Application of a novel metal artifact correction algorithm in flat-panel CT after coil embolization of brain aneurysms: intraindividual comparison.

PURPOSE: To evaluate a novel algorithm for correcting beam hardening artifacts caused by metal implants in computed tomography performed on a C-arm angiography system equipped with a flat panel (FP-CT). MATERIALS AND METHODS: 16 datasets of cerebral FP-CT acquisitions after coil embolization of brain aneurysms in the context of acute subarachnoid hemorrhage have been reconstructed by applying a soft tissue kernel with and without a novel reconstruction filter for metal artifact correction. Image reading was performed in multiplanar reformations (MPR) in average mode on a dedicated radiological workplace in comparison to the preinterventional native multisection CT (MS-CT) scan serving as the anatomic gold standard. Two independent radiologists performed image scoring following a defined scale in direct comparison of the image data with and without artifact correction. For statistical analysis, a random intercept model was calculated. RESULTS: The inter-rater agreement was very high (ICC = 86.3 %). The soft tissue image quality and visualization of the CSF spaces at the level of the implants was substantially improved. The additional metal artifact correction algorithm did not induce impairment of the subjective image quality in any other brain regions. CONCLUSION: Adding metal artifact correction to FP-CT in an acute postinterventional setting helps to visualize the close vicinity of the aneurysm at a generally consistent image quality.

Radiographic examination of patients with dehiscence of semicircular canals with digital volume tomography.

Digital volume tomography (DVT) is an extension of panoramic tomography. With this diagnostic technique, characterized by high resolution, a narrow section width (0.125 mm), and three-dimensional display, small pathological processes can be well visualized. We examined 434 patients with DVT (Accu-I-tomo, Morita, Japan). Eleven patients with a history of peripheral vertigo presented a fistula of the labyrinth. The results were compared with intraoperative findings to evaluate the diagnostic value of DVT in cases of erosion of the semicircular canals. With high resolution and artifact-free demonstration of the labyrinth and inner ear structures, it was possible to determine the presence of a fistula of the semicircular canals in all 11 patients. An erosion of the lateral semicircular canal was found in nine patients with additional fistulae of the superior and posterior semicircular canals in one patient, a dehiscence of bone of the superior semicircular canal in one patient, and a dehiscence of the posterior semicircular canal in another patient. The predicted erosion of semicircular canals was verified in all patients during surgery where a closure of the fistulae was performed. DVT is an excellent technique to examine the semicircular canal structures in patients with peripheral vertigo, and expand the application of diagnostic possibilities in the lateral skull base. With this method, the preoperative diagnosis is improved allowing more accurate planning of the surgical procedure. DVT delivers a small radiation dose with a high resolution and a low purchase price for the equipment.

Measurement and comparison of labyrinthine structures with the digital volume tomography: ancient Egyptian mummies' versus today's temporal bones.

The objective of this study was to investigate whether the labyrinthine structures of ancient Egyptian mummies differ significantly from modern labyrinths. The new technique of digital volume tomography (DVT) was used to visualize the temporal bones. To obtain standardized images and measurements, precise instructions regarding volume rotation, slicing and measurements' positioning were determined. Twenty-five dimensions were obtained. The groups were compared statistically. No significant differences could be found except one cochlear diameter which proved to be significantly larger in the control group. DVT is applicable for imaging of temporal bones. Measurements might help to increase understanding of the temporal bone's structure, to aid the diagnostics of pathologies as well as to supplement the planning of surgical procedures.

Imaging of ancient Egyptian mummies' temporal bones with digital volume tomography.

