Niels Zorger

New real-time image fusion technique for characterization of tumor vascularisation and tumor perfusion of liver tumors with contrast-enhanced ultrasound, spiral CT or MRI: First results

AIM Evaluation and characterization of the vascularisation and perfusion of liver tumors by means of image fusion of dynamic contrast-enhanced ultrasound (CEUS), multidetector-CT (MD-CT) or magnetic resonance imaging (MRI) with the ultrasound navigation technique. MATERIAL For interventional planning a real-time image fusion involving CEUS (LOGIQ E9, GE) was performed in 20 patients (12 men, 8 women, age 43-69 years, median 54) with histologically confirmed malignant liver tumors (9 x hepatocellular carcinoma (HCC), 5 x metastases, 2 x hemangiomas, 1 x cholangiocellular carcinoma (CCC), 1 x lymphoma, 1 x neuroendocrine tumor, 1 x focal nodular hypoplasia (FNH)). In 17 patients the real-time CEUS was fused with contrast-enhanced MD-CT and in three patients with contrast-enhanced MRI (Gd-DTPA and liver-specific contrast medium Resovist. All of the ultrasound examinations were performed by an experienced examiner with a multi-frequency probe (2-5 MHz, LOGIQ E9, GE); dynamic image sequences up to 3 minutes in true agent detection mode of contrast harmonic imaging (CHI) were documented. An evaluation of the tumor was performed by the characterization of the dynamics of the contrast medium and microperfusion with CEUS, fused with MD-CT or MRI. RESULTS In 18/20 cases there was an accurate agreement with respect to the segmental localization of the tumor lesion. In 2/20 cases the localization was comparable with the image fusion of CEUS and reference imaging (a total of at least 65 lesions: 3 x 1 lesion, 5 x 2 lesions, 8 x 3 lesions, 2 x 5 lesions, 1 x 8 lesions, 1 x at least 10 lesions (multifocal)). With image fusion a certain characterization was attained in 17/20 cases. In 3/20 cases (lymphoma after liver transplantation, multifocal CCC, metastases of a neuroendocrine tumor) the diagnosis was at first doubtful and had to be confirmed histologically. In patients with HCC an evaluation of the tumor perfusion was feasible in all 9 cases (8/9 after local trans-arterial chemoembolization (TACE), 1/9 after radio frequency ablation (RFA)). A tendency toward the identification of more lesions with image fusion of CEUS and CT than with contrast-enhanced CT alone could be recognized (p=0.059). CONCLUSION Applying a new real-time fusion technique of MD-CT or MRI with CEUS new possibilities for the evaluation, intervention and monitoring of the therapy of liver lesions were made possible, since the method also comprised the dynamic microperfusion.

Quantitative assessment of bowel wall vascularisation in Crohn's disease with contrast-enhanced ultrasound and perfusion analysis

Patients with inflammatory bowel disease (IBD) often undergo several radiologic imaging studies, which - with the exception of magnetic resonance imaging (MRI) and B-scan ultrasound (US) - subject patients to ionizing radiation. With contrast enhanced ultrasound microvascular imaging of the bowel is possible. Hence, the aim of our study was to assess the perfusion pattern of inflamed bowel walls in Crohns disease compared with healthy volunteers quantitatively using a specific quantification software. We evaluated 4 volunteers and 20 patients with proven Crohns disease, who went through an active episode based on clinical symptoms and complementary imaging by MRI (19 patients) and computed tomography (1 patient), respectively, with dynamic contrast-enhanced ultrasound (CEUS) using a second generation contrast agent (SonoVue, Bracco, Germany). Retrospectively, we applied the quantification software Qontrast (Bracco, Italy) to obtain contrast-enhanced sonographic perfusion maps for each lesion. Patients had significant higher peak values (median 46.86, lower quartile 37.91, upper quartile 53.20) and significant higher regional blood volume (median 2133.65, lower quartile 1202.90, upper quartile 2820.44) than volunteers. Considering the very low peak value of the healthy, it is easy to understand that the time-to-peak was significantly shorter in the volunteers (median 4.45, lower quartile 1.82, upper quartile 6.88) than in the patients (median 12.15, lower quartile 9.18, upper quartile 15.74). Our study showed clear differences between inflamed and normal bowel wall vascularity regarding all perfusion parameters. These results show that a quantitative assessment of the bowel wall vascularisation and inflammation, respectively, is possible. The software used here enables us to collect data, not only in a semi-quantitative but also in a reproducible, quantitative manner which is comparable with the evaluation of CT or MRI generated data.

