Accuracy of registration techniques and vascular imaging modalities in fusion imaging for aortic endovascular interventions: a phantom study.

BACKGROUND: This study aimed to assess the error of different registration techniques and imaging modalities for fusion imaging of the aorta in a standardized setting using a anthropomorphic body phantom. MATERIALS AND METHODS: A phantom with the 3D printed vasculature of a patient suffering from an infrarenal aortic aneurysm was constructed. Pulsatile flow was generated via an external pump. CTA/MRA of the phantom was performed, and a virtual 3D vascular model was computed. Subsequently, fusion imaging was performed employing 3D-3D and 2D-3D registration techniques. Accuracy of the registration was evaluated from 7 right/left anterior oblique c-arm angulations using the agreement of centerlines and landmarks between the phantom vessels and the virtual 3D virtual vascular model. Differences between imaging modalities were assessed in a head-to-head comparison based on centerline deviation. Statistics included the comparison of means ± standard deviations, student's t-test, Bland-Altman analysis, and intraclass correlation coefficient for intra- and inter-reader analysis. RESULTS: 3D-3D registration was superior to 2D-3D registration, with the highest mean centerline deviation being 1.67 ± 0.24 mm compared to 4.47 ± 0.92 mm. The highest absolute deviation was 3.25 mm for 3D-3D and 6.25 mm for 2D-3D registration. Differences for all angulations between registration techniques reached statistical significance. A decrease in registration accuracy was observed for c-arm angulations beyond 30° right anterior oblique/left anterior oblique. All landmarks (100%) were correctly positioned using 3D-3D registration compared to 81% using 2D-3D registration. Differences in accuracy between CT and MRI were acceptably small. Intra- and inter-reader reliability was excellent. CONCLUSION: In the realm of registration techniques, the 3D-3D method proved more accurate than did the 2D-3D method. Based on our data, the use of 2D-3D registration for interventions with high registration quality requirements (e.g., fenestrated aortic repair procedures) cannot be fully recommended. Regarding imaging modalities, CTA and MRA can be used equivalently.

Rapid study assessment in follow-up whole-body computed tomography in patients with multiple myeloma using a dedicated bone subtraction software.

OBJECTIVES: The diagnostic reading of follow-up low-dose whole-body computed tomography (WBCT) examinations in patients with multiple myeloma (MM) is a demanding process. This study aimed to evaluate the diagnostic accuracy and benefit of a novel software program providing rapid-subtraction maps for bone lesion change detection. METHODS: Sixty patients (66 years ± 10 years) receiving 120 WBCT examinations for follow-up evaluation of MM bone disease were identified from our imaging archive. The median follow-up time was 292 days (range 200-641 days). Subtraction maps were calculated from 2-mm CT images using a nonlinear deformation algorithm. Reading time, correctly assessed lesions, and disease classification were compared to a standard reading software program. De novo clinical reading by a senior radiologist served as the reference standard. Statistics included Wilcoxon rank-sum test, Cohen's kappa coefficient, and calculation of sensitivity, specificity, positive/negative predictive value, and accuracy. RESULTS: Calculation time for subtraction maps was 84 s ± 24 s. Both readers reported exams faster using subtraction maps (reader A, 438 s ± 133 s; reader B, 1049 s ± 438 s) compared to PACS software (reader A, 534 s ± 156 s; reader B, 1486 s ± 587 s; p < 0.01). The course of disease was correctly classified by both methods in all patients. Sensitivity for lesion detection in subtraction maps/conventional reading was 92%/80% for reader A and 88%/76% for reader B. Specificity was 98%/100% for reader A and 95%/96% for reader B. CONCLUSION: A software program for the rapid-subtraction map calculation of follow-up WBCT scans has been successfully tested and seems suited for application in clinical routine. Subtraction maps significantly facilitated reading of WBCTs by reducing reading time and increasing sensitivity. KEY POINTS: • A novel algorithm has been successfully applied to generate motion-corrected bone subtraction maps of whole-body low-dose CT scans in less than 2 min. • Motion-corrected bone subtraction maps significantly facilitate the reading of follow-up whole-body low-dose CT scans in multiple myeloma by reducing reading time and increasing sensitivity.

