B Meyer

Visualization of Hypervascular Liver Lesions During TACE: Comparison of Angiographic C-Arm CT and MDCT

OBJECTIVE The purpose of our study was to evaluate the diagnostic accuracy and scan coverage of flat-detector C-arm CT compared with that of biphasic MDCT for depicting malignant hepatic lesions in patients with hypervascular liver tumors before they undergo transarterial chemoembolization (TACE). MATERIALS AND METHODS Fifteen patients with either hepatocellular carcinoma (HCC, n = 8) or hypervascular liver metastases from uveal melanoma (n = 7) underwent arterial and portal venous C-arm CT of the liver using intraarterial contrast media administration directly before TACE. The number and location of their hepatic malignancies were compared with those on MDCT. The scan coverage was documented and the liver diameter measured on MDCT. RESULTS Compared with MDCT, the sensitivity and specificity for segmental tumor involvement were 97% (76/78) and 85% (28/33), respectively, for reader 1, and 99% (77/78) and 79% (24/29), respectively, for reader 2. Complete scan coverage of the liver was obtained in five of the 15 patients with C-arm CT. In patients with incomplete scan coverage on C-arm CT, the craniocaudal liver diameter was significantly larger than in those patients with complete scan coverage (mean [95% CI], 22.7 [19.5-25.9] cm vs 20.2 [15.4-25.0] cm, p = 0.0193). CONCLUSION Biphasic arterial and portal venous C-arm CT showed a high sensitivity for the detection of malignant liver lesions. However, the liver could not be visualized completely in two thirds of the patients. Therefore, the current scan range limitations need to be overcome to make C-arm CT a valuable adjunct to MDCT for preprocedure evaluation and postprocedure follow-up imaging.

Dual energy CT of peripheral arteries: Effect of automatic bone and plaque removal on image quality and grading of stenoses

PURPOSE To evaluate the effect of automatic bone and plaque removal on image quality and grading of steno-occlusive lesions in patients undergoing dual energy CT angiography (CTA) of lower extremity. MATERIALS AND METHODS Dual energy (DE) runoff CTA was performed in 50 patients using the following parameters: collimation 2 x 32 x 0.6; tube potentials, 80 kV and 140 kV; reconstructed slice thickness 1mm. 100 mL iomeprol 400 and 50 mL saline were injected at 4 mL/s. Separate datasets were calculated for each of the two tubes and used to generate automatically bone-subtracted images (ABS) as well as bone and plaque subtracted images (ABPS). Residual bone in the ABS dataset was removed manually (=ABS-B dataset). In addition, a weighted average dataset from both dual energy acquisitions resembling a routine 120 kV CT acquisition was used for standard manual bone subtraction (MBS). Operator time for bone removal was measured. Effectiveness of bone subtraction and presence of vessel erosions was assessed by two readers in consensus. Stenosis grading in plaque subtracted and unsubtracted images was assessed and correlated. RESULTS Residual bone fragments (ribs: 46%, patella: 25%, spine: 4%, pelvis: 2%, tibia 2% of patients) were only observed with ABS. The time needed to manually remove these residual bones was 2.1+/-1.1 min and was significantly lower than the duration of manual bone removal (6.8+/-2.0 min, p<0.0001, paired t-test). A total of 1159 arteries were analyzed. Compromising vessel erosions were observed less frequently in the ABS-B dataset (10.6%) than in the MBS dataset (15.2%, p<0.001, wilcoxons signed rank test). A total of 817 steno-occlusive lesions were assessed. While the agreement of grading of steno-occlusive lesions was good at the levels of the aorta and the pelvic arteries (kappa=0.70 in both, Cohens kappa statistics), it was moderate at the level of the thigh arteries (kappa=0.57) and poor at the level of the calf (kappa=0.16). CONCLUSION DE CTA has substantial advantages over conventional CTA. Automatic bone subtraction is more time efficient and reliable. Automatic plaque subtraction for the first time provides a true CTA-luminogram which is easy to interpret and reduces the need for further post-processing. DE CTA provides best results in arteries of the thigh; below the knee, plaque subtraction is less accurate.

MRI of the thorax during whole-body MRI: evaluation of different MR sequences and comparison to thoracic multidetector computed tomography (MDCT).

To evaluate the accuracy of four MR sequences used as part of a whole‐body MRI protocol to detect pulmonary lesions in cancer patients.

The value of combined soft-tissue and vessel visualisation before transarterial chemoembolisation of the liver using C-arm computed tomography

The purpose of the study was to prospectively evaluate intrahepatic vessel depiction on C-arm CT (CACT) and the influence of the additional combined tissue and three-dimensional vessel visualisation on the positioning of the TACE catheter in comparison to DSA alone. Thirty consecutive patients scheduled for their first transarterial chemoembolisation underwent biphasic CACT and DSA of the liver. After assessing the DSA images for procedure planning, the CACT images were reviewed. The number and origin of the tumour-feeding arteries and the ideal position of the catheter for TACE on both DSA and CACT were assessed and correlated. The number of vessels identified as tumour feeders in each patient was significantly higher using additional CACT than on DSA alone (CACT: 4.0 ± 1.7; DSA: 3.3 ± 1.4; P = 0.003, t-test). After considering CACT, in 50% of the patients the catheter position was changed for TACE. Segmental portal vein thrombosis was seen in three patients on CACT, but in only one on DSA. As CACT depicts soft tissue and small vessels with high spatial resolution, tumour vessel allocation is facilitated, and ideal catheter position for TACE can be more accurately identified. The high impact of CACT on the TACE procedure suggests the benefits of its routine use for all patients undergoing their first TACE.