Magnetic resonance-guided percutaneous angioplasty of femoral and popliteal artery stenoses using real-time imaging and intra-arterial contrast-enhanced magnetic resonance angiography

Objective:The aim of this study was to demonstrate the possibility of performing magnetic resonance (MR)-guided interventional therapy for femoral and popliteal artery stenoses with commercially available materials supported by MR real-time imaging and intra-arterial MR angiography. Materials and Methods:A total of 15 patients suffering from symptomatic arterial occlusive disease of the lower limbs with 19stenoses were included. Interventional intra-arterial digital subtraction angiography was performed before and after angioplasty on each patient as standard of reference. MR images were acquired on a 1.5-T MR scanner. A fast-low-angle shot (FLASH) 3D sequence was applied for a contrast enhanced MR-angiography (ceMRA). A total of 5 mL of diluted gadodiamide was injected via the arterial access. Maximum intensity projections (MIPs) were used as roadmaps and localizers for the interactive positioning of a continuously running 2D-FLASH sequence with a temporal solution of 2 images/second. The lesion was crossed by a balloon-catheter, which was mounted on a guidewire. The visibility was provided by the radiopaque markers on the balloon and was improved by injection of 1 mL of gadolinium into the balloon. Postinterventional control was performed by intra-arterial MR angiography and catheter angiography. Results:Stenoses were localized by intra-arterial MR angiography. The guidewire/balloon combination was visible, and the balloon was placed correctly to cover the entire stenoses. Balloon dilation reduced the degree of stenosis by approximately 57% on average. No complications were observed. Conclusion:MR-guided balloon dilation of femoral and popliteal artery stenoses supported by real-time MR imaging and intra-arterial MR angiography is feasible with commercially available materials.

Image fusion with volume navigation of contrast enhanced ultrasound (CEUS) with computed tomography (CT) or magnetic resonance imaging (MRI) for post-interventional follow-up after transcatheter arterial chemoembolization (TACE) of hepatocellular carcinomas (HCC): Preliminary results

AIM The assessment of the immediate post-interventional microcirculation and perfusion following transcatheter arterial chemoembolization (TACE) with new real time imaging fusion technique (VNav) of computed tomography (CT) or magnetic resonance imaging (MRI) with contrast enhanced ultrasound (CEUS) compared to follow-up. MATERIAL Following TACE an image fusion of CEUS with CT or MRI of the liver was performed in 20 patients (18 men, 2 women; age 29-75 years) with confirmed hepatocelluar carcinoma (HCC) to evaluate the post-interventional tumor vascularization and perfusion of HCC tumor lesions. Image fusion with CEUS performed immediately was compared with the result at the end of TACE (DSA), with post TACE CT (non-enhanced CT within 24 hours) and with follow up CT (enhanced CT after 6 weeks) after embolization. Ultrasound was performed using a 1-5 MHz multifrequency SonoVue transducer (LOGIQ 9/GE) after a bolus injection of 2-4ml SonoVue® with contrast harmonic imaging (CHI). Thirteen examinations were fused with a contrast enhanced CT, 7 with a MRI performed before TACE. RESULTS The post-interventional volume navigation image fusion of CT or MRI with CEUS showed differences regarding the residual tumor perfusion compared to other modalities. The correlation (Spearman-test) between the perfusion result at the end of TACE, non-enhanced CT after TACE and image fusion with CEUS was 0.42 and 0.50. The difference between the result at the end of TACE and the fusion with CEUS was significant (p < 0.05, Wilcoxon-test). The correlation between fusion of CEUS with CT/MRI and follow-up CT (after 6 weeks) was 0.64, the difference was not significant (p > 0.05). The differences between native CT within 24 hours after TACE and follow up CT after 6 weeks or fusion of CEUS and CT/MRI were significant (p < 0.05). The inter-observer variability was 0.61 at the end of TACE, 0.58 at non-enhanced CT (within 24 hours), 0.87 at fusion CEUS with CT/MRI and 0.74 at follow up CT after 6 weeks (Cohens Kappa test). CONCLUSION Image fusion with volume navigation (VNav) of CEUS with CT or MRI allows an accurate localisation of foci in patients with HCC. This exact mapping permits an easier control and evaluation of the results after TACE. The fusion of CEUS and CT or MRI allows a better evaluation of the microcirculation and the residual tumor perfusion at an earlier point of time than usual modalities of therapy control like non-enhanced CT. This might lead to a more differentiated monitoring of therapy.

Amorphous silicon, flat-panel, x-ray detector versus storage phosphor-based computed radiography: contrast-detail phantom study at different tube voltages and detector entrance doses.