The radiographic imaging of ancient Egyptian mummies has always been of great interest. Computed tomography is the method of choice to demonstrate bony pathologies with high quality. As digital volume tomography (DVT) is an extension of panoramic tomography with a very high resolution, its qualities were evaluated by examination of temporal bones of Egyptian mummy skulls. Ten Egyptian mummy skulls from the Zoological Collection Marburg, estimated 1,700-5,000 years of age, from Abydos, Philae, Theben-West and Sakkarah, were examined by DVT (3D Accuitomo, Morita, Japan). Through a rotation 360° of the X-ray source around the region of interest, a cylinder of 3 × 4 cm was captured as a three-dimensional volume. The gained data were analyzed with the help of special software on a PC. The angles of the axial, coronal and sagittal sections were arbitrarily changed to represent single structures with high resolution of 0.125 mm to analyze specific anatomical structures. In all skulls, conditions of the temporal bone and its anatomical structures were evaluated and normal as well as pathological findings evaluated in detail. The analysis of special landmarks such as the ossicular chain, cochlea, external, and internal auditory canal, facial nerve canal, and semicircular canals showed an intact ossicular chain in six temporal bones, while only isolated and dislocated ossicles were found in eight temporal bones. Besides one dehiscence of the superior semicircular canal in one temporal bone which might have led to vertigo and deafness at lifetime, all other findings were normal. Fragments of foreign bodies additionally found in the labyrinth, external ear canal and intracranially were attributed to postmortem damage. Digital volume tomography extends the imaging possibilities of CT for paleoradiological evaluation of temporal bones. With its high resolution, geometric accuracy, reconstruction capabilities, rapidness, and comparably low costs, even small bony pathologies are precisely demonstrated in a limited area. Investigations of larger numbers of specimen might reveal further details of ancient history for further interdisciplinary investigation of anthropologists, Egyptiologists, otolaryngologists, and radiologists.

Diagnostic and therapeutic considerations for "mycotic" cerebral aneurysms: 2 case reports and review of the literature.

OBJECTIVE: Cerebral aneurysms of an infectious etiology, so-called "mycotic" aneurysms, are rare neurovascular pathologies. Primary treatment may be targeted on the aneurysm, but care has to be driven by the underlying pathology to prevent an often fatal clinical course with a mortality rate reaching 90%. 2 case reports are presented, and the diagnostic and therapeutic issues outlined by reviewing the literature. CASE REPORT: A 33-year-old female was admitted to our hospital with a sudden left-sided hemiparesis following a 3-week history of fever. An atypical intracerebral hemorrhage of the right parietal lobe due to a ruptured aneurysm of the distal middle cerebral artery (MCA) was diagnosed. Blood cultures containing Streptococcus sanguinus were the only finding for an infectious origin. Antibiotic therapy was started, followed by neurosurgical evacuation of the hematoma and clipping of the aneurysm. In a second case, endovascular coiling was the choice of treatment in a 38-year-old male presenting with a distal bifurcation aneurysm of the frontal MCA insular branch. An aortic valve replacement had been previously performed due to a congenital heart condition. The primary site of infection remained unclear and a 4-week course of broad-spectrum antibiotics was given intravenously. DISCUSSION: Cerebral aneurysms far distal to the usual sites of congenital aneurysms, organisms in blood chemistry, endocarditis, symptoms of infection, atypically located intracerebral hemorrhages, and young patients with immunodeficiency are strong factors for an infectious aneurysm. Cerebral angiography is mandatory to exclude aneurysms at other sites and early targeted antimicrobial treatment is crucial in these cases. Elimination of the aneurysm itself should be evaluated carefully because treating these aneurysms remains challenging compared to the ordinary group of cerebral aneurysms. Reconstructive procedures without sacrificing the parent artery often fail due to the fusiform and fragile aneurysm wall. CONCLUSION: Cerebral aneurysms of an infectious origin often have a disastrous clinical course in which morbidity and mortality can be reduced by early diagnosis, appropriate antimicrobial therapy, and aneurysm elimination by an experienced team. Apart from the initial treatment, major attention should be focused on a thorough follow-up to confirm complete cure of the primary site of infection.

How to deal with incompletely treated AVMs: experience of 67 cases and review of the literature.