Endovascular stent-based revascularization of malignant superior vena cava syndrome with concomitant implantation of a port device using a dual venous approach.

PURPOSE: The aim of this paper is to evaluate the safety and efficacy of endovascular revascularization of malignant superior vena cava syndrome (SVCS) and simultaneous implantation of a totally implantable venous access port (TIVAP) using a dual venous approach. MATERIALS AND METHODS: Retrospectively, 31 patients (mean age 67 ± 8 years) with malignant CVO who had undergone revascularization by implantation of a self-expanding stent into the superior vena cava (SVC) (Sinus XL®, OptiMed, Germany; n = 11 [Group1] and Protégé ™ EverFlex, Covidien, Ireland; n = 20 [Group 2]) via a transfemoral access were identified. Simultaneously, percutaneous access via a subclavian vein was used to (a) probe the lesion from above, (b) facilitate a through-and-through maneuver, and (c) implant a TIVAP. Primary endpoints with regard to the SVC syndrome were technical (residual stenosis < 30%) and clinical (relief of symptoms) success; with regard to TIVAP implantation technical success was defined as positioning of the functional catheter within the SVC. Secondary endpoints were complications as well as stent and TIVAP patency. RESULTS: Technical and clinical success rate were 100% for revascularization of the SVS and 100% for implantation of the TIVAP. One access site hematoma (minor complication, day 2) and one port-catheter-associated sepsis (major complication, day 18) were identified. Mean catheter days were 313 ± 370 days. Mean imaging follow-up was 184 ± 172 days. Estimated patency rates at 3, 6, and 12 months were 100% in Group 1 and 84, 84, and 56% in Group 2 (p = 0.338). CONCLUSION: Stent-based revascularization of malignant SVCS with concomitant implantation of a port device using a dual venous approach appears to be safe and effective.

Structural characteristics of the nose in brachycephalic dog breeds analysed by computed tomography. / Strukturelle Besonderheiten der Nase brachyzephaler Hunderassen in der Computertomographie.

INTRODUCTION AND OBJECTIVE: In brachycephalic dogs breeds exaggerated and incorrect breed selection has led to overemphasis of brachycephaly and almost complete loss of the nose. This structural deformity causes severe malfunction of the airway and thus brachycephalic airway syndrome (BAS). It was the aim of this study to examine the anatomical specifics of the brachycephalic nose by computed tomography (CT) and to compare them to those of the normocephalic nose. METHODS: A total of 23 brachycephalic dogs (11 pugs, seven French Bulldogs, five English Bulldogs) and one normocephalic German Shepard dog as reference were examined. Multislice CT images of all animals were analysed. First multisclice images of both nose types were generated. Then, to compare structural differences to normocephalic breeds and among brachycephalic breeds, anatomical parameters were recorded and derived. RESULTS: Extreme shortening of the craniofacial skull and thus of the nasal cavity leads to abnormal configuration of the conchae. Two main types of aberrant conchal growth have been described: 1. rostral, aberrant conchae obstructing the nasal passage (RAC) and 2. caudal aberrant conchae obstructing the choanae (CAC). Furthermore, these conchae are characterised by a low degree of branching and crude lamellae. Measurements of the skull revealed characteristic differences among the brachycephalic dog breeds. The pug had an even shorter craniofacial skull than the French and English Bulldogs. CONCLUSION: The severe intranasal deformities in brachycephalic dogs described here for the first time are the basis for a new pathophysiologic understanding of BAS. CLINICAL RELEVANCE: Detailed structural analysis of aberrant, stenosing conchae (RAC, CAC) is an indispensable prerequisite for the development of an intranasal surgical therapy of BAS in the form of partial laser-assisted turbinectomy (LATE therapy).