RATIONALE AND OBJECTIVES Evaluation of the contrast-detail performance of an active-matrix flat-panel x-ray detector in comparison with a storage phosphor system with special regard to the potential of dose reduction. METHODS A digital x-ray detector based on cesium iodide (CsI) and amorphous silicon (a-Si) technology was compared with a fifth-generation storage phosphor system. A lucite plate with 36 drilled holes of varying diameters and depths was used as contrast-detail phantom. At 45 kVp, 70 kVp, and 113 kVp, images at 8 different detector entrance doses ranging between 0.3 microGy and 40 microGy were obtained. On soft-copy displays, 3 masked observers evaluated the detectability of each aperture in each image according to a 5-point scale. The mean sum scores of corresponding images were compared. RESULTS For all tube voltages and detector entrance doses, the images obtained with the CsI/a-Si detector resulted in better observer contrast-detail performance as compared with the images of the storage phosphor system. The CsI/a-Si system allowed a calculated dose reduction of 39% at 45 kVp, 68% at 70 kVp, and 81% at 113 kVp as compared with the storage phosphor system, without loss of contrast-detail detectability. CONCLUSIONS Under the conditions of the chosen experimental design, the CsI/a-Si system provided a superior contrast-detail performance as compared with the storage phosphor system. The potential of dose reduction increased with rising tube voltage.Rationale and Objectives.To evaluate the quality of chest radiographs after 32:1 compression/decompression with different image compression algorithms. Methods.Ten digital (Thoravison) radiographs of an anthropomorphic chest phantom with superimposed simulated nodular lesions (NL) and linear reticular lesions (LL) were obtained. Each radiograph was subdivided into 15 fields; they contained the lesions with a probability of 0.5. The radiographs were compressed and decompressed by using JPEG, fractal and wavelet algorithms at a compression rate of 32:1. Five radiologists evaluated the images. Data were analyzed with the receiver operating characteristic (ROC) method (comparison of area under curve). Results.At 32:1 JPEG or wavelet compression, no statistically significant difference was observed for both NL and LL when compared with the original images. The fractal algorithm performed significantly lower for both NL and LL when compared with the original radiographs. Conclusion.The JPEG and wavelet image compression does not result in loss of relevant information for chest x-rays at a compression rate of 32:1.

Comparison of Conventional Abdominal CT with MR-Enterography in Patients with Active Crohn's Disease and Acute Abdominal Pain

RATIONALE AND OBJECTIVES Patients with known Crohns disease (CD) and an acute onset of severe abdominal pain attending an emergency room frequently undergo contrast-enhanced emergency computed tomography (CT) for complication assessment. To assess small bowel changes, an additional dedicated imaging procedure such as magnetic resonance enterography (MRE) is regularly performed. Therefore, these patients undergo two imaging procedures, although the clinical and diagnostic value of such an approach is not known. In a retrospective study, we compared the diagnostic value of a conventional abdominal CT with a dedicated small bowel MRE to assess bowel wall changes as well as typical complications in patients with advanced CD. MATERIALS AND METHODS We retrospectively evaluated 53 patients with CD having a conventional abdominal multidetector-CT (MD-CT) and MRE within 2 days. Image quality and bowel inflammation was analyzed for each bowel segment. Lymph nodes, abscesses, and fistulas were evaluated. RESULTS For small bowel and colon assessment, there was no significant difference for image quality between CT and MRE. Inflammation diagnosis was not significantly different between CT (69.4%) and MRE (71.4%). Colonic inflammation was diagnosed in 30.2% based on CT and 14.3% based on MRE. The difference for the detection of lymph nodes was significant (CT 49; MRE 27), whereas the differences between fistula (CT 25, MRE 27) or abscesses (CT and MRE 32) detection were not significant. CONCLUSIONS In patients with known advanced CD with acute abdominal pain conventional abdominal MD-CT, which is frequently performed as an emergency imaging procedure, is sufficient for bowel wall assessment. Based on our data, additional dedicated small bowel imaging such as MRE seems not to be necessary.

Peripheral Arterial Balloon Angioplasty: Effect of Short versus Long Balloon Inflation Times on the Morphologic Results

PURPOSE To evaluate the effect of different balloon inflation times on angiographic results in peripheral angioplasty. MATERIALS AND METHODS Seventy-four infrainguinal arteriosclerotic lesions were randomized prospectively to undergo balloon dilation for 30 seconds (group I) or 180 seconds (group II). Each group consisted of 37 patients. Postinterventional angiograms were evaluated by two blinded readers. Dissections were graded as follows: 1 = no dissection; 2 = minor flap; 3 = extensive dissection membrane, not flow limiting; or 4 = flow-limiting flap. The rate of major-grade dissections (grades 3 and 4), residual stenosis (>30%), and further interventions were compared with the two-tailed chi(2) test. RESULTS In group I, major dissections were noted in 16 patients (43%) compared with five patients (14%) in group II (P =.009). Residual stenoses were found in 12 patients (32%) in group I compared with five patients (14%) in group II (P =.096). The rate of additional interventions was significantly higher in group I than in group II (20 of 37 vs nine of 37; P =.017). CONCLUSION A prolonged inflation time of 180 seconds improves the immediate angioplasty result of infrainguinal lesions compared to a short dilation strategy. Significantly fewer major dissections and a modest reduction of residual stenoses are observed. The requirement of costly and time-consuming further interventions is significantly reduced.

