Radiation exposure during TACE procedures using additional cone-beam CT (CBCT) for guidance: safety and precautions.

Background During transarterial chemoembolization (TACE), cone-beam computed tomography (CBCT) can be used for tumor and feeding vessel detection as well as postembolization CT imaging. However, there will be additional radiation exposure from CBCT. Purpose To evaluate the additional dose raised through CBCT-assisted guidance in comparison to TACE procedures guided with pulsed digital subtraction angiography (DSA) alone. Material and Methods In 70 of 140 consecutive patients undergoing TACE for liver cancer, CBCT was used to facilitate the TACE. Cumulative dose area product (DAP), cumulative kerma(air), DAP values of DSA, total and cine specific fluoroscopy times (FT) of 1375 DSA runs, and DAP of 91 CBCTs were recorded and analyzed using Spearman's correlation, Mann-Whitney U-test, and Kruskal-Wallis test. P values < 0.05 were considered significant. Results Additional CBCT increased DAP by 2% ( P = 0.737), kerma(air) by 24.6% ( P = 0.206), and FT by 0.02% ( P = 0.453). Subgroup analysis revealed that postembolization CBCT for detection of ethiodized oil deposits added more DAP to the procedure. Performing CBCT-assisted TACE, DSA until first CBCT contributed about 38% to the total DAP. Guidance CBCT acquisitions conduced to 6% of the procedure's DAP. Additional DSA for guidance after CBCT acquisition required approximately 46% of the mean DAP. The last DSA run for documentation purposes contributed about 10% of the DAP. Conclusion CBCT adds radiation exposure in TACE. However, the capability of CBCT to detect vessels and overlay in real-time during fluoroscopy facilitates TACE with resultant reduction of DAPs up to 46%.

Detection and characterisation of focal liver lesions in colorectal carcinoma patients: comparison of diffusion-weighted and Gd-EOB-DTPA enhanced MR imaging.

OBJECTIVE: To compare diffusion-weighted imaging (DWI) and Gd-EOB-DTPA-enhanced magnetic resonance (MR) imaging for the detection and characterisation of focal liver lesions (FLLs) in patients with colorectal carcinoma. METHODS: Seventy-three patients underwent MR imaging including echoplanar DWI (MR-DWI) and dynamic (MR-Dyn) and hepatobiliary phase (MR-Late) Gd-EOB-DTPA-enhanced images. Two blinded readers independently reviewed 5 different image sets using a 5-point confidence scale. Accuracy was assessed by the area (A(z)) under the receiver operating characteristic curve, and sensitivity and specificity were calculated. RESULTS: A total of 332 FLLs were evaluated. Detection rates were significantly higher for MR-Late images (94.4% for benign and 100% for malignant lesions) compared with MR-DWI (78.3% and 97.5%) and MR-Dyn images (81.5% and 89.9%). Accuracy was 0.82, 0.76 and 0.89 for MR-DWI, MR-Dyn and MR-Late images while sensitivity was 0.98, 0.87 and 0.95, respectively. For characterisation of subcentimetre lesions sensitivity was highest for MR-DWI (0.92). Combined reading of unenhanced and contrast-enhanced images had an identical high accuracy of 0.98. CONCLUSION: Late-phase Gd-EOB-DTPA-enhanced images were superior for the detection of FLLs, while DWIs were most valuable for the identification of particularly small metastases. Combined interpretation of unenhanced images resulted in precise characterisation of FLLs.

No bone tunnel enlargement in patients with open growth plates after transphyseal ACL reconstruction.

Bone tunnel enlargement after ACL reconstruction has been described extensively in adults. However, little is known about this phenomenon in patients with open growth plates. Thus, the goals of the current study were to evaluate changes in bone tunnel size in patients with open growth plates after transphyseal ACL reconstruction with suspensory fixation and to correlate tunnel size with clinical outcome after medium-term follow-up. Fourteen patients with open growth plates were included that underwent primary transphyseal ACL reconstruction using hamstrings autografts and suspensory fixation. Mean follow-up time was 7 years. At the time of follow-up, MRIs of the operated knee were performed, and outcome was assessed using KOS-ADLS, Lysholm score, IKDC Subjective Knee Form score, Knee Examination Form score, and KT-1000 measurements. On MRI, the cross-sectional area of the bone tunnels was assessed using special axial cuts perpendicular to the axes of the tunnels. Two orthopaedic surgeons and two radiologists analysed the MRIs. Change in bone tunnel size from surgery to follow-up was calculated. No significant changes in bone tunnel size from surgery to follow-up were found. Regarding outcome measures, KOS-ADLS averaged 95%, Lysholm Score averaged 96 points, IKDC Subjective Knee Form averaged 95%, IKDC Knee Examination Form scores were 8A, 5B, 1C, and KT-1000 measurements averaged 1.8 ± 1.4 mm. No significant correlations were found between tunnel size at follow-up and outcome measures. Based on our study, bone tunnel enlargement does not occur in patients who have open growth plates and undergo ACL reconstruction using suspensory fixation.

