Sebastian Winklhofer

Computed tomographic perfusion imaging for the prediction of response and survival to transarterial radioembolization of liver metastases.

PurposeThe purpose of this study was to evaluate prospectively, in patients with liver metastases, the ability of computed tomographic (CT) perfusion to predict the morphologic response and survival after transarterial radioembolization (TARE). MethodsThirty-eight patients (22 men; mean [SD] age, 63 [12] years) with otherwise therapy-refractory liver metastases underwent dynamic, contrast-enhanced CT perfusion within 1 hour before treatment planning catheter angiography, for calculation of the arterial perfusion (AP) of liver metastases, 20 days before TARE with Yttrium-90 microspheres. Treatment response was evaluated morphologically on follow-up imaging (mean, 114 days) on the basis of the Response Evaluation Criteria in Solid Tumors criteria (version 1.1). Pretreatment CT perfusion was compared between responders and nonresponders. One-year survival was calculated including all 38 patients using the Kaplan-Meier curves; the Cox proportional hazard model was used for calculating predictors of survival. ResultsFollow-up imaging was not available in 11 patients because of rapidly deteriorating health or death. From the remaining 27, a total of 9 patients (33%) were classified as responders and 18 patients (67%) were classified as nonresponders. A significant difference in AP was found on pretreatment CT perfusion between the responders and the nonresponders to the TARE (P < 0.001). Change in tumor size on the follow-up imaging correlated significantly and negatively with AP before the TARE (r = −0.60; P = 0.001). Receiver operating characteristics analysis of AP in relation to treatment response revealed an area under the curve of 0.969 (95% confidence interval, 0.911–1.000; P < 0.001). A cutoff AP of 16 mL per 100 mL/min was associated with a sensitivity of 100% (9/9) (95% CI, 70%–100%) and a specificity of 89% (16/18) (95% CI, 62%–96%) for predicting therapy response. A significantly higher 1-year survival after the TARE was found in the patients with a pretreatment AP of 16 mL per 100 mL/min or greater (P = 0.028), being a significant, independent predictor of survival (hazard ratio, 0.101; P = 0.015). ConclusionsArterial perfusion of liver metastases, as determined by pretreatment CT perfusion imaging, enables prediction of short-term morphologic response and 1-year survival to TARE.

Transcatheter based electromechanical mapping guided intramyocardial transplantation and in vivo tracking of human stem cell based three dimensional microtissues in the porcine heart

Stem cells have been repeatedly suggested for cardiac regeneration after myocardial infarction (MI). However, the low retention rate of single cell suspensions limits the efficacy of current therapy concepts so far. Taking advantage of three dimensional (3D) cellular self-assembly prior to transplantation may be beneficial to overcome these limitations. In this pilot study we investigate the principal feasibility of intramyocardial delivery of in-vitro generated stem cell-based 3D microtissues (3D-MTs) in a porcine model. 3D-MTs were generated from iron-oxide (MPIO) labeled human adipose-tissue derived mesenchymal stem cells (ATMSCs) using a modified hanging-drop method. Nine pigs (33 ± 2 kg) comprising seven healthy ones and two with chronic MI in the left ventricle (LV) anterior wall were included. The pigs underwent intramyocardial transplantation of 16 × 10(3) 3D-MTs (1250 cells/MT; accounting for 2 × 10(7) single ATMSCs) into the anterior wall of the healthy pigs (n = 7)/the MI border zone of the infarcted (n = 2) of the LV using a 3D NOGA electromechanical mapping guided, transcatheter based approach. Clinical follow-up (FU) was performed for up to five weeks and in-vivo cell-tracking was performed using serial magnet resonance imaging (MRI). Thereafter, the hearts were harvested and assessed by PCR and immunohistochemistry. Intramyocardial transplantation of human ATMSC based 3D-MTs was successful in eight animals (88.8%) while one pig (without MI) died during the electromechanical mapping due to sudden cardiac-arrest. During FU, no arrhythmogenic, embolic or neurological events occurred in the treated pigs. Serial MRI confirmed the intramyocardial presence of the 3D-MTs by detection of the intracellular iron-oxide MPIOs during FU. Intramyocardial retention of 3D-MTs was confirmed by PCR analysis and was further verified on histology and immunohistochemical analysis. The 3D-MTs appeared to be viable, integrated and showed an intact micro architecture. We demonstrate the principal feasibility and safety of intramyocardial transplantation of in-vitro generated stem cell-based 3D-MTs. Multimodal cell-tracking strategies comprising advanced imaging and in-vitro tools allow for in-vivo monitoring and post-mortem analysis of transplanted 3D-MTs. The concept of 3D cellular self-assembly represents a promising application format as a next generation technology for cell-based myocardial regeneration.

