Christoph Dueber

MR angiography of the pedal arteries with gadobenate dimeglumine, a contrast agent with increased relaxivity, and comparison with selective intraarterial DSA

To compare gadobenate dimeglumine (Gd‐BOPTA)–enhanced MR angiography (i.e., contrast‐enhanced MRA [CE‐MRA]) of the pedal vasculature with selective digital subtraction angiography (DSA) in patients with peripheral arterial occlusive disease (PAOD).

Endovascular treatment of acute bleeding complications in traumatic aortic rupture and aortobronchial fistula.

OBJECTIVE Herein we report our experience in placement of endovascular stentgrafts in the descending aorta in patients with acute bleeding complications due to traumatic rupture or aortobronchial fistula. METHODS Six patients (one woman, five men, mean age 47+/-19 years) were treated from September 1995 to February 2000 by implantation of endovascular stentgrafts in the descending aorta. Indications included traumatic ruptures of the aortic isthmus (n=3) and aortobronchial fistulas (n=3). All procedures were performed under general anaesthesia. The implants were introduced under fluoroscopic guidance via the aorta (n=1), the iliac (n=4) or femoral (n=2) artery, respectively. RESULTS All aortobronchial fistulas and ruptures were sealed up successfully. There was no perioperative morbidity and no procedure-related morbidity except one patient who received aortofemoral reconstruction because of iliac occlusive disease. All patients are alive and well after a mean follow-up of 31 months (range 6-60). Two patients had recurrent hemoptysis, in one case, the patient received a second implant (distal extension), the other patient was managed conservatively. CONCLUSION Endovascular treatment by a stentgraft is a safe and reliable procedure in the management of acute bleeding complications in patients with aortic rupture or aortobronchial fistulas.

Subcutaneous implantation metastasis of a cholangiocarcinoma of the bile duct after percutaneous transhepatic biliary drainage (PTBD)

Abstract Percutaneous transhepatic biliary drainage (PTBD) is the basis for most biliary interventional procedures. We recently observed the occurrence of a subcutaneous implantation metastasis after PTBD in a patient with incurable cholangiocarcinoma. Although tumor cell seeding along the catheter tract is a very rare complication, we think that PTBD should be avoided when curative resection is planned.

Radiation exposure in CT-guided interventions

PURPOSE To investigate radiation exposure in computed tomography (CT)-guided interventions, to establish reference levels for exposure, and to discuss strategies for dose reduction. MATERIALS AND METHODS We analyzed 1576 consecutive CT-guided procedures in 1284 patients performed over 4.5 years, including drainage placements; biopsies of different organs; radiofrequency and microwave ablations (RFA/MWA) of liver, bone, and lung tumors; pain blockages, and vertebroplasties. Data were analyzed with respect to scanner settings, overall radiation doses, and individual doses of planning CT series, CT intervention, and control CT series. RESULTS Eighty-five percent of the total radiation dose was applied during the pre- and post-interventional CT series, leaving only 15% applied by the CT-guided intervention itself. Single slice acquisition was associated with lower doses than continuous CT-fluoroscopy (37 mGy cm vs. 153 mGy cm, p<0.001). The third quartile of radiation doses varied considerably for different interventions. The highest doses were observed in complex interventions like RFA/MWA of the liver, followed by vertebroplasty and RFA/MWA of the lung. CONCLUSIONS This paper suggests preliminary reference levels for various intervention types and discusses strategies for dose reduction. A multicenter registry of radiation exposure including a broader spectrum of scanners and intervention types is needed to develop definitive reference levels.

Noninvasive Assessment of Pulmonary Hemodynamics in Patients With Chronic Thromboembolic Pulmonary Hypertension by High Temporal Resolution Phase-Contrast MRI Correlation With Simultaneous Invasive Pressure Recordings*