[Diagnostic value of multislice perfusion CT in dementia patients]. / Bedeutung der zerebralen Perfusionsmessung am Mehrzeilenspiral-CT in der Demenzdiagnostik.

BACKGROUND: The diagnostic value of perfusion CT in dementia patients was retrospectively evaluated in comparison to the Mini-Mental State Examination (MMSE). MATERIAL AND METHODS: The perfusion CT database of 55 subjects was investigated. All patients underwent an unenhanced, contrast-enhanced, and perfusion CT of the head. The clinical evaluation of the degree of dementia was performed with the MMSE. In the perfusion CT data, 24 ROI were marked. Then blood volume (BV), blood flow (BF), and mean transit time (MTT) were calculated and compared with the ipsilateral and contralateral regions and with the degree of dementia. RESULTS: With increasing degree of dementia, a significant decrease of the occipital and temporal BV was found. A significant decrease of the BF in the frontal lobe, basal ganglia, and occipital region was found. Concurrently, the MTT increased significantly in the basal ganglia region. The group with Alzheimer's disease showed significant regional hypoperfusion compared with the group of cognitively normal subjects in the frontal, basal ganglia, occipital, and temporal region. CONCLUSIONS: The cerebral perfusion decreased with increasing degree of dementia. The inexpensive and widely available perfusion CT reveals information about regional differences of cerebral perfusion, which may be useful in differentiating severity and types of dementia.

MR-guided interstitial laser thermotherapy of colorectal liver metastases: efficiency, safety and patient survival.

PURPOSE: Evaluation of MR-guided interstitial laser thermotherapy (ILT) of colorectal liver metastases under consideration of efficacy, safety and patient survival. MATERIALS AND METHODS: Sixty-six inoperable patients with a total of 117 colorectal liver metastases were treated with MR-guided laser therapy in 96 sessions. 40.9% of patients presented metastases from rectum carcinoma, 30.3% from sigmoid carcinoma and 28.8% from colon carcinoma. Inclusion criteria were < or =5 metastases < or =5 cm in greatest diameter and no extrahepatic tumor spread. Internally water-cooled 9F power-laser-applicators were placed under CT-fluoroscopy. For MR-guided ILT, a 1064 nm Nd-YAG-lasers with a beam divider with multi applicator technique was used. The energy applied was 10 watt per centimeter diffusor length, with the diffusor length ranging from 20 to 40 mm. The mean duration of the energy application was 23 minutes (range: 15 - 37 minutes). The endpoint of the laser ablation was defined as the absence of hyperintense tumor tissue in the continuously monitored T2-w fat saturated gradient-echo sequences. Follow-up included contrast-enhanced MRI using T1- and T2-weighted spin-echo and gradient-echo sequences every three months after treatment. Survival times were calculated using the Kaplan-Meier method. RESULTS: The median follow-up was 8.7 months (mean 11.8; standard deviation 9.9; range 1 to 36). The overall median progression free survival was 6.1 months (range, 0.3 to 27+ months). Median survival was 23 months (95% CI, 17-29 months). The rate of major complications was 2.1% (n = 2) and peri-procedural mortality (30 days) was 3% (n = 2). After 3, 6, 9, and 12 months, local tumor control was 98.3%, 91.4%, 76.1%, and 69.4%, respectively. In no patient metastatic deposits along the catheter access route were found. CONCLUSIONS: In patients with colorectal liver metastases, interstitial laser thermotherapy is an effective and safe therapeutic option and therefore suitable not only in palliative situations.

Activity-based cost analysis of hepatic tumor ablation using CT-guided high-dose rate brachytherapy or CT-guided radiofrequency ablation in hepatocellular carcinoma.