INTRODUCTION: Despite the availability of multimodal treatment options, some arteriovenous malformations remain difficult to treat, either for intrinsic reasons at initial presentation or for reasons evolving during the course of treatment. Frequently, such cases can be easily resolved with further therapy, but some become a continuously growing treatment dilemma while exhausting dwindling therapeutic options. PATIENTS AND METHODS: A retrospective analysis was performed to identify patients with cerebral AVM who were treated unsuccessfully. Treatment was termed "not successful" if (1) postoperative angiography showed a residual AVM or missing flow reduction after palliative embolization, (2) therapy was associated with a substantial deterioration of existing neurological deficits or death, or (3) rebleeding from residual AVM occurred after therapy. Special interest was focused on the angiographic appearance of residual AVMs, their characteristic features, and their follow-up regarding second and third therapies. RESULTS: According to these criteria we identified 46 internal patients from our own series of 474 patients and 21 external patients who were referred from other institutions or sought a second opinion after incomplete treatment elsewhere. Out of those 67 cases, 50 patients (74.6%) were diagnosed with a residual AVM. Eleven patients (16.4%) experienced a deterioration of their clinical condition under therapy. Six patients did not show a flow reduction after palliative embolization. Twenty-five of the 67 patients were readmitted because of an ICH, either originating from an AVM residual or under palliative embolization. Thus, an increased risk of re-hemorrhage was found for palliative embolization (n = 16) in partially treated lesions (n = 10) and in patients with AVM grade IV and V located in eloquent regions (n = 22). In dealing with residual AVMs, microsurgical resection alone or in combination was found to be the most efficient therapeutic option, being successful in 58.9% of cases. CONCLUSION: An estimated 10% of AVM treatments may fail because of inadequate selection of either patients or management. Besides, for thorough decision-making, angiographic follow-up in all AVM patients is mandatory to allow an early identification of patients with an incompletely treated AVM requiring a second attempt. Major attention should be focused especially on high-risk subgroups with complex AVMs, partially treated AVMs, or those treated by only a palliative regimen.

Therapeutic clues in spinal dural arteriovenous fistulas - a 30 year experience of 156 cases.

BACKGROUND: Spinal dural arteriovenous fistulae (SDAVF) are rare but remain the most common type of spinal vascular malformations. Treatment options for SDAVF include endovascular embolization, microsurgical dissection or a combination of both. But the optimal treatment paradigm has yet to be defined and may well be an individualized interdisciplinary combinatorial approach. MATERIAL AND METHODS: From 1980 to 2008, 156 patients with the diagnosis of SDAVF were treated by neuroradiological and neurosurgical means. Based on the procedure-related complications we retrospectively analyzed our data to elucidate the reasons for endovascular failure and the evolution of the surgical technique. RESULTS: 156 patients were included in this study. There were 31 (19.9%) female and 125 (80.1%) male patients. Average age at the time of diagnosis was 60.8 years. 102 out of 156 (65.4%) underwent endovascular obliteration, 54 (34.6%) patients were treated primarily by surgery. 134 (85.9%) underwent follow-up examination. A total of 29 (18.6%) out of 156 patients could not be treated successfully by endovascular (9.4%) or surgical (4.1%) means. CONCLUSION: Microsurgery can be recommended as the first choice treatment when the fistula's point is unmistakably identified intradurally. Endovascular obliteration may be justifiable in cases with an easy access to a monoradicular feeding artery during diagnostic angiography. Surgery is a definitive treatment with stable long-term results in which procedure-related morbidity is low. During evolution of the combined approach, endovascular coil placement for correct localization of the fistula and the use of intraoperative micro-Doppler was found to be very helpful in increasing the safety of the surgical procedure and minimizing surgical exposure.

[Certified quality management according to DIN ISO 9001 in a radiology department at a university hospital: measurable changes in academic quality indicators?]. / Qualitätsmanagement nach DIN ISO 9001 an einer radiologischen Universitätsklinik: Messbare Veränderungen der universitären Kennzahlen nach der Zertifizierung?