Consensus conference on core radiological parameters to describe lumbar stenosis - an initiative for structured reporting

AbstractPurposeTo define radiological criteria and parameters as a minimum standard in a structured radiological report for patients with lumbar spinal stenosis (LSS) and to identify criteria and parameters for research purposes.Material and methodsAll available radiological criteria and parameters for LSS were identified using systematic literature reviews and a Delphi survey. We invited to the consensus meeting, and provided data, to 15 internationally renowned experts from different countries. During the meeting, these experts reached consensus in a structured and systematic discussion about a core list of radiological criteria and parameters for standard reporting.ResultsWe identified a total of 27 radiological criteria and parameters for LSS. During the meeting, the experts identified five of these as core items for a structured report. For central stenosis, these were “compromise of the central zone” and “relation between fluid and cauda equina”. For lateral stenosis, the group agreed that “nerve root compression in the lateral recess” was a core item. For foraminal stenosis, we included “nerve root impingement” and “compromise of the foraminal zone”.ConclusionAs a minimum standard, five radiological criteria should be used in a structured radiological report in LSS. Other parameters are well suited for research.Key Points• The five most important radiological criteria for standard clinical reporting were selected • The five most important quantitative radiological parameters for research purposes were selected • These core criteria could help standardize the communication between health care providers

A Systematic Review of Semiquantitative and Qualitative Radiologic Criteria for the Diagnosis of Lumbar Spinal Stenosis

OBJECTIVE The objective of our study was to perform a systematic review of the semiquantitative and qualitative radiologic criteria that are used for the diagnosis of lumbar spinal stenosis (LSS). MATERIALS AND METHODS A four-step systematic literature search including the MEDLINE database was performed by an experienced librarian to reveal all semiquantitative or qualitative radiologic criteria used for the diagnosis of LSS. The precise definitions of all criteria, normal or abnormal values (if applicable), and intra- and interrater reliability were noted by two independent readers. Descriptive statistics were used. RESULTS A total of 14 semiquantitative or qualitative radiologic parameters were identified and distinguished according to relevant anatomic spaces into criteria for central canal stenosis, lateral (recess) stenosis, and foraminal stenosis. Great variability in terms of the exact definitions of the criteria was found. For 10 of the 14 criteria, the intra- and interrater reliability data were found with kappa values ranging from 0.01 to 1.0. CONCLUSION Our systematic literature review identified 14 different semiquantitative or qualitative radiologic criteria that are used for the diagnosis of LSS; however, these criteria show remarkable variability in terms of their exact individual definitions and intra- and interrater reliability.

CT metal artefact reduction for internal fixation of the proximal humerus: Value of mono-energetic extrapolation from dual-energy and iterative reconstructions

AIM To assess the value of dual-energy computed tomography (DECT) and an iterative frequency split-normalized metal artefact reduction (IFS-MAR) algorithm compared to filtered back projections (FBP) from single-energy CT (SECT) for artefact reduction in internally fixated humeral fractures. MATERIALS AND METHODS Six internally fixated cadaveric humeri were examined using SECT and DECT. Data were reconstructed using FBP, IFS-MAR, and mono-energetic DECT extrapolations. Image analysis included radiodensity values and qualitative evaluation of artefacts, image quality, and level of confidence for localizing screw tips. RESULTS Radiodensity values of streak artefacts were significantly different (p < 0.05) between FBP (-104 ± 222) and IFS-MAR (73 ± 122), and between FBP and DECT (32 ± 151), without differences between IFS-MAR and DECT (p < 0.553). Compared to FBP, qualitative artefacts were significantly reduced using IFS-MAR (p < 0.001) and DECT (p < 0.05), without significant differences between IFS-MAR and DECT (p < 0.219). Image quality significantly (p = 0.016) improved for IFS-MAR and DECT compared to FBP, without significant differences between IFS-MAR and DECT (p < 0.553). The level of confidence for screw tip localization was assessed as best for DECT in all cases. CONCLUSION Both IFS-MAR in SECT and mono-energetic DECT produce improved image quality and a reduction of metal artefacts. Screw tip positions can be most confidently assessed using DECT.

