C Ribbe

Charité Universitätsmedizin Berlin, Berlín, Berlin, Germany

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Publications (10)14.33 Total impact

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    ABSTRACT: To retrospectively assess the influence of arterial wall calcifications on the accuracy of run-off computed tomographic angiography (CTA) and to analyse whether cardiovascular risk factors are predictors of compromising calcifications. In 200 consecutive patients who underwent run-off CTA, calcifications were assessed in pelvic, thigh and calf arteries using a four-point scale. Fifty-nine patients with digital subtraction angiography (DSA) were assessed by both techniques to estimate a threshold of compromising calcifications, defined as a decrease of sensitivity, specificity, PPV or NPV below the lower 95% confidence interval of overall results. Regression analysis was performed to investigate a potential relationship between compromising calcifications and presence of cardiovascular risk factors, advanced patient age and severe peripheral arterial disease (PAD). The highest Ca(++)-score was chosen as the cut-off for the regression analysis, as a relevant decrease of specificity (0.91; overall: 0.95) above the knee and of sensitivity (0.66; overall: 0.83), specificity (0.65; overall: 0.93), positive predictive value (PPV) and negative predictive value (NPV) below the knee was observed. In the pelvic and thigh arteries, severe PAD (Fontaine Stage >or=III) showed the highest odds ratio for compromising calcifications (2.9), followed by diabetes mellitus (2.4), renal failure (2.1) and smoking (1.7). In the calf, renal failure (12.2) and diabetes mellitus (3.3) were the strongest predictors. Patients with diabetes and renal failure should be considered as candidates for alternative vessel imaging in order to avoid inconclusive examination results.
    European Radiology 09/2009; 20(2):497-505. · 4.34 Impact Factor
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    ABSTRACT: The influence of different table feeds (TF) on vascular enhancement and image quality in patients undergoing lower extremity runoff-CTA for peripheral artery occlusive disease (PAOD), acute ischemia (AI) or abdominal aortic aneurysm (AAA) with PAOD was investigated retrospectively. One hundred eighty-five patients (PAOD: n = 132; AI: n = 40; AAA: n = 13) underwent 16-detector runoff-CTA (120 kV; 140 mAs; rotation time 0.5 s, collimation 16 x 1.5 mm) using different TF (30 mm/s: n = 25; 40 mm/s: n = 91; 48 mm/s: n = 36; 56 mm/s: n = 33). Vascular enhancement of the large arteries was measured every 10 cm along the z-axis from the upper abdomen to the toe. Arterial enhancement in the distal lower leg was compared (ANOVA, Bonferroni post-test). Qualitative assessment of bolus timing was performed independently by two radiologists. The study was IRB approved. In patients with PAOD or AI, enhancement of calf arteries using a TF of 48 mm/s (278 +/- 79 HU) was significantly higher in comparison to two slower TF (30 mm/s: 201 +/- 70 HU, P < 0.001; 40 mm/s: 251 +/- 79 HU, P < 0.05; 56 mm/s: 261 +/- 57 HU, NS) and the fewest noninterpretable arterial segments below the knee were observed with a TF of 48 mm/s (reader 1: 5/121 = 4.1%; reader 2: 4/121 = 3.3%). In patients with AAA, the fewest nondiagnostic segments occurred with a TF of 30 mm/s (2/12 = 17%, both readers) and 40 mm/s (4/24 = 17%, both readers). A TF of 48 mm/s provided the best synchronization of CT data acquisition and contrast bolus propagation and thus the best image quality in patients with PAOD and AI. In patients with AAA, a slower TF of 30 mm/s provided better image quality than faster CT protocols.
    European Radiology 09/2008; 18(8):1546-55. · 4.34 Impact Factor
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    ABSTRACT: The objective of our study was to prospectively compare CT angiography (CTA) performed on a 16-MDCT scanner and digital subtraction angiography (DSA) in patients with peripheral arterial disease. CTA and DSA were compared in 50 patients. CTA was independently evaluated by two blinded observers. DSA was evaluated by two additional blinded observers in consensus. Consensus DSA served as the reference standard for comparisons with CTA in terms of diagnostic quality, grading of stenoocclusive lesions, visualization of collaterals, impact on patient management, and time required for analysis. No significant differences in diagnostic quality were observed between CTA and DSA above the ankle; both CTA observers noted significantly better visualization of pedal arteries (70 and 72 segments, respectively) than on DSA (57 segments). Of 958 stenoocclusive lesions on DSA, CTA observers 1 and 2 detected 933 and 929 lesions, respectively. Sensitivity and specificity for the detection of hemodynamically relevant (> 50%) lesions was 93.3% and 96.5% for observer 1 and 90.1% and 95.6% for observer 2. Collaterals were seen at 150 arterial levels on DSA compared with 97 and 92 levels on CTA (p < 0.05, both observers). Patient management decisions based on CTA were equivalent to those based on DSA in 49 of the 50 patients. CTA is an effective noninvasive alternative to DSA for the evaluation of peripheral arterial disease.