PURPOSE: To evaluate the changes in academic quality indicators after implementation of a quality management system according to DIN ISO 9001:2000. MATERIALS AND METHODS: After implementation and certification of a quality management system, the actual state based on quality indicators from the fields of student teaching, research, continuing education and the satisfaction of referring physician was determined. After implementation of an action plan for the individual areas, the temporal changes in the ratios were documented in the follow-up. RESULTS: The evaluation of teaching performance obtained by questionnaire among the students of the radiology course showed a steady increase in satisfaction (mean value 2003: 2.7; 2007: 3.9). In the field of research an increase in scientific output was achieved based on the number of an internal publication score (2002: 99 points; 2006: 509). Repeated opinion surveys among our referring physicians found improvements in indicators for the appointment of investigations, consulting service and waiting times for the investigation, while the waiting times for internal transport service did not improve. Exemplary measurements of the success of the advanced training of the staff demonstrated the need for continuing education for quality improvement. CONCLUSION: The evaluation of quality indicators showed over time a measurable positive impact on processes of a radiological University Hospital after implementation of a QM system according to DIN ISO 9001:2000.

[Long-term outcome after endovascular treatment of high-risk patients with recurrently symptomatic intracranial stenoses of the posterior circulation]. / Langzeitergebnisse nach endovaskulärer Behandlung von Hochrisiko-Patienten mit mehrfach symptomatischen intrakraniellen Stenosen der vertebrobasilären Strombahn.

PURPOSE: We present long-term clinical and duplex data from high-risk patients with severe, recurrent symptomatic stenoses of the vertebrobasilar circulation. We hypothesized that despite the greater risk of periprocedural complications in this patient group, interventional treatment would reduce the risk of recurrent strokes relative to the expected natural risk. We also predicted that the long-term treatment outcome would be positively influenced by the use of stents and by the periprocedural technical success rate. MATERIALS AND METHODS: An analysis of our patient data base yielded 45 cases of stenosis of the vertebrobasilar circulation treated endovascularly in 42 patients between 1998 and 2006. Clinical and vascular diagnostic tests, both periinterventionally and during follow-up, were performed independently by experienced neurologists. RESULTS: The technical success rate was 93%. Stents were used in 67% of the procedures. After 30 days, 24% of the patients showed post-procedural clinical deterioration. After an average period of 26.3 months, 17.8 % of the patients had deteriorated. 11.1% of the patients suffered severe permanent damage as a result of the procedure (mRs 3 - 6). Restenosis was found in 9.5% of the cases. There were no instances of a recurrent stroke during follow-up. CONCLUSION: For this population of high-risk patients with recurrently symptomatic intracranial stenoses of the vertebrobasilar axis, endovascular treatment reduced the risk of stroke and death relative to the expected natural risk. The use of stents had no significant effect on the long-term results.

Territorial and microvascular perfusion impairment in brain arteriovenous malformations.

BACKGROUND AND PURPOSE: Both the existence and clinical relevance of a steal phenomenon in brain arteriovenous malformations (AVMs) remains a matter of debate. This study aimed to assess perfusion in the brain adjacent to brain AVMs and to relate these to macrovascular blood flow in a single measurement. MATERIALS AND METHODS: Twenty consecutive patients with AVMs with a median age of 37 years were evaluated by 3T MR imaging by using 3D time-resolved MR angiography to determine blood flow and perfusion patterns. Cerebral perfusion was estimated by using an arterial spin-labeling technique in vascular territories around the nidus and in symmetric regions of interest in the ipsilateral and contralateral hemispheres. Mapping of concentric shells around the nidus was used to define the immediate and adjacent brain and relative perfusion reductions >20% of baseline, termed perinidal dip (PND). RESULTS: A significant reduction in perfusion ratios between ipsilateral and contralateral hemispheres remote to the AVMs was demonstrated in the middle and posterior cerebral artery territories. PND was detected in 5 patients, and 17 patients overall showed reduced perfusion in the perinidal region on visual inspection. There was a negative correlation of the hemispheric territorial perfusion with the affected/nonaffected inflow time ratio (R = -0.402, P = .015). CONCLUSIONS: The perfusion impairment in vascular territories adjacent to brain AVMs that we identified as PND may reflect the existence of 2 levels of perfusion impairment: a territorial and a microvascular perfusion disturbance. Although the hemispheric asymmetry in territorial perfusion seems the result of arterioarterial redistribution, the PND was inhomogeneously distributed within a single vascular territory and thus might result from low perfusion pressure in small arteries and arterioles.