In vitro high-resolution flat-panel computed tomographic arthrography for artificial cartilage defect detection: comparison with multidetector computed tomography.

ObjectivesThe objectives of this study were to analyze the spatial resolution of different reconstruction kernels and acquisition protocols, including a prototypic high-resolution protocol in flat-panel (FP) and multidetector (MD) computed tomography (CT), and to evaluate contrast and artificial cartilage depiction quality of in vitro FPCT and MDCT arthrography. Materials and MethodsAn image-quality cone beam phantom was used to compare resolution and different reconstruction kernels of the standard MDCT (120 and 80 kV) and the standard binned (2 × 2) and prototypic high-resolution unbinned (1 × 1) FPCT protocols (5- and 20-second runs each). With the resulting FPCT kernel best matching the standard MDCT kernel (U90u), artificial joint phantoms with differently sized groups of cartilage defects (2, 1, 0.5, and 0.3 mm in width) were then scanned using intra-articular iodinated contrast at 50 mgI/mL. In these joint phantoms, CT numbers and noise in the iodinated contrast and artificial cartilage tissue were measured and contrast-to-noise ratios (CNR) were calculated. Depiction quality of artificial cartilage defects was qualitatively rated by 2 independent radiologists. ResultsA sharp reconstruction kernel for all FPCT protocols suited best for matched resolution to the standard MDCT kernel. High-resolution 20-second 1 × 1 binning FPCT showed comparable resolution with MDCT in the range of 0.4 to 1.6 line pairs (lp) per millimeter with superior resolution in higher frequencies than 1.6 lp per millimeter (P < 0.001). Flat-panel computed tomographic 5-second runs were associated with higher image noise than the 20-second runs were. The CNR differed significantly among the protocols (P < 0.01) and was the highest in the 20-second FPCT, followed by the 5-second FPCT 2 × 2 and MDCT protocols. Interreader agreement for the depiction quality of artificial cartilage defects was substantial and high in the joint phantoms (0.74 and 0.81, respectively; P < 0.001). The best ratings of the artificial cartilage defect depiction quality were seen in the FPCT 20-second, followed by the FPCT 5-second and MDCT acquisitions. The depiction quality of smaller cartilage defects (1.0 and 1.67 lp per millimeter) was rated worst in the MDCT acquisitions. ConclusionsIn vitro FPCT arthrography offers superior CNR and artificial cartilage defect depiction quality to MDCT, and spatial resolution for small structures is higher when applying high-resolution acquisition protocols. Flat-panel computed tomography, thus, has the potential to improve workflow, and tailored high-resolution protocols may allow for advanced cartilage evaluation in CT arthrography.

Clinical outcome in lumbar decompression surgery for spinal canal stenosis in the aged population: a prospective Swiss multicenter cohort study.

Study Design. This is a prospective, multicenter cohort study including 8 medical centers in the metropolitan area of the Canton Zurich, Switzerland. Objectives. To examine whether outcome and quality of life might improve after decompression surgery for degenerative lumbar spinal stenosis (DLSS) even in patients older than 80 years and to compare data with a younger patient population from our own patient collective. Summary and Background Data. Lumbar decompression surgery without fusion has been shown to improve quality of life in lumbar spinal canal stenosis. In the population older than 80 years, treatment recommendations for DLSS show conflicting results. Methods. Eight centers in the metropolitan area of Zurich, Switzerland agreed on the classification of DLSS, surgical principles, and follow-up protocols. Patients were followed from baseline, at 6 months, and 12 months. Baseline characteristics were analyzed with 5 different questionnaires “Spinal Stenosis Measure, Feeling Thermometer, Numeric Rating Scale, 5D-3L, and Roland and Morris Disability Questionnaire.” In addition, our study population was compared with a younger control group. Furthermore, we calculated the minimal clinically important differences. Results. Thirty-seven patients with an average age of 82.5 ± 2.5 years reached the 12-month follow-up. Spinal Stenosis Measure scores, the Feeling Thermometer, the Numeric Rating Scale, and the Roland and Morris Disability Questionnaire showed significant improvements at the 6-month and 12-month follow-ups (P < 0.001). One EQ-5D-3Lsubgroup “anxiety/depression” showed no significant improvement (P = 0.109) at 12-month follow-up. The minimal clinically important difference for the “Symptom Severity scale” in the Spinal Stenosis Measure was achieved with improvement of 70% in the older patient population. Conclusion. Patients 80 years or older can expect a clinically meaningful improvement after lumbar decompression for symptomatic DLSS. Our patient population showed significant positive development in quality of life in the short- and long-term follow-ups. Level of Evidence: 3

