) images with a rotational digital subtraction angiogram (DSA) in all patients. The surgical procedure was simulated by 3D-MFI prior to operation. To assess the impact on neurosurgical education, the objective values of surgical simulation by 3D-MFIs/virtual reality (VR) video were evaluated. To validate the quality of 3D-MFIs, intraoperative findings were compared. The identification rate (IR) and positive predictive value (PPV) for the tumor feeding arteries and involved perforating arteries and veins were also assessed for quality assessment of 3D-MFI. RESULTS: After surgical simulation by 3D-MFIs, near-total resection was achieved in 13 of 14 (92.9%) patients without neurological complications. 3D-MFIs significantly contributed to the understanding of surgical anatomy and optimal surgical view (p < .0001) and learning how to preserve critical vessels (p < .0001) and resect tumors safety and extensively (p < .0001) by neurosurgical residents/fellows. The IR of 3D-MFI for tumor-feeding arteries and perforating arteries and veins was 100% and 92.9%, respectively. The PPV of 3D-MFI for tumor-feeding arteries and perforating arteries and veins was 98.8% and 76.5%, respectively. CONCLUSIONS: 3D-MFI contributed to learn skull base meningioma surgery. Also, 3D-MFI provided high quality to identify critical anatomical structures within or adjacent to deep-seated meningiomas. Thus, 3D-MFI is promising educational and surgical planning tool for meningiomas in deep-seated regions.

Tumor hypoxia and microscopic diffusion capacity in brain tumors: a comparison of (62)Cu-Diacetyl-Bis (N4-Methylthiosemicarbazone) PET/CT and diffusion-weighted MR imaging.

OBJECTIVES: The aim of this study was to clarify the relationship between tumor hypoxia and microscopic diffusion capacity in primary brain tumors using (62)Cu-Diacetyl-Bis (N4-Methylthiosemicarbazone) ((62)Cu-ATSM) PET/CT and diffusion-weighted MR imaging (DWI). METHODS: This study was approved by the institutional human research committee and was HIPAA compliant, and informed consent was obtained from all patients. (62)Cu-ATSM PET/CT and DWI were performed in a total of 40 primary brain tumors of 34 patients with low grade glioma (LGG, n = 13), glioblastoma (GBM, n = 20), and primary central nervous system lymphoma (PCNSL, n = 7). (62)Cu-ATSM PET/CT parameters and apparent diffusion coefficient (ADC) obtained by DWI were compared. RESULTS: High intensity signals by (62)Cu-ATSM PET/CT and DWI in patients with GBM and PCNSL, and low intensity signals in LGG patients were observed. An inverse correlation was found between maximum SUV (SUVmax) and minimum ADC (ADCmin) (r = -0.583, p < 0.0001), and between tumor/brain ratio (T/Bratio) and ADCmin for all tumors (r = -0.532, p < 0.0001). Both SUVmax and T/Bratio in GBM were higher than LGG (p < 0.0001 and p < 0.0001), and those in PCNSL were also higher than GBM (p = 0.033 and p = 0.044). The ADCmin was lower in GBM (p = 0.011) and PCNSL (p = 0.01) than in LGG, while no significant difference was found between GBM and PCNSL (p = 0.90). CONCLUSION: Tumor hypoxia assessed by (62)Cu-ATSM PET/CT correlated with microscopic diffusion capacity obtained by DWI in brain tumors. Both (62)Cu-ATSM PET/CT and DWI were considered feasible imaging methods for grading glioma. However, (62)Cu-ATSM PET/CT provided additional diagnostic information to differentiate between GBM and PCNSL.

Three-dimensional bone-free computed tomographic angiography of aneurysms near the skull base using a new bone-removal application.

PURPOSE: Bone elimination is needed for computed tomography angiography (CTA) because bone structures obscure aneurysms located at the skull base. The purpose of our study was to evaluate the efficacy of three-dimensional (3D)-CTA using an application for bone elimination. MATERIALS AND METHODS: A total of 27 patients with 32 angiographically confirmed aneurysms near the skull base were investigated. The 3D maximum intensity projection (MIP) images were initially obtained using the application. Further postprocessing was performed to obtain the MIP and volume-rendered (VR) images. The quality of the initial MIP images by the application was analyzed. Visualization of aneurysms after further processing was also reviewed. RESULTS: The initial MIP images by the application showed almost bone-free images in 23 of the 27 patients. In 8 patients, the image of the internal carotid artery (ICA) was segmentally removed in the initial MIP images by the application. Further postprocessing was able to recover all loss of the ICA image in these eight patients. For visualizing aneurysms and their necks, VR images with the application were significantly superior to VR images without the application. CONCLUSION: The application for bone elimination allows fast, selective elimination of bony structures and can improve the interpretation of aneurysms near the skull base.