Do the cardiovascular risk profile and the degree of arterial wall calcification influence the performance of MDCT angiography of lower extremity arteries

ObjectivesTo 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.MethodsIn 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).ResultsThe 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 ≥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.ConclusionsPatients with diabetes and renal failure should be considered as candidates for alternative vessel imaging in order to avoid inconclusive examination results.

Diagnostic confidence of run-off CT-angiography as the primary diagnostic imaging modality in patients presenting with acute or chronic peripheral arterial disease.

Objectives To investigate the reliability of CT-angiography of the lower extremities (run-off CTA) to derive a treatment decision in patients with acute and chronic peripheral artery disease (PAD). Materials and Methods 314 patients referred for run-off CTA were includ-ed in this retrospective study. First, diagnostic confidence of run-off CTA to derive a treat-ment decision was assessed in an interdisciplinary vascular conference using a 2 point scale (sufficient or not sufficient diagnostic confidence) and compared with the image quality eval-uated by two readers in consensus in four different levels (abdominopelvic, thigh, calf, foot arteries). Second, reliability of treatment decision was verified in all patients undergoing re-vascularization therapy. Results Diagnostic confidence of run-off CTA to derive a treatment deci-sion was sufficient in all patients with acute and in 97% of patients (215/221) with chronic PAD, whereas the rate of run-off CTA with non-diagnostic image quality was considerably higher in the calf and foot level (acute vs. chronic; calf: 28% vs.17%; foot: 52% vs. 20%). Reliability of treatment decision was superior for patients with chronic (123/133 = 92%) than for patients with acute PAD (64/78 = 82%, P = 0.02). Conclusion Run-off CTA is a reliable imaging modality for primary diag-nostic work-up of patients with acute and chronic PAD.

[Flat-detector CT-based electromagnetic navigation].

ZusammenfassungMit der Flachdetektor-CT (FD-CT) am Angiographiegerät steht zur Intervention eine bildgebende Technik zur Verfügung, die zur elektromagnetischen Navigation im Rahmen perkutaner Punktionen genutzt werden kann. Der vorliegende Beitrag stellt die Funktionsweise eines elektromagnetischen Navigationssystems dar und erläutert den Ablauf einer elektromagnetisch navigierten Punktion und die Einsatzmöglichkeiten eines solchen Systems in der klinischen Praxis.AbstractFlat-detector CT coupled to an angiography device provides an imaging technique for interventions which can be used for electromagnetically navigated percutaneous punctures. This report explains the functionality of an electromagnetic navigation system and describes the course of an electromagnetically navigated puncture and the capabilities of such a system in the clinical routine.

Chronisch thromboembolische pulmonale Hypertonie: Diagnostischer Zugewinn durch C-Arm CT im Vergleich zur digitalen Subtraktionsangiografie

Material und Methodik: Retrospektive Analyse von 143 konsekutiven Patienten mit dem klinischen Verdacht einer Lungenarterienembolie untersucht in 3 verschiedenen Computertomographen in der klinischen Routine. Das Bolus tracking erfolgte mit 120 Hounsfield-Einheiten (HU) Grenzwert und Region of interest (ROI) im Truncus pulmonalis (Gruppe A, n=70) bzw. zur Verzögerung des Untersuchungsbeginns in der Aorta descendens (Gruppe B, n=73). Die Kontrastmitttelmenge betrug 70 bis 120 ml Iomeprol 300. Mit dem t-Test wurde die erreichte Dichte im Truncus pulmonalis verglichen. Weiterhin erfolgte eine Regressionsanalyse möglicher Begleitfaktoren.

C-Arm CT – An Adjunct to DSA for Endoleak Classification in Patients with Endovascular Repair of Abdominal Aortic Aneurysms

PURPOSE To assess the benefit of C-arm CT for classification and procedural guidance during interventional therapy of endoleaks (EL) after endovascular repair (EVAR) of abdominal aortic aneurysms (AAA). MATERIALS AND METHODS 12 patients with EL diagnosed with CT but undetermined EL classification (ELC) underwent DSA and transarterial contrast-enhanced C-arm CT. ELC (based on DSA, C-arm CT and CT) assessed during the angiographic procedure served as the standard of reference (SOR). Subsequently, ELC was assessed by a blinded second reader based on DSA or C-arm CT and compared to the SOR. In the case of an interventional procedure (n = 6), the added value of C-arm CT for procedure guidance was assessed retrospectively (1: essential, 2: helpful, 3: additional information without impact, 4: no additional information). RESULTS The blinded reader classified 9/12 EL using DSA alone and 11/12 EL using C-arm CT alone. In one patient, the temporal resolution provided by DSA was essential to establish the diagnosis. In 6 patients, a type 2 EL without need for therapy was diagnosed. The remaining 6 patients showed EL that were treated immediately (type 1 EL, n = 4: 3 stent graft extensions and one angioplasty; type 2 EL, n = 1: translumbar embolization; type 3 EL, n = 1: sealing of a fabric tear). The information provided by C-arm CT was assessed to be essential in three patients and helpful in two. CONCLUSION C-arm CT is an ideal adjunct to DSA. In our pilot study, it helped to localize and classify endoleaks more reliably than DSA alone.

Hybride Multi-Resolutions k-Raum Nachbearbeitung für Gadofosveset-verstärkte hochaufgelöste arterielle periphere MR-Angiographie

Periphere MR-Angiographien mit hoher ortlicher Aufl osung und arteriellem Kontrast wurden mit einer vor kurzem vorgestellten Computer-Methode erzeugt. Steady-State und First-Pass MRAngiographien der Unterschenkel von 10 Patienten wurden zu hoch aufgel osten arteriellen MR-Angiographien kombiniert. Die Bildqualitat wurde sehr gut bewertet. Die Ergebnisse einer Befundung von Stenosen waren sehr nah an denen der Steady-State MR Angiographien, die den Standard darstellten.