PURPOSE: To analyse and compare the costs of hepatic tumor ablation with computed tomography (CT)-guided high-dose rate brachytherapy (CT-HDRBT) and CT-guided radiofrequency ablation (CT-RFA) as two alternative minimally invasive treatment options of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: An activity based process model was created determining working steps and required staff of CT-RFA and CT-HDRBT. Prorated costs of equipment use (purchase, depreciation, and maintenance), costs of staff, and expenditure for disposables were identified in a sample of 20 patients (10 treated by CT-RFA and 10 by CT-HDRBT) and compared. A sensitivity and break even analysis was performed to analyse the dependence of costs on the number of patients treated annually with both methods. RESULTS: Costs of CT-RFA were nearly stable with mean overall costs of approximately 1909 €, 1847 €, 1816 € and 1801 € per patient when treating 25, 50, 100 or 200 patients annually, as the main factor influencing the costs of this procedure was the single-use RFA probe. Mean costs of CT-HDRBT decreased significantly per patient ablation with a rising number of patients treated annually, with prorated costs of 3442 €, 1962 €, 1222 € and 852 € when treating 25, 50, 100 or 200 patients, due to low costs of single-use disposables compared to high annual fix-costs which proportionally decreased per patient with a higher number of patients treated annually. A break-even between both methods was reached when treating at least 55 patients annually. CONCLUSION: Although CT-HDRBT is a more complex procedure with more staff involved, it can be performed at lower costs per patient from the perspective of the medical provider when treating more than 55 patients compared to CT-RFA, mainly due to lower costs for disposables and a decreasing percentage of fixed costs with an increasing number of treatments.

[Comparison of radiation dose and image quality of Siremobil-IsoC(3D) with a 16-slice spiral CT for diagnosis and intervention in the human pelvic bone]. / Vergleich von Strahlenexposition und Bildqualität eines Siremobil-IsoC(3D) mit einem 16-Zeilen-Spiral-CT bei Diagnostik und Intervention am humanen Becken.

PURPOSE: To compare the image quality of 16-slice computed tomography with the image quality of Siremobil-IsoC (3D) of the pelvic region and to measure simultaneously the radiation dose before and after implantation of a sacroiliac screw (SI-screw) MATERIALS AND METHODS: The pelvic region of 8 human cadavers was examined in the Siremobil-IsoC (3D) at five different levels. We used a standard protocol for the 16-slice CT of the complete pelvic region before and after insertion of a pelvic screw, followed by stepwise reduction of the tube current to find the tube current that equalizes the image quality of both modalities. We controlled the image quality by judging important structures such as neuroforamen, nerves, sacroiliacal joint space, intervertebral space, osteophytes, iliopsoas muscle, acetabular surface, fovea centralis, hip joint and os pubis. The image quality was judged by three radiologists and three trauma surgeons using a ranking from 1 to 5. The dose was measured with an endorectally placed NOMEX Dosimeter, to obtain the gonadal dose. RESULTS: The medium score for all viewers of the Siremobil-IsoC (3D) examinations was between 3 and 4.3. The medium score for all CT-examinations with a tube current of 250 mA was between 1.3 and 2.2. The reduction of tube current down to 80 mA hardly influenced the marks for the analyzed structures. Under 80 mA, bony structures, even after implantation of a SI-screw, were still marked as good, but soft tissue differentiation was getting worse. For the examination of the pelvis, the average dose-length product for the IsoC (3D) was 41.2 mGy x cm. The medium dose-length product for CT was 389 mGy x cm for 250 mA, 125 mGy x cm for 80 mA and 82 mGy x cm for 60 mA. CONCLUSION: The Siremobil-IsoC (3D) is sufficient for therapeutic intraoperative purpose, but the image quality is not sufficient for diagnostic purpose. The higher dose-length product of a CT examination is justifiable because of a better overview, shorter examination time and qualitative superiority. An advantage of the Siremobil-IsoC (3D) is the intraoperative availability with acceptable 3D image quality compared to conventional fluoroscopy.

[Comparison of different MRI sequences with and without application of Gd-BOPTA as follow-up after LITT]. / Vergleich unterschiedlicher MRT-Sequenzen mit und ohne Applikation von Gd-BOPTA zur Verlaufskontrolle nach LITT.