Superselective arterial embolisation with a liquid polyvinyl alcohol copolymer in patients with acute gastrointestinal haemorrhage

ObjectivesTo evaluate the results of emergency embolisation in acute arterial bleeding of the gastrointestinal tract with a liquid polyvinyl alcohol copolymer from two centres.MethodsWe retrospectively analysed 16 cases (15 patients) of acute arterial bleeding of the gastrointestinal tract where emergency embolotherapy was performed by using the copolymer when acute haemorrhage was not treatable with endoscopic techniques alone. Cause of haemorrhage and technical and clinical success were documented.ResultsArterial embolotherapy was successful in all 16 cases. The technical success rate was 100%. The cause of bleeding was pancreatitis in four, graft-versus-host disease (GVHD) of the colon in three, malignancy in three, angiodysplasia in two, ulcer in two and panarteritis nodosa and trauma in one each. There were no procedure-related complications. No bowel necrosis occurred because of embolisation. In 13 cases, the patients were discharged in good condition (81%); the three patients with GVHD died because of the underlying disease.ConclusionsThe copolymer seems to have great potential in embolotherapy of acute arterial gastrointestinal bleeding. In our series none of the patients had rebleeding at the site of embolisation and no clinically obvious bowel necrosis occurred.

Radiologische Implantation zentralvenöser Portsysteme am Unterarm

PURPOSE To retrospectively analyze the technical result and long term outcome of central venous arm ports placed by radiologists. MATERIALS AND METHOD Over a 5-year period, 399 arm ports were implanted by radiologists in 391 patients. The system consists of a low profile titanium chamber and a silicone catheter. Ports were placed at the forearm after puncture of a vein proximally to the elbow under fluoroscopic guidance. In a retrospective analysis the technical results and the long term outcome were evaluated. Complications were documented according to the standards of the society of interventional radiology. RESULTS In 391 patients a total of 98 633 catheter days were documented (1 - 1325 days, mean 252 days). Primary technical success was 99.25 % (396 / 399) with a 100 % secondary technical success rate. No severe procedural complications, e. g. pneumothorax or severe hemorrhage, were found. A total of 45 complications occurred (11.28 %, 0.45 / 1000 catheter days), including 8 portal pocket infections (27 - 205 days, mean 115 days). Fifteen ports were explanted because of complications. The complication rate corresponds to the data from subclavian ports and is less than the complication rates published in large surgical trials. CONCLUSION Implantation of central-venous arm ports by radiologists is safe and minimally invasive. No severe immediate procedural complications occur due to the peripheral implantation site. Long term complication rates are comparable to other studies of radiological or surgical port implantation at different sites.

BLADE in Sagittal T2-Weighted MR Imaging of the Cervical Spine

BACKGROUND AND PURPOSE: Image quality and diagnostic reliability of T2-weighted MR images of the cervical spine are often impaired by several kinds of artifacts, even in cooperative patients. The aim of this study was to evaluate if BLADE sequences might solve these problems in a routine patient collective. MATERIALS AND METHODS: TSE and BLADE sequences were compared in 60 patients for T2-weighted sagittal imaging of the cervical spine. Image sharpness, motion artifacts, truncation artifacts, metal artifacts, CSF flow phenomena, contrast of anatomic structures (vertebral body/disk, spinal cord/CSF), and diagnostic reliability of spinal cord depiction were evaluated by 2 independent readers. Another 2 readers selected the sequence they would prefer for diagnostic purposes. Statistical evaluations were performed by using the Wilcoxon and the χ2 test; differences with P < .05 were regarded as statistically significant. RESULTS: BLADE was significantly superior to TSE regarding image sharpness, image contrast, diagnostic reliability of spinal cord depiction, motion artifacts, CSF flow phenomena, and truncation artifacts; for metal artifacts no significant improvements were found. In 50 of 60 patients, BLADE was preferred for diagnostic purposes, and TSE was favored in 3 patients. The number of examinations that were nondiagnostic due to impaired spinal cord depiction was reduced from 12 in TSE to 3 in BLADE, and nondiagnostic examinations due to overall motion artifacts were reduced from 2 to 1. CONCLUSIONS: Using the BLADE sequence for sagittal T2-weighted imaging of the cervical spine proved to be advantageous to reduce various kinds of artifacts.