Background— Right heart catheterization is the gold standard for assessment of pulmonary hemodynamics in patients with chronic thromboembolic pulmonary hypertension. To date, MRI has not been able to produce precise measurements of mean pulmonary arterial pressure (mPAP). The purpose of the study was to create a model for estimating mPAP and pulmonary vascular resistance in patients with chronic thromboembolic pulmonary hypertension by high temporal resolution phase-contrast MRI (PC-MRI) and to correlate the results with simultaneously acquired, invasive catheter-based measurements (simultaneously measured mPAP) and with right heart catheterization measurements. Methods and Results— A total of 19 patients with chronic thromboembolic pulmonary hypertension underwent right heart catheterization and—after digital subtraction angiography of the pulmonary arteries—subsequent PC-MRI at 1.5 T with simultaneous recording of mPAP. Velocity– and flow–time curves of PC-MRI were used to calculate absolute acceleration time (Ata), maximum of mean velocities (MV), volume of acceleration (AV), and maximum flow acceleration (dQ/dt). On the basis of these parameters, multiple linear regression analysis revealed maximum achievable model fit (B=0.902) for the following linear combination equation to calculate mPAP (mPAP_cal): mPAP_cal=69.446−(0.521×Ata)−(0.570×MV)+(1.507×AV)+(0.002×dQ/dt). There was a statistically significant equivalence of mPAP_cal and simultaneously measured mPAP with a goodness of fit of 0.892. Pulmonary vascular resistance was overestimated by calculated pulmonary vascular resistance on the basis of PC-MRI in comparison with right heart catheterization–based measurements by a median of −112 dyn·s·cm−5, the pairwise regression formula revealed a goodness of fit of 0.792. Conclusions— PC-MRI–derived parameters enable noninvasive assessment of pulmonary hemodynamics in patients with chronic thromboembolic pulmonary hypertension.

Percutaneous Treatment of Hepatocellular Carcinoma in Patients with Transjugular Intrahepatic Portosystemic Shunts

PurposeTo assess the role of transcatheter arterial chemoembolization (TACE) and percutaneous ethanol injection (PEI) in patients with hepatocellular carcinoma (HCC) and transjugular intrahepatic portosystemic shunts (TIPS).MethodsBetween January 1999 and September 2004, 6 patients with HCC and TIPS were treated with either TACE (n = 3) or TACE in combination with PEI (n = 3). One patient had a known advanced, untreated HCC prior to TIPS. In the remaining 5 patients HCC was diagnosed 14, 17, 51, 69, and 76 months respectively after elective TIPS. TACE was performed using a mixture of 30–60 mg of epirubicin and 10 ml of lipiodol following superselective catheterization of tumor-feeding vessels. PEI was performed under CT guidance.MethodsThe mean follow-up time after treatment of HCC was 26.2 months (range 7–46 months). During follow-up, all patients were free of rebleeding. Two patients died 7 and 38 months after one session of TACE and PEI (77 months after TIPS) and three sessions of TACE (91 months after TIPS), respectively. The cause of death was liver failure (Child-Pugh class C) and peritonitis, respectively. A third patient underwent liver transplantation 24 months after TIPS and several sessions of TACE. In the remaining 3 patients, the HCC is well controlled 13, 30, and 46 months after repetitive percutaneous treatment without signs of hepatic deterioration or metastasis.ConclusionTranscatheter arterial superselective chemoembolization and percutaneous ethanol injection seems to be beneficial even in HCC patients treated with TIPS, provided that the liver function is adequate.

Aneurysms complicating inflammatory diseases in immunocompromised hosts: value of contrast-enhanced CT

Abstract. We studied the value of contrast-enhanced CT in the detection of aneurysms in immunocompromised patients suffering from inflammatory diseases eventually complicated by hemorrhage. Contrast-enhanced spiral CT was applied in three patients with immunocompromise due to chemotherapy, alcohol abuse or HIV. They suffered from invasive aspergillosis, chronic pancreatitis with pseudocyst formation, and acute pancreatitis together with HIV-associated lymphadenopathy. Complicating hemorrhage was present in two cases. Contrast-enhanced CT showed aneurysms complicating the underlying inflammatory disease in all three cases. The feeding vessels were identified and the patients with signs of bleeding were subsequently referred for angiography and embolization. Contrast-enhanced spiral CT is suited to detect aneurysms in immunocompromised patients suffering from inflammatory disease. It is recommended in these patients prior to angiography and intervention.