Long-term outcome after angioplasty of symptomatic internal carotid artery stenosis with and without stent.

INTRODUCTION: Carotid angioplasty and stenting (CAS) has widely replaced balloon angioplasty (percutaneous transluminal angioplasty, PTA) in the treatment of internal carotid artery stenosis (ICAS). Here we assess whether the use of stents increases the safety and long-term efficacy of angioplasty in patients with ICAS. Our aim was to test the hypothesis that the long-term efficacy of CAS is superior to that of PTA. METHODS: At the University Medical Center Hamburg-Eppendorf, PTA was performed from 1990 to 1997 and CAS was performed from 1998 to 2006. All patients undergoing these procedures were symptomatic. Selection and follow-up examinations were performed by independent vascular neurologists. Follow-up terms were 1, 3, 6 and 12 months, then annually. RESULTS: In the PTA group (n=71), 2.8% of the patients showed severe periinterventional complications (i.e. lasting neurological deficits). Of these 71 patients, 57.7% were followed up for an average period of 51 months. Stenosis >70% was observed in 9.8% of the PTA patients, while 4.9% of the patients had ipsilateral occlusions. In the CAS group (n=354), 4.2% of the patients showed severe periinterventional complications. In total, 61% of the CAS patients were followed up for an average period of 25 months, of whom 4.6% showed stenosis of >70% and 1.9% had ipsilateral occlusions. Periprocedural complications and new symptoms that appeared during follow-up occurred at a rate of 5.6% (PTA) and 5.9% (CAS). There was no difference in the rate of annual ipsilateral events (1.1% in PTA vs. 1.3% in CAS, p=1.000) CONCLUSION: Overall, the use of stents, rather than PTA only, shows no beneficial clinical effect in the treatment of ICA stenosis. While the rate of restenosis may be significantly reduced, this merely suggests that the impact of restenosis is less apparent than expected.

Long-term follow-up of cerebral aneurysms after endovascular therapy prediction and outcome of retreatment.

BACKGROUND AND PURPOSE: The purpose of this study was to analyze angiographic and clinical results before and after additional endovascular therapy in patients with previously coiled but reopened cerebral aneurysms and to identify possible risk factors for retreatment of an aneurysm. MATERIALS AND METHODS: Follow-up with selective digital subtraction angiography was performed in 323/596 (54.2%) patients harboring 342 aneurysms with a mean follow-up time of 28.6 months. The patients were divided into 3 groups: group A, who remained stable after initial treatment; group B, who showed minor morphologic changes; and group C, who underwent repeat treatment. Univariate and multivariate regression analyses were performed to determine possible risk factors for aneurysmal retreatment. RESULTS: Single or multiple retreatment was performed in 33 of 323 (10.2%) patients. Retreatment of small aneurysms (< or =10 mm) with small necks (< or =4 mm) was performed in 6 of 214 aneurysms. When summarizing all other aneurysms as a "risk group" (n = 128), the odds ratio (OR) for retreatment in the "risk group" was 3.11 (95% CI: 1.43-6.75; P = .004). In patients with residual aneurysm after the first treatment, OR for retreatment was 3.96 (95% CI: 1.48-10.65; P = .006), whereas a neck remnant, clinical presentation, and aneurysmal localization were not predictive. We observed no resulting morbidity and mortality from the 33 retreatment procedures. CONCLUSION: In our series, the retreatment of aneurysmal recurrences was a safe procedure. The best single predictors of aneurysmal recurrence were aneurysmal anatomy (neck width >4 mm and diameter >10 mm) and the presence of a residual aneurysm after initial treatment. A limitation in our study was the significant number of patients lost to follow-up (22.7%).