How many radiographs are needed to detect angular stable head screw cut outs of the proximal humerus - A cadaver study

INTRODUCTION Cut out of locking head screws is the most common complication of locking plates in fracture fixation of the proximal humerus with potentially disastrous consequences. Aim of the study was to find the single best and combination of radiographic projections to reliably detect screw cut outs. MATERIALS AND METHODS The locking plate was fixed to six cadaveric proximal humeri. Six different radiographs were performed: anteriorposterior in internal (apIR), in neutral (ap0) and in 30° external rotation (apER); axial in 30° (ax30) and 60° (ax60) abduction and an outlet view. Each head screw (n=9) was sequentially exchanged to perforate the humeral head with the tip and all radiographs were repeated for each cut out. Randomized image reading by two blinded examiners for cut out was done for single projection and combinations. RESULTS Interrater agreement was 0.72-0.93. Best single projection was ax30 (sensitivity 76%) and the worst was the outlet view (sens. 17%). Standard combination of apIR/outlet reached a sens. of 54%. The best combination of two was: apER/ax30 (90% sens.), of three: apIR/apER/ax30 (96% sens.) and of four: apIR/ap0/apER/ax30 (100% sens.). CONCLUSION Standard radiographs (ap/outlet), especially in internal rotation, may miss nearly half of screw cut outs. Single best radiographic projection was an axial view with 30° abduction. To account for all cut outs and correct screw position a combination of four projections was needed. These simple and feasible intraoperative and postoperative radiographs help to detect screw perforations of the locking plate reliably. LEVEL OF EVIDENCE I (Study of Diagnostic Test).

Pitfalls in post-mortem CT-angiography – intravascular contrast induces post-mortem pericardial effusion

We present a case where multi-phase post-mortem computed tomography angiography (PMCTA) induced a hemorrhagic pericardial effusion during the venous phase of angiography. Post-mortem non-contrast CT (PMCT) suggested the presence of a ruptured aortic dissection. This diagnosis was confirmed by PMCTA after pressure controlled arterial injection of contrast. During the second phase of multi-phase PMCTA the presence of contrast leakage from the inferior cava vein into the pericardial sac was noted. Autopsy confirmed the post-mortem nature of this vascular tear. This case teaches us an important lesson: it underlines the necessity to critically analyze PMCT and PMCTA images in order to distinguish between artifacts, true pathologies and iatrogenic findings. In cases with ambiguous findings such as the case reported here, correlation of imaging findings with autopsy is elementary.

Is There an Association Between Pain and Magnetic Resonance Imaging Parameters in Patients With Lumbar Spinal Stenosis

Study Design. A prospective multicenter cohort study. Objective. The aim of this study was to identify an association between pain and magnetic resonance imaging (MRI) parameters in patients with lumbar spinal stenosis (LSS). Summary of Background Data. At present, the relationship between abnormal MRI findings and pain in patients with LSS is still unclear. Methods. First, we conducted a systematic literature search. We identified relationships of relevant MRI parameters and pain in patients with LSS. Second, we addressed the study question with a thorough descriptive and graphical analysis to establish a relationship between MRI parameters and pain using data of the LSS outcome study (LSOS). Results. In the systematic review including four papers about the associations between radiological findings in the MRI and pain, the authors of two articles reported no association and two of them did. Of the latters, only one study found a moderate correlation between leg pain measured by Visual Analog Scale (VAS) and the degree of stenosis assessed by spine surgeons. In the data of the LSOS study, we could not identify a relevant association between any of the MRI parameters and buttock, leg, and back pain, quantified by the Spinal Stenosis Measure (SSM) and the Numeric Rating Scale (NRS). Even by restricting the analysis to the level of the lumbar spine with the most prominent radiological “stenosis,” no relevant association could be shown. Conclusion. Despite a thorough analysis of the data, we were not able to prove any correlation between radiological findings (MRI) and the severity of pain. There is a need for innovative “methods/techniques” to learn more about the causal relationship between radiological findings and the patients’ pain-related complaints. Level of Evidence: 2