Midterm follow-up after DC-BEAD™-TACE of Hepatocellular Carcinoma (HCC)

AIM To determine local response, its predictors and survival and complication rates after DC-Bead™-TACE in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS DC-Beads™ are non-resorbable, polyvinyl-alcoholic hydrophilic microspheres. They release high amounts of chemotherapeutics directly into the tumour. Delivery is sustained over time, tumour feeders are embolised. We used beads from 100-300 to 500-700 μm loaded with Doxorubicin (max. 150 mg/4ml). Fifty patients (mean age: 68.5 ± 8.8 years) with HCC were analysed. DC-Bead™-TACE was performed once or repeated in two-month intervals. Imaging scans (CT or MRI) were done one-month following each procedure. To evaluate tumour response EASL and RECIST criteria was applied. If eligible, every patient received a non-selective TACE. RESULTS 128 DC-Bead™ sessions were performed: 127 showed technical success, 120 successful stasis. Complications occurred in 7% (9/128): active bleeding into the tumour (n=1), liver failure (n=1), liver abscess (n=1) ascites (n=3), pleural effusion (n=1), false aneurysm (n=1) and hypoglycaemia (n=1). At imaging after the 1st, 2nd, 3rd and 4th-8th session, objective response (complete+partial) was 49%, 67%, 67% and 31%, progressive disease was seen in n=11/50. Baseline diameter and differentiation significantly impacted response. Median overall survival was 25.1 months (95% [CI]: 18.3-31.9) with an estimated cumulative survival rate at one and two-to-four years of 66.7% and 45.7%, respectively. CONCLUSION DC-Beads™ can be safely and effectively control HCC. Survival and response rates are encouraging, complications are low. Many factors are involved in response to treatment like liver function or child state.

Influence of pixel size on quantification of airway wall thickness in computed tomography.

Objectives: The purpose of this study was to determine the point where a further decrease in voxel size does not result in better automatic quantification of the bronchial wall thickness by using 2 different assessment techniques. Materials and Methods: The results from the commonly used full-width-at-half-maximum (FWHM) principle and a new technique (integral-based method [IBM]) were compared for thin-section multidetector computed tomography (MDCT) data sets from an airway phantom containing 10 different tubular airway phantoms and in a human subsegmental bronchus in vivo. Correlation with the actual wall thickness and comparison of the wall thicknesses assessed for different voxel sizes were performed, and the image resolutions were also compared subjectively. Results: The relative error ranged from 0% (biggest phantom) to 330% (smallest phantom, biggest field of view, smaller matrix, and FWHM). Using IBM, the maximum relative error was 10% in the same setting. For FWHM, the improvement was marginal for most settings with a pixel spacing less than 0.195 × 0.195 × 0.8 mm; however, it still decreases the relative error from 290% to 273.6% for a wall thickness of 0.3 mm and a pixel spacing of 0.076 × 0.076 × 0.8 mm. Conclusions: (1) Using a special technique such as IBM to account for computed tomographys blurring effect in assessing airway wall thickness had the greatest impact on correct quantification. (2) The visual impression and the automatic quantification using the FWHM technique improved marginally by decreasing the voxel size to less than 0.195 × 0.195 × 0.8 mm. (3) The FWHM technique as a model for visual quantification is not reliable for airway wall thicknesses less than 1.5 mm.

Development of an IHE MRRT-compliant open-source web-based reporting platform

AbstractObjectivesTo develop a platform that uses structured reporting templates according to the IHE Management of Radiology Report Templates (MRRT) profile, and to implement this platform into clinical routine.MethodsThe reporting platform uses standard web technologies (HTML / JavaScript and PHP / MySQL) only. Several freely available external libraries were used to simplify the programming. The platform runs on a standard web server, connects with the radiology information system (RIS) and PACS, and is easily accessible via a standard web browser.ResultsA prototype platform that allows structured reporting to be easily incorporated into the clinical routine was developed and successfully tested. To date, 797 reports were generated using IHE MRRT-compliant templates (many of them downloaded from the RSNA’s radreport.org website). Reports are stored in a MySQL database and are easily accessible for further analyses.ConclusionDevelopment of an IHE MRRT-compliant platform for structured reporting is feasible using only standard web technologies. All source code will be made available upon request under a free license, and the participation of other institutions in further development is welcome.Key Points• A platform for structured reporting using IHE MRRT-compliant templates is presented. • Incorporating structured reporting into clinical routine is feasible. • Full source code will be provided upon request under a free license.