Transpedicular screw fixation has been accepted worldwide since Harrington et al. first placed pedicle screws through the isthmus. In vivo and in vitro studies indicated that pedicle screw insertion accuracy could be significantly improved with image-assisted systems compared with conventional approaches. The O-arm is a new generation intraoperative imaging system designed without compromise to address the needs of a modern OR like no other system currently available. The aim of our study was to check the accuracy of O-arm based and S7-navigated pedicle screw implants in comparison to free-hand technique described by Roy-Camille at the lumbar and sacral spine using CT scans. The material of this study was divided into two groups, free-hand group (group I) (30 patients; 152 screws) and O-arm group (37 patients; 187 screws). The patients were operated upon from January to September 2009. Screw implantation was performed during PLIF or TLIF mainly for spondylolisthesis, osteochondritis and post-laminectomy syndrome. The accuracy rate in our work was 94.1% in the free-hand group compared to 99% in the O-arm navigated group. Thus it was concluded that free-hand technique will only be safe and accurate when it is in the hands of an experienced surgeon and the accuracy of screw placement with O-arm can reach 100%.

Introduction Although pedicle screw fixation is a wellestablished technique for the lumbar spine, screw placement in the thoracic spine is more challenging because of the smaller pedicle size and more complex 3D anatomy. The intraoperative use of image guidance devices may allow surgeons a safer, more accurate method for placing thoracic pedicle screws while limiting radiation exposure. This generic 3D imaging technique is a new generation intraoperative CT imaging system designed without compromise to address the needs of a modern OR. Aim The aim of our study was to check the accuracy of this generic 3D navigated pedicle screw implants in comparison to free hand technique described by Roy-Camille at the thoracic spine using CT scans. Material and methods The material of this study was divided into two groups: free hand group (group I) (18 patients; 108 screws) and 3D group (27 patients; 100 screws). The patients were operated upon from January 2009 to March 2010. Screw implantation was performed during internal fixation for fractures, tumors, and spondylodiscitis of the thoracic spine as well as for degenerative lumbar scoliosis. Results The accuracy rate in our work was 89.8 % in the free hand group compared to 98 % in the generic 3D navigated group. Conclusion In conclusion, 3D navigation-assisted pedicle screw placement is superior to free hand technique in the thoracic spine.

BackgroundIntramyocardial haemorrhage (IMH) and microvascular obstruction (MVO) represent reperfusion injury after reperfused ST-elevation myocardial infarction (STEMI) with prognostic impact and “hypointense core” (HIC) appearance in T2-weighted images. We aimed to distinguish between IMH and MVO by using T2*-weighted cardiovascular magnetic resonance imaging (CMR) and analysed influencing factors for IMH development.Methods and resultsA total of 151 patients with acute STEMI underwent CMR after primary angioplasty. T2-STIR sequences were used to identify HIC, late gadolinium enhancement to visualise MVO and T2*-weighted sequences to detect IMH. IMH+/IMH− patients were compared considering infarct size, myocardial salvage, thrombolysis in myocardial infarction (TIMI) flow, reperfusion time, ventricular volumes, function and pre-interventional medication. Seventy-six patients (50 %) were IMH+, 82 (54 %) demonstrated HIC and 100 (66 %) MVO. IMH was detectable without HIC in 16 %, without MVO in 5 % and HIC without MVO in 6 %. Multivariable analyses revealed that IMH was associated with significant lower left ventricular ejection fraction and myocardial salvage index, larger left ventricular volume and infarct size. Patients with TIMI flow grade ≤1 before angioplasty demonstrated IMH significantly more often.ConclusionsIMH is associated with impaired left ventricular function and higher infarct size. T2 and HIC imaging showed moderate agreement for IMH detection. T2* imaging might be the preferred CMR imaging method for comprehensive IMH assessment.Key Points• Intramyocardial haemorrhage is a common finding in patients with acute reperfused myocardial-infarction.• T2*imaging should be the preferred CMR method for assessment of intramyocardial haemorrhage.• Intramyocardial haemorrhage can be considered as an important influencing factor on patient’s outcome.

ObjectiveComparing the diagnostic value of multi-sequential cardiac magnetic resonance imaging (CMR) with endomyocardial biopsy (EMB) for sub-clinical cardiac allograft rejection.MethodsOne hundred and forty-six examinations in 73 patients (mean age 53 ± 12 years, 58 men) were performed using a 1.5 Tesla system and compared to EMB. Examinations included a STIR (short tau inversion recovery) sequence for calculation of edema ratio (ER), a T1-weighted spin-echo sequence for assessment of global relative enhancement (gRE), and inversion-recovery sequences to visualize late gadolinium enhancement (LGE). Histological grade ≥1B was considered relevant rejection.ResultsOne hundred and twenty-seven (127/146 = 87 %) EMBs demonstrated no or mild signs of rejection (grades ≤1A) and 19/146 (13 %) a relevant rejection (grade ≥1B). Sensitivity, specificity, positive predictive, and negative predictive values were as follows: ER: 63 %, 78 %, 30 %, and 93 %; gRE: 63 %, 70 %, 24 %, and 93 %; LGE: 68 %, 36 %, 13 %, and 87 %; with the combination of ER and gRE with at least one out of two positive: 84 %, 57 %, 23 %, and 96 %. ROC analysis revealed an area under the curve of 0.724 for ER and 0.659 for gRE.ConclusionCMR parameters for myocarditis are useful to detect sub-clinical acute cellular rejection after heart transplantation. Comparable results to myocarditis can be achieved with a combination of parameters.Key Points• Magnetic resonance imaging is useful for the assessment of cardiac allograft rejection.• CMR has a high negative predictive value for exclusion of allograft rejection.• Diagnostic performance is not yet good enough to replace endomyocardial biopsy.

Transcatheter aortic valve implantation (TAVI) is currently considered an acceptable alternative for the treatment of patients with severe aortic stenosis and a high perioperative risk or a contraindication for open surgery. The benefit of TAVI significantly outweighs the risk of the procedure in patients requiring treatment that are not suitable for open surgery, and leads to a lower mortality in the one-year follow-up.?The absence of a direct view of the aortic root and valve remains a challenge for the transcatheter approach. While direct inspection of the aortic valve during open surgery allows an adequate prosthesis choice, it is crucial for TAVI to know the individual anatomical details prior to the procedure in order to assure adequate planning of the procedure and proper prosthesis choice and patient selection. Among the imaging modalities available for the evaluation of patients prior to TAVI, computed tomography (CT) plays a central role in patient selection. CT reliably visualizes the dimensions of the aortic root and allows a proper choice of the prosthesis size. The morphology of the access path and relevant comorbidities can be assessed. The present review summarizes the current state of knowledge regarding the value of CT in the evaluation of patients prior to TAVI. Key Points: Citation Format: