A Uremic Pig Model for Peritoneal Dialysis.

With increasing interest in home dialysis, there is a need for a translational uremic large animal model to evaluate technical innovations in peritoneal dialysis (PD). To this end, we developed a porcine model with kidney failure. Stable chronic kidney injury was induced by bilateral subtotal renal artery embolization. Before applying PD, temporary aggravation of uremia was induced by administration of gentamicin (10 mg/kg i.v. twice daily for 7 days), to obtain uremic solute levels within the range of those of dialysis patients. Peritoneal transport was assessed using a standard peritoneal permeability assessment (SPA). After embolization, urea and creatinine concentrations transiently increased from 1.6 ± 0.3 to 7.5 ± 1.2 mM and from 103 ± 14 to 338 ± 67 µM, respectively, followed by stabilization within 1-2 weeks to 2.5 ± 1.1 mM and 174 ± 28 µM, respectively. Gentamicin induced temporary acute-on-chronic kidney injury with peak urea and creatinine concentrations of 16.7 ± 5.3 mM and 932 ± 470 µM respectively. PD was successfully applied, although frequently complicated by peritonitis. SPA showed a low transport status (D/P creatinine at 4 h of 0.41 (0.36-0.53)) with a mass transfer area coefficient of 9.6 ± 3.1, 4.6 ± 2.6, 3.4 ± 2.3 mL/min for urea, creatinine, and phosphate respectively. In conclusion, this porcine model with on-demand aggravation of uremia is suitable for PD albeit with peritoneal transport characterized by a low transport status.

Arterio-ureteral fistula: a nationwide cross-sectional questionnaire analysis.

PURPOSE: Arterio-ureteral fistula (AUF) is an uncommon diagnosis, but potentially lethal. Although the number of reports has increased over the past two decades, the true incidence and contemporary urologists' experience and approach in clinical practice remains unknown. This research is conducted to provide insight in the incidence of AUF in The Netherlands, and the applied diagnostic tests and therapeutic approaches in modern practice. METHODS: A nationwide cross-sectional questionnaire analysis was performed by sending a survey to all registered Dutch urologists. Data collection included information on experience with patients with AUF; and their medical history, diagnostics, treatment, and follow-up, and were captured in a standardized template by two independent reviewers. Descriptive statistics were used. RESULTS: Response rate was 62% and 56 AUFs in 53 patients were reported between 2003 and 2018. The estimated incidence of AUF in The Netherlands in this time period is 3.5 AUFs per year. Hematuria was observed in all patients; 9% intermittent microhematuria, and 91% presenting with, or building up to massive hematuria. For the final diagnosis, angiography was the most efficient modality, confirming diagnosis in 58%. Treatment comprised predominantly endovascular intervention. CONCLUSION: The diagnosis AUF should be considered in patients with persistent intermittent or massive hematuria.

Arterio-Ureteral Fistula: Systematic Review of 445 Patients.

PURPOSE: Arterio-ureteral fistula (AUF) is an uncommon diagnosis, but increasingly reported and potentially lethal. This systematic review comprehensively presents risk factors, pathophysiology, location and clinical presentation of AUF aiming to increase clinical awareness of this rare but life-threatening condition, and to put this entity into a contemporary perspective with modern diagnostic tools and treatment strategies. MATERIALS AND METHODS: This review was performed according to the PRISMA (Preferred Reporting Items for a Systematic Review and Meta-Analysis of Individual Participant Data) guidelines. A literature search in PubMed® and EMBASE™ was conducted. In addition, retrieved articles were cross-referenced. Data parameters included oncologic, vascular and urological history, diagnostics, treatment, and followup, and were collected using a standard template by 2 independent reviewers. RESULTS: A total of 245 articles with 445 patients and 470 AUFs were included. Most patients had chronic indwelling ureteral stents (80%) and history of pelvic oncology (70%). Hematuria was observed in 99% of the patients, of whom 76% presented with massive hematuria with or without previous episodes of (micro)hematuria. For diagnosis, angiography had a sensitivity of 62%. The most predominant location of AUF was at the common iliac artery ureteral crossing. AUF-specific mortality before 2000 vs after 2000 is 19% vs 7%, coinciding with increasing use of endovascular stents. CONCLUSIONS: AUF should be considered in patients with a medical history of vascular surgery, pelvic oncologic surgery, irradiation and/or chronic indwelling ureteral stents presenting with intermittent (micro)hematuria. A multidisciplinary consultation is necessary for diagnosis and treatment. The most sensitive test is angiography and the preferred initial treatment is endovascular.