    American Journal of Roentgenology 10/2007; 189(3):702-11. · 2.90 Impact Factor
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2006; 178.
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    ABSTRACT: To assess the degree of enhancement and image quality of 16-slice multidetector CT angiography (MDCTA) of pelvic and lower limb arteries with a monophasic contrast medium injection protocol. Fifty patients underwent a CT angiography of the pelvic and lower limb arteries using the following parameters: collimation 16 x 1.5 mm, rotation time 0.5 s, table feed 40 mm/sec, slice thickness 2 mm, reconstruction interval 1.2 mm, 100 ml Iomeprol 400 + 60 ml normal saline, flow rate 4 ml/s, bolus tracking (threshold of 250 DeltaHU in aorta). Arterial enhancement was measured in all arterial segments. Maximum intensity projections (MIP) together with axial images were reviewed by two radiologists (consensus). If the results were inconclusive for stenosis, additional curved multiplanar reformations (MPR) were performed. The mean arterial enhancement values were aorta: 314 +/- 69, pelvis: 342 +/- 105, thigh: 347 +/- 139, calf: 231 +/- 109 DeltaHU. The image quality was judged as excellent in 346 (77.6 %), adequate in 76 (17 %), and inadequate in 24 (5.4 %, all but one in calf and foot) of 446 arterial territories. An override of the contrast bolus below the knee occurred in 2 patients rendering the calf arteries nondiagnostic. Venous enhancement occurred in 13 patients but this compromised the diagnostic assessment in only one case. Additional MPRs were required accurately to assess stenoses in 22 of 200 arterial levels in 16 patients with marked arterial calcifications. 16-slice MDCTA with a monophasic contrast bolus of Iomeprol 400 provided good arterial enhancement and diagnostic image quality in 94.6 % of the depicted arterial segments. The majority (67 %) of nondiagnostic segments were below the ankle. MPRs were required in patients with marked calcification for accurate assessment of stenosis.
    RöFo - Fortschritte auf dem Gebiet der R 12/2005; 177(11):1562-70. · 2.76 Impact Factor
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2005; 177.
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2005; 177(11):1562-1570.
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2005; 177.
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    ABSTRACT: PURPOSE To compare 16-slice multidetector-CTA and DSA in peripheral arteriography of the pelvis, leg and foot. METHOD AND MATERIALS CTA of peripheral arteries was performed in 28 patients using a Somatom Sensation 16 (Siemens, Germany). Collimation was 16 x 1.5 mm, rotation time 0.5 s, table feed 40mm/sec, slice thickness 2 mm, reconstruction interval 1.2 mm. 100 ml Iomeprol 400 (Bracco, Italy) were injected at 4 ml/s followed by 50 ml saline. Bolus tracking was used. DSA was performed within 4 weeks of CTA using 4F pigtail catheter and approx. 180 ml Iomeprol 300. CTA and DSA were independently read by blinded readers based on arterial segments (maximum of 25 per patient). Stenoses were classified on a 4 grade scale (I: < 50%, II: 50-75%, III: 76-99%, IV: occlusion). RESULTS A total of 436 vascular segments were analysed (several patients had only limited periinterventional DSA). 12 of these were not visualised on CTA (all below knee) and 28 segments were not seen on DSA (3 above and 25 below knee). A total of 446 stenoses/occlusions were seen on both modalities. Grading of these showed complete agreement between CTA and DSA in 77.4%, overestimation by CTA of 1� in 12.6%, underestimation (CTA) of 1� in 9.0%, overestimation (CTA) of > 1� in 0.7% and underestimation (CTA) > 1� in 0.4%. Compared to DSA as gold standard, sensitivity and specificity of CTA for detecting high grade stenoses (>75%) and occlusions was 91% and 96% respectively. Agreement between CTA and DSA was excellent (kappa: 0.89). CONCLUSIONS There was excellent agreement between CTA and DSA with regards to grading of stenoses with complete agreement in 77.4% of patients. Discrepancies of more than 1 grade occurred in only 1% of stenoses. CTA proved more sensitive than DSA in demonstrating small peripheral arteries with poor contrast filling.
    Radiological Society of North America 2004 Scientific Assembly and Annual Meeting; 12/2004
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2004; 176.