PURPOSE: Comparison of various MR imaging techniques without and with the application of Gd-BOPTA for the follow-up of thermal tumor ablations by means of laser-induced therapy (LITT). MATERIALS AND METHODS: Thermal tumor ablations were performed with LITT in 19 patients showing a local recurrence. The metastases were from colorectal carcinoma in 15 cases (78.9 %) and from cervix, bronchial, gastric and renal carcinoma respectively in one patient each. The size of the metastases before ablation was on average 38.5 mm (min = 25 mm, max = 58 mm). The MRI protocol consisted of T2 UTSE FS, T1 w GRE without and with Gd-BOPTA at an early (20 s post injection) and late stage (> 120 min post injection). Two independent radiologists evaluated image contrast of the local relapse and necrosis in comparison to the surrounding healthy liver parenchyma on a scale from - 10 to + 10. Liver parenchyma was in any sequence 0. Recurrences were confirmed with follow-up examinations in all patients. Statistical analysis was performed by means of Wilcoxon and Kendall's W-test. RESULTS: Both radiologists found absolute ratios for contrast differences between thermal necrosis and local recurrence, with an average of 10.95 for T2 w UTSE FS and of 6.58 for T1 w GRE without, and of 4.05 for T1 w GRE with Gd-BOPTA in the early and of 2.26 in the late stage. Superiority for UTSE FS was significant (p < 0.05). The statistical analysis showed a high agreement for both radiologists for all values (p < 0.001). CONCLUSION: For early detection of local recurrences after thermal ablation T2 w UTSE FS is most suitable. For the detection of new foci, the use of liver specific contrast media is advisable.

[The diagnostic value of radial multiplanar reformatting (MPR) in the CT-diagnosis of pulmonary embolism]. / Stellenwert radiärer Reformatierungen in der CT-Diagnostik der Lungenarterienembolie.

PURPOSE: To evaluate the diagnostic value of radial reformatting of axial multislice CT (MS-CT) data sets in the presumptive diagnosis of pulmonary embolism. MATERIALS AND METHODS: In 126 cases with the presumptive diagnosis of an acute pulmonary embolism, 4- and 8-slice axial MS-CT data sets were radially reformatted. The pulmonary vessels were evaluated by five experienced radiologists who determined the number of thrombi at the level of the segmental and subsegmental arteries. A pulmonary artery was considered as thrombosed if it showed at least one unambiguous filling defect on two consecutive sections. It was determined whether the artery was uniformly opacified without filling defects, contained thrombotic material or was completely occluded by a blood clot. Pulmonary vessels that could not be evaluated because of moving artifacts or inadequate opacification were classified as negative. Finally, all experts gave a subjective estimate concerning the simplicity of the diagnosis for both reconstructions. RESULTS: The diagnosis of thromboembolism at a subsegmental level was significantly different for axial sections and radial reconstruction: at 4-slice CT, 77 subsegmental thromboembolisms were found in axial sections vs. 98.6 in radial reconstructions; at 8-slice CT, 23.6 in axial sections vs. 31.2 in radial reconstructions; and using the combined evaluation, 103.2 in axial sections vs. 130.6 in radial reconstructions, with a significance of p = 0.043. The five judges did not find any significant differences in the number of the blood clots in each pulmonary segment. Concerning the simplicity of the diagnosis, the subjective judgment classified the radial reconstructions as better in 49.7 % and the axial sections as better in 22 %. The radial reconstructions of the 4-slice CT were classified as better in 45.7 % vs. 25 % and the 8-slice CT as better in 66 % vs. 16 %. CONCLUSION: Using radial multiplanar reformatting of the MS-CT data sets improves significantly the recognition of subsegmental pulmonary embolism.

Percutaneous computer tomography-guided ethanol sympathicolysis for the treatment of resistant arterial hypertension.

PURPOSE: As an alternative to catheter-based radiofrequency (RF) ablation, renal sympathicolysis can also be achieved by image-guided percutaneous injection of ethanol around the renal artery. MATERIALS AND METHODS: We report the case of a 50-year-old man with refractory hypertension and end-stage renal failure of unclear etiology who was treated with computed tomography-guided percutaneous periarterial ethanol sympathicolysis. RESULTS: The procedure was painless. The patient's BP decreased within 6 days from a baseline value of 172/84 mm Hg (1 week before treatment) to a sustained decreased value of 143/70 mm Hg 1 month after intervention, i.e., a decrease by 29/14 mm Hg. The patient's hypertension-related headache resolved. CONCLUSION: Image-guided periarterial ethanol injection for renal sympathetic denervation in a patient with drug-resistant hypertension is feasible. We provide a detailed description of this new interventional procedure and discuss its potential advantages compared with catheter-based RF ablation.

Prospective Evaluation of the radiologist's hand dose in CT-guided interventions.

PURPOSE: Assessment of radiologist's hand dose in CT-guided interventions and determination of influencing factors. MATERIALS AND METHODS: The following CT-guided interventions were included: Core biopsy, drainage, periradicular therapy, and celiac plexus neurolysis. The hand dose was measured with an immediately readable dosimeter, the EDD-30 (Unfors, Sweden). The default parameters for CT fluoroscopy were 120 kV, 90 mA and a 4 mm slice thickness. All interventions were performed on a 16-slice CT unit (Aquilion 16 Toshiba, Japan). The tumor size, degree of difficulty (1 - 3), level of experience and device parameters (mAs, dose-length product, scan time) were documented. RESULTS: 138 CT-guided interventions (biopsy n = 99, drainage n = 23, pain therapy n = 16) at different locations (lung n = 41, retroperitoneum n = 53, liver n = 25, spine n = 19) were included. The lesion size was 4 - 240 mm (median: 23 mm). The fluoroscopy time per intervention was 4.6 - 140.2 s (median: 24.2 s). The measured hand dose ranged from 0.001 - 3.02 mSv (median: 0.22 mSv). The median hand dose for lung puncture (n = 41) was slightly higher (median: 0.32 mSv, p = 0.01) compared to that for the liver, retroperitoneum and other. Besides physical influencing factors, the degree of difficulty (p = 0.001) and summed puncture depth (p = 0.004) correlated significantly with the hand dose. CONCLUSION: The median hand dose for different CT-guided interventions was 0.22 mSv. Therefore, the annual hand dose limit would normally only be reached with about 2000 interventions.

Treatment of osteoid osteoma using CT-guided radiofrequency ablation versus MR-guided laser ablation: a cost comparison.

OBJECTIVE: To compare the costs of CT-guided radiofrequency ablation (RFA) and MR-guided laser ablation (LA) for minimally invasive percutaneous treatment of osteoid osteoma. MATERIALS AND METHODS: Between November 2005 and October 2011, 20 patients (14 males, 6 females, mean age 20.3±9.1 years) underwent CT-guided RFA and 24 patients (18 males, 6 females; mean age, 23.8±13.8 years) MR-guided LA (open 1.0 Tesla, Panorama HFO, Philips, Best, Netherlands) for osteoid osteoma diagnosed on the basis of clinical presentation and imaging findings. Prorated costs of equipment use (purchase, depreciation, and maintenance), staff costs, and expenditure for disposables were identified for CT-guided RFA and MR-guided LA procedures. RESULTS: The average total costs per patient were EUR 1762 for CT-guided RFA and EUR 1417 for MR-guided LA. These were (RFA/LA) EUR 92/260 for equipment use, EUR 149/208 for staff, and EUR 870/300 for disposables. CONCLUSION: MR-guided LA is less expensive than CT-guided RFA for minimally invasive percutaneous ablation of osteoid osteoma. The higher costs of RFA are primarily due to the higher price of the disposable RFA probes.

MRI versus bone scintigraphy. Evaluation for diagnosis and grading of stress injuries.

AIM: This study was set up to determine the value of magnetic resonance imaging (MRI) and bone scintigraphy (BS) for the diagnosis of stress injuries in athletes, and furthermore to assess reliability and prediction of healing time. PATIENTS, METHODS: Imaging data was analyzed retrospectively from 28 athletes who had received MRI and BS examinations for suspected stress injuries. MRI- and BS-data were rated by three specialists each in a blinded read, using a 5-point score (i.e. 0-4: inconspicuous to high-grade stress fracture). An interdisciplinary expert truth-panel set the reference standard. Standard statistical parameters, Fleiss' kappa (κ), and group comparisons were calculated. RESULTS: The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) for detection of stress injuries were 71.4%, 85.7%, 78.6%, 83.3% and, 75.0%, for MRI and 92.9%, 73.8%, 83.3%, 78.0% and, 91.2% for BS, respectively. Interobserver reliability for the diagnosis of a stress injury was κ = 0.9 for BS and κ = 0.85 for MRI. Mean healing times of mild (grades 1 and 2) and severe (grades 3 and 4) stress injuries were 88 days (d) versus 142d for BS and 57d versus 116d for MRI. No significant difference in healing time could be shown. CONCLUSIONS: MRI and BS reliably detect stress injuries. MRI is to be recommended as the primary imaging modality due to its potential for assessment of differential diagnoses and the lack of radiation exposure, the value of BS lies in the exclusion of stress fractures after inconclusive MRI examinations.