A Uremic Goat Model Created by Subtotal Renal Artery Embolization and Gentamicin.

A large animal model of (end-stage) kidney disease (ESKD) is needed for the preclinical testing of novel renal replacement therapies. This study aimed to create stable uremia via subtotal renal artery embolization in goats and induce a temporary further decline in kidney function by administration of gentamicin. Renal artery embolization was performed in five Dutch white goats by infusing polyvinyl alcohol particles in branches of the renal artery, aiming for the embolization of ~80% of one kidney and complete embolization of the contralateral kidney. Gentamicin was administered to temporarily further increase the plasma concentrations of uremic toxins. After initial acute kidney injury, urea and creatinine plasma concentrations stabilized 1.5 ± 0.7 months post-embolization and remained elevated (12 ± 1.4 vs. 5.6 ± 0.8 mmol/L and 174 ± 45 vs. 65 ± 5.6 µmol/L, resp.) during follow-up (16 ± 6 months). Gentamicin induced temporary acute-on-chronic kidney injury with a variable increase in plasma concentrations of small solutes (urea 29 ± 15 mmol/L, creatinine 841 ± 584 µmol/L, phosphate 2.2 ± 0.3 mmol/L and potassium 5.0 ± 0.6 mmol/L) and protein-bound uremic toxins representative of patients with ESKD. A uremic goat model characterized by stable moderate uremia was established via subtotal renal artery embolization with the induction of temporary severe acute-on-chronic kidney injury by the administration of gentamicin, allowing preclinical in vivo validation of novel renal replacement technologies.

Predicting the presence of macrovascular causes in non-traumatic intracerebral haemorrhage: the DIAGRAM prediction score.

OBJECTIVE: A substantial part of non-traumatic intracerebral haemorrhages (ICH) arises from a macrovascular cause, but there is little guidance on selection of patients for additional diagnostic work-up. We aimed to develop and externally validate a model for predicting the probability of a macrovascular cause in patients with non-traumatic ICH. METHODS: The DIagnostic AngioGRAphy to find vascular Malformations (DIAGRAM) study (n=298; 69 macrovascular cause; 23%) is a prospective, multicentre study assessing yield and accuracy of CT angiography (CTA), MRI/ magnetic resonance angiography (MRA) and intra-arterial catheter angiography in diagnosing macrovascular causes in patients with non-traumatic ICH. We considered prespecified patient and ICH characteristics in multivariable logistic regression analyses as predictors for a macrovascular cause. We combined independent predictors in a model, which we validated in an external cohort of 173 patients with ICH (78 macrovascular cause, 45%). RESULTS: Independent predictors were younger age, lobar or posterior fossa (vs deep) location of ICH, and absence of small vessel disease (SVD). A model that combined these predictors showed good performance in the development data (c-statistic 0.83; 95% CI 0.78 to 0.88) and moderate performance in external validation (c-statistic 0.66; 95% CI 0.58 to 0.74). When CTA results were added, the c-statistic was excellent (0.91; 95% CI 0.88 to 0.94) and good after external validation (0.88; 95% CI 0.83 to 0.94). Predicted probabilities varied from 1% in patients aged 51-70 years with deep ICH and SVD, to more than 50% in patients aged 18-50 years with lobar or posterior fossa ICH without SVD. CONCLUSION: The DIAGRAM scores help to predict the probability of a macrovascular cause in patients with non-traumatic ICH based on age, ICH location, SVD and CTA.

Seven tesla MRI improves detection of focal cortical dysplasia in patients with refractory focal epilepsy.