Reduced perfusion reserve in Leukoaraiosis demonstrated using acetazolamide challenge 123I-IMP SPECT.

OBJECTIVE: We examined the relationship between the perfusion reserve as measured by acetazolamide (ACZ)-challenge N-isopropyl-I-123-p-iodoamphetamine (IMP)-single-photon emission computed tomography (SPECT) and the degree of leukoaraiosis (LA) as estimated using magnetic resonance imaging. METHODS: In 51 patients receiving IMP-SPECT with the resting state and ACZ challenge, the unaffected cerebral hemispheres were included in the present study. Mean cerebral blood flow (CBF) in the resting state and ACZ reactivity were acquired. Absolute CBF value and ACZ reactivity were compared among patients with LA grades 0, 1, and 2. The relationship between mean age and LA grade was also assessed. RESULTS: No significant difference in the absolute CBF value in the resting state was observed among the 3 LA groups. Although vasoreactivity in LA grade 0 did not differ from that in grade 1, vasoreactivity in LA grade 2 was significantly lower (P < 0.05) than that in grades 0 or 1. CONCLUSIONS: The perfusion reserve is impaired in advanced LA.

Hepatic infarction following selective hepatic artery embolization with microcoils for iatrogenic biliary hemorrhage.

Purpose: The aim of this study was to explore the relation of collateral filling to ischemic or infarcted liver following selective embolization of hepatic artery with microcoils in patients with iatrogenic hemobilia. Methods: We performed retrospective analysis of clinical outcomes and post-embolization angiograms in eight patients (mean age of 66 years) studied over the last 7 years. Hemobilia occurred after percutaneous biliary drainage (n = 5) and percutaneous hepatic biopsy (n = 3). Causes of bleeding were pseudoaneurysm (n = 6), arterial laceration (n = 1), and direct hepatic artery-to-biliary duct fistula (n = 1). We placed microcoils in the subsegmental (n = 4) or segmental branch (n = 2), or both branches (n = 2), distal and proximal to the bleeding point. Results: We obtained complete hemostasis in all patients (100%). Four patients had no hepatic infarction after embolization. Normal filling of the distal part of the embolized branch through collaterals was seen on post-embolization films. Four patients with no collateral filling experienced liver infarction in the area corresponding to embolized branch. One patient with severe portal stenosis died of hepatic failure. Conclusion: Hepatic infarction is related to lack of immediate collateral flow.

Angiography of hepatic vascular malformations associated with hereditary hemorrhagic telangiectasia.

PURPOSE: To describe the angiographic features of hepatic involvement in hereditary hemorrhagic telangiectasia (HHT), particularly the presence of portovenous shunts. METHODS: We reviewed the angiographic findings of seven patients with HHT. The patients comprised three women and four men with a mean age of 51 years. RESULTS: Intrahepatic telangiectasias were found in all seven patients and shunts between three vascular channels were found in six of seven patients. In the four patients who had portovenous shunts combined with arterioportal shunts, the portovenous shunts were large. Three patients had no portovenous shunts. Two of these patients had arteriovenous shunts, and one had no shunt. The mean age (69 years) of the patients with portovenous shunts was older than those without portovenous shunts (26 years). CONCLUSIONS: Hepatic vascular lesions in HHT are varied, ranging from telangiectasias to large shunts between three vascular channels. In an advanced stage of involvement, large portovenous shunts are present.

Small veins entering the liver.

It is important to recognize and understand focal fatty infiltration and pseudolesions of the liver mimicking liver tumors on CT during arterial portography or helical-CT images. These conditions are caused by venous flow outside the main portal vein. Unless this is borne in mind, incorrect diagnosis and management may follow. This article demonstrates the appearance of the parenchymal changes caused by systemic venous flow and location of the systemic veins entering the liver parenchyma.