Radiographic techniques for the localization and treatment of gastrointestinal bleeding of obscure origin.

PURPOSE/BACKGROUND: Acute gastrointestinal bleeding (GIB) is an emergency with high mortality rates, which requires a quick localization and treatment of the bleeding site. In this article, we give a summary of the diagnostic and interventional treatment of acute GIB with an emphasis on radiological methods. METHODS: The MEDLINE database identified relevant studies up until January 2011. Furthermore, experiences drawn from a highly experienced department of diagnostic radiology (~60 transarterial embolizations [TAEs]/year) were taken into account. RESULTS: Clinical risk scores are useful tools to triage patients for appropriate treatment. High-risk patients should undergo emergency endoscopy within 24 h. If endoscopical control of the bleeding cannot be achieved, a computed tomography angiography (CTA) should be done. If active bleeding (or if an active bleeding site) is found, in most cases, TAE should be performed prior to surgery because of the equal mortality rates with lower complication rates. If the site of bleeding is not identified and the patient is stable, a "watch-and-wait" strategy can be pursued. Especially for intermittent bleeding, scintigraphy with tagged red blood cells can be useful. CONCLUSION: Managing obscure acute GIB remains a challenge. The best patient care is achieved with a multidisciplinary team of endoscopists, experienced surgeons, and interventional radiologists. If emergency endoscopy fails, a CTA has to be done, which is more sensitive than conventional angiography. Based on CTA findings, a decision must be made between TAE and surgical intervention.

Computed tomographic criteria for the discrimination of subcentimeter lung nodules in patients with soft-tissue sarcomas.

The aim of this study was to identify criteria for nodule characterization on chest computed tomography in patients with soft tissue sarcomas. In 195 patients, a total of 194 benign and 117 malignant subcentimeter lung nodules were retrospectively analyzed according to lesion size, shape, margins, density, and localization. Benign lesions more frequently displayed complex shape and were of ground-glass density (P<.0001, respectively). In contrast, round shape and solid density were more frequently found in malignant lesions (P<.0001, respectively).

[First experiences with intravenous port systems authorized for high pressure injection of contrast agent in multiphasic computed tomography]. / Erste Erfahrungen mit intravenösen Portsystemen mit der Zulassung zur Hochdruckinjektion von Kontrastmittel in der Computertomografie.

PURPOSE: The aim of this prospective study was to examine two port systems for intravenous chemotherapy, authorized for high pressure injection, with respect to implantation, complications, implementation, and patency. MATERIALS AND METHODS: 40 high pressure port systems of the two available models (20 x Power Port [Bard], 20 x T-Port-Contrast [PFM]) and 20 standard port systems (X-Port [BARD]) as the control group were implanted. Both high pressure systems are authorized for injection with a maximum pressure of 300 PSI. The patient population was comprised of patients with different malignomas and liver metastases. At regular intervals following the protocol of the chemotherapy, multiphasic CT for tumor staging was carried out. RESULTS: The intravenous port systems were implanted without complications under sonographic guidance with transjugular access. The mean implantation time was 30 min (range: 22 - 40 min). After a median follow-up time of 6 months, the port patency was 100%. No port infections and no complications during high pressure injection of contrast agent occurred during this period. The level of contrast measured in the aorta was equivalent to the level of contrast in the vessels when contrast agent is administered over a large peripheral intravenous access. CONCLUSION: The intravenous high pressure port systems are equivalent to standard systems with regard to implantation and implementation. Intravenous chemotherapy can be performed as usual. The advantage is the possibility of multiphasic CT with authorized flow rates of up to 5 ml/sec.

Indirect MR-arthrography in osteochondral autograft and crushed bone graft with a collagen membrane--correlation with histology.