Objective: The aim of this study is to determine whether the use of 7 tesla (T) MRI in clinical practice leads to higher detection rates of focal cortical dysplasias in possible candidates for epilepsy surgery. Methods: In our center patients are referred for 7 T MRI if lesional focal epilepsy is suspected, but no abnormalities are detected at one or more previous, sufficient-quality lower-field MRI scans, acquired with a dedicated epilepsy protocol, or when concealed pathology is suspected in combination with MR-visible mesiotemporal sclerosis-dual pathology. We assessed 40 epilepsy patients who underwent 7 T MRI for presurgical evaluation and whose scans (both 7 T and lower field) were discussed during multidisciplinary epilepsy surgery meetings that included a dedicated epilepsy neuroradiologist. We compared the conclusions of the multidisciplinary visual assessments of 7 T and lower-field MRI scans. Results: In our series of 40 patients, multidisciplinary evaluation of 7 T MRI identified additional lesions not seen on lower-field MRI in 9 patients (23%). These findings were guiding in surgical planning. So far, 6 patients underwent surgery, with histological confirmation of focal cortical dysplasia or mild malformation of cortical development. Significance: Seven T MRI improves detection of subtle focal cortical dysplasia and mild malformations of cortical development in patients with intractable epilepsy and may therefore contribute to identification of surgical candidates and complete resection of the epileptogenic lesion, and thus to postoperative seizure freedom.

Diagnostic yield and accuracy of CT angiography, MR angiography, and digital subtraction angiography for detection of macrovascular causes of intracerebral haemorrhage: prospective, multicentre cohort study.

STUDY QUESTION: What are the diagnostic yield and accuracy of early computed tomography (CT) angiography followed by magnetic resonance imaging/angiography (MRI/MRA) and digital subtraction angiography (DSA) in patients with non-traumatic intracerebral haemorrhage? METHODS: This prospective diagnostic study enrolled 298 adults (18-70 years) treated in 22 hospitals in the Netherlands over six years. CT angiography was performed within seven days of haemorrhage. If the result was negative, MRI/MRA was performed four to eight weeks later. DSA was performed when the CT angiography or MRI/MRA results were inconclusive or negative. The main outcome was a macrovascular cause, including arteriovenous malformation, aneurysm, dural arteriovenous fistula, and cavernoma. Three blinded neuroradiologists independently evaluated the images for macrovascular causes of haemorrhage. The reference standard was the best available evidence from all findings during one year's follow-up. STUDY ANSWER AND LIMITATIONS: A macrovascular cause was identified in 69 patients (23%). 291 patients (98%) underwent CT angiography; 214 with a negative result underwent additional MRI/MRA and 97 with a negative result for both CT angiography and MRI/MRA underwent DSA. Early CT angiography detected 51 macrovascular causes (yield 17%, 95% confidence interval 13% to 22%). CT angiography with MRI/MRA identified two additional macrovascular causes (18%, 14% to 23%) and these modalities combined with DSA another 15 (23%, 18% to 28%). This last extensive strategy failed to detect a cavernoma, which was identified on MRI during follow-up (reference strategy). The positive predictive value of CT angiography was 72% (60% to 82%), of additional MRI/MRA was 35% (14% to 62%), and of additional DSA was 100% (75% to 100%). None of the patients experienced complications with CT angiography or MRI/MRA; 0.6% of patients who underwent DSA experienced permanent sequelae. Not all patients with negative CT angiography and MRI/MRA results underwent DSA. Although the previous probability of finding a macrovascular cause was lower in patients who did not undergo DSA, some small arteriovenous malformations or dural arteriovenous fistulas may have been missed. WHAT THIS STUDY ADDS: CT angiography is an appropriate initial investigation to detect macrovascular causes of non-traumatic intracerebral haemorrhage, but accuracy is modest. Additional MRI/MRA may find cavernomas or alternative diagnoses, but DSA is needed to diagnose macrovascular causes undetected by CT angiography or MRI/MRA. FUNDING, COMPETING INTERESTS, DATA SHARING: Dutch Heart Foundation and The Netherlands Organisation for Health Research and Development, ZonMw. The authors have no competing interests. Direct requests for additional data to the corresponding author.

Safety of a dedicated brain MRI protocol in patients with a vagus nerve stimulator.

Although implanted metallic devices constitute a relative contraindication to magnetic resonance imaging (MRI) scanning, the safety of brain imaging in a patient with a vagus nerve stimulator (VNS) is classified as "conditional," provided that specific manufacturer guidelines are followed when a transmit and receive head coil is used at 1.5 or 3.0 Tesla. The aim of this study was to evaluate the safety of performing brain MRI scans in patients with the VNS. From September 2009 until November 2011, 101 scans were requested in 73 patients with the VNS in The Netherlands. Patients were scanned according to the manufacturer's guidelines. No patient reported any side effect, discomfort, or pain during or after the MRI scan. In one patient, a lead break was detected based on device diagnostics after the MRI-scan. However, because no system diagnostics had been performed prior to MR scanning in this patient, it is unclear whether MR scanning was responsible for the lead break. The indication for most scans was epilepsy related. Twenty-six scans (26%) were part of a (new) presurgical evaluation and could probably better have been performed prior to VNS implantation. Performing brain MRI scans in patients with an implanted VNS is safe when a modified MRI protocol is followed.

Artefacts induced by coiled intracranial aneurysms on 3.0-Tesla versus 1.5-Tesla MR angiography--An in vivo and in vitro study.

OBJECTIVE: To compare metal-induced artefacts from coiled intracranial aneurysms on 3.0-Tesla and 1.5-Tesla magnetic resonance angiography (MRA), since concerns persist on artefact enlargement at 3.0Tesla. MATERIALS AND METHODS: We scanned 19 patients (mean age 53; 16 women) with 20 saccular aneurysms treated with coils only, at 1.5 and 3.0Tesla according to standard clinical 3D TOF-MRA protocols containing a shorter echo-time but weaker read-out gradient at 3.0Tesla in addition to intra-arterial digital subtraction angiography (IA-DSA). Per modality two neuro-radiologists assessed the occlusion status, measured residual flow, and indicated whether coil artefacts disturbed this assessment on MRA. We assessed relative risks for disturbance by coil artefacts, weighted kappa's for agreement on occlusion levels, and we compared remnant sizes. For artefact measurements, a coil model was created and scanned with the same protocols followed by 2D MR scans with variation of echo-time and read-out gradient strength. RESULTS: Coil artefacts disturbed assessments less frequently at 3.0Tesla than at 1.5Tesla (RR: 0.3; 95%CI: 0.1-0.8). On 3.0-Tesla MRA, remnants were larger than on 1.5-Tesla MRA (difference: 0.7mm; 95%CI: 0.3-1.1) and larger than on IA-DSA (difference: 1.0mm; 95%CI: 0.6-1.5) with similar agreement on occlusion levels with IA-DSA for both field strengths (κ 0.53; 95%CI: 0.23-0.84 for 1.5-Tesla MRA and IA-DSA; κ 0.47; 95%CI: 0.19-0.76 for 3.0-Tesla MRA and IA-DSA). Coil model artefacts were smaller at 3.0Tesla than at 1.5Tesla. The echo-time influenced artefact size more than the read-out gradient. CONCLUSIONS: Artefacts were not larger, but smaller at 3.0Tesla because a shorter echo-time at 3.0Tesla negated artefact enlargement. Despite smaller artefacts and larger remnants at 3.0Tesla, occlusion levels were similar for both field strengths.

How frequent are radiological abnormalities in patients with psychosis? A review of 1379 MRI scans.

BACKGROUND: The term psychosis refers to a combination of symptoms, without pointing to the origin of these symptoms. In a subset of psychotic patients, symptoms are attributable to an organic disease. It is important to identify these organic causes of psychosis early, as urgent treatment of the primary disease may be required. Some of these underlying organic disorders can be identified on magnetic resonance imaging (MRI) scans. Whether routine screening for all psychotic patients should therefore include MRI scans is still a matter of debate. METHODS: This study investigated the prevalence of clinically relevant abnormalities detected on MRI scans from psychotic patients and a matched control group. We could include MRI scans from 656 psychotic patients and 722 controls. The standard radiological reports of these scans were classified as normal, as a nonrelevant abnormality or as a clinically relevant brain abnormality by means of consensus, blind to diagnosis. RESULTS: A normal aspect of the brain was reported in 74.4% of the patients and in 73.4% of the controls. We found clinically relevant pathology in 11.1% of the patients and in 11.8% of the controls. None of the neuropathological findings observed in the patients was interpreted as a possible substrate for organic psychosis. Brain abnormalities that were classified as not clinically relevant were identified in 14.5% of the patients and in 14.8% of the controls. CONCLUSIONS: This suggests that MRI brain scans are not an essential part of routine screening for psychotic patients.