OBJECTIVE: To analyze the spectrum of findings in indirect MR-arthrography following osteochondral autograft transfer system (OATS) and crushed bone graft using a magnetic resonance imaging (MRI) scoring and grading system in relation to histology as the standard of reference. MATERIALS AND METHODS: Iatrogenic lesions were set at ovine condylar facets (n=6/group), treated with OATS or crushed bone graft. 1.5 T MRI was performed 6 months after surgery using PD-weighted (w fat saturated (fs) fast spin echo (FSE), T1-w 2D, and 3D fs gradient echo (GE) sequences 30 min. after i.v. Gd-DTPA administration and passive joint exercise. The repair tissue was evaluated by two independent radiologists. The MR findings were compared to histology. RESULTS: In all cases, MRI and histologic grading correlated well and showed significant superior repair in OATS at 6 months (p<0.05), reproducing the original articular contour and a good subchondral restoration. FsT1-w3DGE proved most appropriate identifying characteristic post-operative findings: the OATS group demonstrated bone marrow edema at the donor site and the graft/host interface showed significant enhancement in indirect MR-arthrography, indicating fibrocartilage. After crushed bone graft, we found an irregular structure and significant contrast uptake, consistent with remnants of bone grafts surrounded by inflammatory tissue. CONCLUSION: Indirect MR-arthrography is an accurate, non-invasive monitoring tool following OATS and crushed bone graft as the MRI scoring and grading system allows a reliable evaluation of normal and pathological osteochondral repair with a high histologic correlation.

[Photoelastic stress analysis of human femurs before and after implantation of different models of femur neck prostheses]. / Spannungsoptische Oberflächenanalyse an humanen Femurpräparaten vor und nach Implantation unterschiedlicher Schenkelhalsprothesenmodelle.

AIM: The aim of this study was the detection of areas at risk at the proximal femur after implantation of different femur neck prostheses using the photoelastic stress analysis. METHODS: Twelve pairs of human femurs were used as examination material. The analysis of the stress pattern was done with a stepwise increasing load up to the quadruple of body weight before and after implantation of three models of femur neck prostheses which were implanted cementless. The "CUT" and "Cigar" models are coated with a tripod structure. The "Cigar" model has a lateral thrust plate. The lateral end of the "CUT" model is curved and this end is attached to the lateral corticalis. The third model, the "rip prosthesis" has two layers for rotational stability. Subsequently, the micromotions of the implanted prosthesis in the femural neck were examined with alternating weight loads (1000 +/- 700 N). RESULTS: The Cigar prosthesis showed the most changes of stress distribution because of the lateral thrust plate with concentration of isochromatic lines to the lateral boring. In the region of the oseotomy an increase of strain up 1440 microm/m could be detected for the Cigar and up to 1000 microm/m for the rib prosthesis. The stress pattern after implantation of the CUT prosthesis remained very similar apart from a slight increase of stress values (720 microm/m). Only for the Cigar prostheses were the measured micromotions below the critical value for a possible osteointegration with a mean value of 134 microm/m. CONCLUSION: The stress pattern after implantation of the CUT prosthesis remained most similar to the preinterventional stress distribution. Because of this, it is to be expected that the osseous modification would stay at a low level. The question of osteointegration can only be answered in long-term in-vivo studies.

Thermoablation of liver metastases: efficacy of temporary celiac plexus block.

PURPOSE: To determine the efficacy of celiac plexus block during thermoablation of liver metastases. METHODS: Fifty-five consecutive patients underwent thermoablation therapy of liver tumors by laser-induced thermotherapy. Twenty-nine patients received a temporary celiac plexus block, 26 patients acted as control group. In both groups fentanyl and midazolam were administered intravenously upon request of the patient. The duration of the intervention, consumption of opiates, and individual pain sensations were documented. RESULTS: No complications resulting from the celiac plexus block were recorded. Celiac plexus block significantly reduced the amount of pain medication used during thermoablation therapy of liver tumors (with block, 2.45 mug fentanyl per kg body weight; without block, 3.58 mug fentanyl per kg body weight, p < 0.05; midazolam consumption was not reduced) in patients with metastases < or = 5 mm from the liver capsule. For metastases farther away from the capsule no significant differences in opiate consumption were seen. Celiac plexus block reduced the time for thermoablation significantly (178 min versus 147 min, p < 0.05) no matter how far the metastases were from the liver capsule. Average time needed to set the block was 12 min (range 9-15 min); additional costs for the block were marginal. As expected (as pain medications were given according to individual patients' needs) pain indices did not differ significantly between the two groups. CONCLUSION: In patients with liver metastases < or = 5 mm from the liver capsule, celiac plexus block reduces the amount of opiates necessary, simplifying patient monitoring. In addition celiac plexus block reduces intervention time, with positive effects on overall workflow for all patients.