Coil-treated aneurysms: decision making regarding additional treatment based on findings of MR angiography and intraarterial DSA.

PURPOSE: To assess whether magnetic resonance (MR) angiography can be used as a noninvasive alternative to intraarterial digital subtraction angiography (DSA) to indicate additional treatment in the follow-up of patients with coil-treated intracranial aneurysms. MATERIALS AND METHODS: This was an ethics committee-approved multicenter study. Consecutive patients who were scheduled for follow-up intraarterial DSA after coil placement were invited for additional MR angiography after providing written informed consent. Interventional neuroradiologists gave treatment advice (additional treatment, extended follow-up imaging, or discharge from follow-up) for each imaging modality. Agreement between treatment advices based on intraarterial DSA and MR angiographic findings and interobserver agreement were assessed with weighted κ statistics. RESULTS: Agreement between intraarterial DSA- and MR angiography-based treatment recommendations was substantial (κ = 0.73; 95% confidence interval [CI]: 0.66, 0.80). In 34 of the 310 patients (11%), the advice was additional treatment based on findings of both modalities. In six patients (2%), the advice based on intraarterial DSA findings was additional treatment, while that based on MR angiographic findings was extended follow-up imaging; therefore, none of these patients were discharged from follow-up on the basis of MR angiographic findings. In six other patients (2%), the advice based on MR angiographic findings was additional treatment, while that based on intraarterial DSA findings was extended follow-up imaging (four patients), discharge from follow-up (one patient), and noninterpretable DSA (one patient). Extended follow-up imaging was suggested for 37 patients (12%) after intraarterial DSA and for 49 patients (16%) after MR angiography (difference: 4%; 95% CI: -0.6%, 8.4%). Interobserver agreement was substantial for intraarterial DSA (κ = 0.73; 95% CI: 0.64, 0.82) and moderate for MR angiography (κ = 0.53; 95% CI: 0.36, 0.70). CONCLUSION: The overall proportion of patients advised to undergo additional treatment is similar based on intraarterial DSA and MR angiographic findings, with only few individual discrepancies. MR angiography can therefore be used for therapeutic decision making in the follow-up of patients with coil-treated aneurysms. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112608/-/DC1.

Late reopening of adequately coiled intracranial aneurysms: frequency and risk factors in 400 patients with 440 aneurysms.

BACKGROUND AND PURPOSE: In aneurysms that are adequately occluded 6 months after coiling, the risk of late reopening is largely unknown. We assessed the occurrence of late aneurysm reopening and possible risk factors. METHODS: From January 1995 to June 2005, 1808 intracranial aneurysms were coiled in 1675 patients at 7 medical centers. At 6 months, 1066 aneurysms in 971 patients were adequately occluded. At mean 6.0 years after coiling, of the 971 patients, 400 patients with 440 aneurysms underwent 3 Tesla magnetic resonance angiography to assess occlusion status of the aneurysms. Proportions and corresponding 95% CI of aneurysm reopening and retreatment were calculated. Risk factors for late reopening were assessed by univariate and multivariate logistic regression analysis, and included patient sex, rupture status of aneurysms, aneurysm size≥10 mm, and aneurysm location. RESULTS: In 11 of 400 patients (2.8%; 95% CI, 1.4-4.9%) with 440 aneurysms (2.5%; 95% CI, 1.0-4.0%), late reopening had occurred; 3 reopened aneurysms were retreated (0.7%; 95% CI, 0.2-1.5%). Independent predictors for late reopening were aneurysm size≥10 mm (OR 4.7; 95% CI, 1.3-16.3) and location on basilar tip (OR 3.9; 95% CI, 1.1-14.6). There were no late reopenings in the 143 anterior cerebral artery aneurysms. CONCLUSIONS: For the vast majority of adequately occluded intracranial aneurysms 6 months after coiling (those<10 mm and not located on basilar tip), prolonged imaging follow-up within the first 5 to 10 years after coiling does not seem beneficial in terms of detecting reopened aneurysms that need retreatment. Whether patients might benefit from screening beyond the 5- to 10-year interval is not yet clear.

Internal motion of the vagina after hysterectomy for gynaecological cancer.

BACKGROUND AND PURPOSE: The purpose of this study was to investigate position changes of the vagina after hysterectomy for early stage cervical or endometrial cancer and their impact on CTV-PTV margins. We also studied their correlation with surrounding organ filling. MATERIALS AND METHODS: Fifteen patients underwent T2-weighted MR scans before and weekly during the course of their EBRT. The vaginal CTVs and the surrounding organs were delineated. PTV margins were derived from the boundaries of the CTVs in the main directions and correlated with changes in the volumes of organs at risk. Additionally we investigated the impact of margin sizes on CTV coverage. RESULTS: The vaginal CTVs change their position in the pelvis during time with a maximum in anterior-posterior direction. The 95% confidence level was 2.3 cm into the anterior or posterior direction, 1.8 cm to left or right and 1.5 cm towards the cranial. With a homogenous 1.5 cm CTV-PTV margin ≥5% inadequately covered vaginal CTV was seen in only 3.3% of the measurements. This increased to 20.6% with a margin of 1.0 cm. Concerning the impact of organ filling on vaginal position changes we found the only significant correlation with rectal volume and shift of the vagina towards anterior-posterior. CONCLUSION: To accommodate the changes in the position of the vaginal CTV inhomogeneous PTV margins should be generated with the largest size in the anterior-posterior direction. The position shifts were only weakly related to the volume of the rectum and not at all to the volumes of other parts of the bowel and the bladder.

De novo aneurysm formation and growth of untreated aneurysms: a 5-year MRA follow-up in a large cohort of patients with coiled aneurysms and review of the literature.

BACKGROUND AND PURPOSE: Rates of development of de novo intracranial aneurysms and of growth of untreated additional aneurysms are largely unknown. We performed MRA in a large patient cohort with coiled aneurysms at 5-year follow-up. METHODS: In 276 patients with coiled intracranial aneurysms and 5±0.5 years of follow-up MRA (totaling 1332 follow-up patient-years), additional aneurysms were classified as unchanged, grown, de novo, or incomparable with previous imaging. We calculated 5-year cumulative incidence of de novo aneurysm formation and growth of untreated aneurysms. We searched PubMed and EMBASE databases for studies assessing aneurysm development, and growth. RESULTS: In 50 of 276 patients (18%), 75 additional aneurysms were present at follow-up MRA. Of these 75, 2 were de novo (both 3 mm), 58 were unchanged, 5 had grown from 1 to 3 mm (7.9% of 63 known additional aneurysms; 95% CI, 1.3%-14.6%), and 10 were incomparable. Five-year cumulative incidence for a de novo aneurysm developing was 0.75%. Four additional aneurysms in 3 patients were treated. Ten previous studies reported annual incidences of growth of additional aneurysms ranging from 1.51% to 22.7%, and 5 studies reported annual incidences of de novo aneurysm formation ranging from 0.3 to 1.8%. CONCLUSIONS: MRA screening of patients with coiled aneurysms within the first 5 years after treatment has a low rate of de novo aneurysm development and growth of additional aneurysms, and an even lower treatment rate.

The influence of the b-value combination on apparent diffusion coefficient based differentiation between malignant and benign tissue in cervical cancer.

PURPOSE: To analyze the influence of different b-value combinations on apparent diffusion coefficient (ADC)-based differentiation of known malignant and benign tissue in cervical cancer patients. MATERIALS AND METHODS: A total of 35 patients with stage IB1, IB2, IIA cervical cancer underwent a 3.0T MRI scan prior to radical hysterectomy and pelvic lymph node dissection. Conventional T1- and T2-weighted sequences and a diffusion-weighted sequence (b = 0, 150, 500, 1000 seconds/mm(2)) were performed. Regions-of-interest (ROI) were drawn on ADC maps derived from five different b-value combinations (0, 500; 0, 150, 500; 0, 1000; 0, 150, 500, 1000; 150, 500, 1000 seconds/mm(2)). The influence of the b-value combination on ADC-based differentiation of benign and malignant tissue was analyzed using receiver-operating-characteristics curves. RESULTS: For all b-value combinations, ADCs were significantly lower (P < 0.001) in cervical malignancies (1.15 +/- 0.21.10(-3); 1.10 +/- 0.21.10(-3); 0.97 +/- 0.18.10(-3); 0.97 +/- 0.23.10(-3) and 0.85 +/- 0.18.10(-3) mm(2)/second respectively to the aforementioned b-value combinations) than in benign cervix (2.08 +/- 0.31.10(-3); 2.00 +/- 0.29.10(-3); 1.62 +/- 0.23.10(-3); 1.54 +/- 0.21.10(-3) and 1.42 +/- 0.22.10(-3) mm(2)/second respectively). The diagnostic accuracy was high for all b-value combinations and without statistical differences between the combinations. CONCLUSION: ADC-based differentiation of benign from malignant cervical tissue is independent of the tested b-value combinations. The results support the inclusion and possible pooling of studies using different b-value combinations in meta-analyses on ADC-based tissue differentiation in cervical cancer.

Intracranial aneurysms treated with coil placement: test characteristics of follow-up MR angiography--multicenter study.

PURPOSE: To determine the test characteristics of magnetic resonance (MR) angiography in the assessment of occlusion of aneurysms treated with coil placement. MATERIALS AND METHODS: This was an ethics committee-approved multicenter study. written informed consent was obtained in 311 patients with 343 aneurysms, who had been treated with coil placement and were scheduled for routine follow-up with intraarterial digital subtraction angiography (DSA). Thirty-five patients participated two or three times. Either 3.0- or 1.5-T time-of-flight (TOF) and contrast material-enhanced MR angiography were performed in addition to intraarterial DSA. Aneurysm occlusion was evaluated by independent readers at DSA and MR angiography. The test characteristics of MR angiography were assessed by using DSA as the standard. The area under the receiver operating characteristic curve (AUC) was calculated for 3.0- versus 1.5-T MR angiography and for TOF versus contrast-enhanced MR angiography, and factors associated with discrepancies between MR angiography and DSA were assessed with logistic regression. RESULTS: Aneurysm assessments (n = 381) at DSA and MR angiography were compared. Incomplete occlusion was seen at DSA in 88 aneurysms (23%). Negative predictive value of MR angiography was 94% (95% confidence interval [CI]: 91%, 97%), positive predictive value was 69% (95% CI: 60%, 78%), sensitivity was 82% (95% CI: 72%, 89%), and specificity was 89% (95% CI: 85%, 93%). AUCs were similar for 3.0- (0.90 [95% CI: 0.86, 0.94]) and 1.5-T MR (0.87 [95% CI: 0.78, 0.95]) and for TOF MR (0.86 [95% CI: 0.81, 0.91]) versus contrast-enhanced MR (0.85 [95% CI: 0.80, 0.91]). A small residual lumen (odds ratio, 2.1 [95% CI: 1.1, 4.3]) and suboptimal projection at DSA (odds ratio, 5.5 [95% CI: 1.5, 21.0]) were independently associated with discordance between intraarterial DSA and MR angiography. CONCLUSION: Documentation of good diagnostic performance of TOF MR angiography at both 1.5 and 3.0 T in the current study represents an important step toward replacing intraarterial DSA with MR angiography in the follow-up of patients with aneurysms treated with coils.

Inferior caval vein thrombosis owing to compression of focal nodular hyperplasia: surgical resection after shrinkage by hepatic artery embolization.

The purpose of this study was to investigate the results of a staged treatment of symptomatic focal nodular hyperplasia (FNH), consisting of first embolization and then resection. A 36-year-old woman presented with pulmonary embolism caused by an inferior caval vein thrombosis owing to external compression by FNH in liver segment I (5.2 x 6.7 cm). She was treated with anticoagulants. The FNH lesion was first reduced by radiologic embolization of the feeding branch of the right hepatic artery. A 41% size reduction was obtained, and the symptoms disappeared. FNH resection was performed 5(1/2) months later. The thrombus had disappeared, and the anticoagulant therapy could be stopped perioperatively. A symptomatic FNH lesion was treated successfully in two stages.

3T versus 1.5T phased-array MRI in the presurgical work-up of patients with partial epilepsy of uncertain focus.

PURPOSE: To study 3T compared to 1.5T phased array magnetic resonance imaging (MRI) in the presurgical work-up of patients with epilepsy with complex focus localization. MATERIALS AND METHODS: In all, 37 patients (>10 years) in preoperative work-up for epilepsy surgery were offered 3T in addition to 1.5T MRI if ambiguity existed about the epileptic focus. Scans were randomly reviewed by two observers, blinded for prior imaging, patient-identifying information, and each other's assessments, followed by a consensus meeting. The number of abnormal scans, detected lesions, and interobserver agreement were calculated and compared. The final consensus was compared to original scan reports. RESULTS: One observer identified 22 lesions in both 3 and 1.5T scans, while the second identified more lesions in 1.5T scans (28 vs. 20). 3T MRI had better interobserver agreement. 3T revealed more dysplasias, while 1.5T revealed more tissue loss and mesial temporal sclerosis (MTS). The final consensus yielded 29 lesions, whereas original reports identified only 17 lesions. CONCLUSION: The 3T scans revealed different lesions compared to 1.5T. Patients can benefit most from 3T scans when a dysplasia is suspected. Reevaluation by another experienced neuroradiologist is advised in case of negative or equivocal MRIs.

Motion and deformation of the target volumes during IMRT for cervical cancer: what margins do we need?

BACKGROUND AND PURPOSE: For cervical cancer patients the CTV consists of multiple structures, exhibiting complex inter-fraction changes. The purpose of this study is to use weekly MR imaging to derive PTV margins that accommodate these changes. MATERIALS AND METHODS: Twenty patients with cervical cancer underwent a T2-weighted MRI exam before and weekly during IMRT. The CTV, GTV and surrounding organs were delineated. PTV margins were derived from the boundaries of the GTV and CTV in the six main directions and correlated with changes in the volumes of organs at risk. RESULTS: Around the GTV a margin of 12, 14, 12, 11, 4 and 8mm to the anterior, posterior, right lateral, left lateral, superior and inferior directions was needed. The CTV required margins of 24, 17, 12, 16, 11 and 8 mm. The shift of the GTV and CTV in the AP directions correlated weakly with the change in rectal volume. For the bladder the correlations were even weaker. CONCLUSIONS: We used weekly MRI scans to derive inhomogeneous PTV margins that accommodate changes in GTV and CTV. The weak correlations with rectum and bladder volume suggest that measures to control filling status of these organs may not be very effective.

Image-guided vascular neurosurgery based on three-dimensional rotational angiography. Technical note.

Three-dimensional rotational angiography is capable of exquisite visualization of cerebral blood vessels and their pathophysiology. Unfortunately, images obtained using this modality typically show a small region of interest without exterior landmarks to allow patient-to-image registration, precluding their use for neuronavigation purposes. The aim of this study was to find an alternative technique to enable 3D rotational angiography-guided vascular neurosurgery. Three-dimensional rotational angiograms were obtained in an angiographic suite with direct navigation capabilities. After image acquisition, a navigated pointer was used to touch fiducial positions on the patient's head. These positions were located outside the image volume but could nevertheless be transformed into image coordinates and stored in the navigation system. Prior to surgery, the data set was transferred to the navigation system in the operating room, and the same fiducial positions were touched again to complete the patient-to-image registration. This technique was tested on a Perspex phantom representing the cerebral vascular tree and on two patients with an intracranial aneurysm. In both the phantom and patients, the neuronavigation system provided 3D images representing the vascular tree in its correct orientation, that is, the orientation seen by the neurosurgeon through the microscope. In one patient, tissue shift was clearly observed without significant changes in the orientation of the structures. Results in this study demonstrate the feasibility of using 3D rotational angiography data sets for neuronavigation purposes. Determining the benefit of this type of navigation should be the subject of future studies.