Navigation-assisted resection of a primary extraocular melanoma of the orbit.

UNLABELLED: A 22-year-old male presented with proptosis of the right eye and diplopia. On magnetic resonance images (MRI), a well-delineated orbital tumor medio-distal to the eye was detected, respecting the eye-ball and the orbital walls. The aim of navigation-assisted surgery was to excise the progressive tumor while maintaining vision. A modified latero-cranial orbitotomy was used to approach the tumor. Microscopic analysis of the resection specimen revealed a melanoma. The patient's postoperative course was uneventful. The diplopia improved rapidly. Two further eye-saving second-look revisions of the tumor site excluded further melanoma infiltrates and revealed melanophages in scar tissue. Intraoperative navigation was used during all procedures. The tumor showed some interesting features concerning its histopathological appearance and magnetic resonance imaging. Detailed histopathological investigations supported the decision for organ-saving surgery. Follow-up MRI and positron emission tomograms up to 14 months later showed neither local tumor recurrence nor distant spread. CONCLUSION: In the presented case with the incidental finding of orbital melanoma without invasion of the globe or orbital walls, navigation-assisted surgery supported the eye-saving operating procedures.

[Visual rating of T2'-blood-oxygen-level-dependent magnetic resonance imaging in acute stroke patients--a pilot study]. / T2'-Blood-Oxygen-Level-Dependent-Magnetresonanz-Bildgebung beim akuten Schlaganfall--eine Pilotstudie.

PURPOSE: Delineation of brain tissue that is at risk but not yet infarcted (penumbra) continues to be a major challenge for stroke imaging. Metabolic characterization of the penumbra might be able to be achieved using blood-oxygen-level-dependent (BOLD) imaging. MATERIALS AND METHODS: We analyzed MRI data from 20 patients within the first 6 hours after stroke onset and after 5-8 days. Among other sequences, the MRI protocol consisted of diffusion-weighted (DWI/ADC = apparent diffusion coefficient) and quantitative T2 and T2* imaging (qT2, qT2*). BOLD images (T2') were calculated using 1/T2' = 1/qT2* - 1/qT2. BOLD lesions were rated by two blinded observers. RESULTS: Based on the primary blinded reading of the BOLD images, the lesion side was rated correctly by observers 1 and 2 in 80/50 % of the cases, incorrectly in 5/40 % of the cases, and rated as not visible in 15/10 % of the cases. After unblinding the observers, the visibility was rated in 45/45 % of the cases as good, in 35/40 % of the cases as reasonable, and in 20/15 % of the cases as insufficient for diagnostic purposes. The sensitivity for subsequent infarct growth was 0.88 (95 % confidence interval, CI 0.47 to 0.99), the specificity was 0.33 (95 % CI 0.07 to 0.70), the positive predictive value (PPV) was 0.54 (95 % CI 0.25 to 0.81), and the negative predictive value (NPV) was 0.75 (95 % CI 0.19 to 0.99). The odds ratio for subsequent infarct growth was 3.5 (95 % CI 0.20 to 115.53). CONCLUSION: Hypo-intense lesions in BOLD imaging were visible and exceeded the lesion in diffusion-weighted imaging in most of the stroke patients. The encouraging results justify further testing of the hypothesis that BOLD lesions, when larger than DWI lesions, are associated with infarct growth from initial DWI to final infarct.

Surgical treatment of a basilar perforator aneurysm not accessible to endovascular treatment.

Aneurysms originating from perforatoring branches of the midbasilar artery are extremely rare. Rupture of such an aneurysm resulted in a subarachnoid hemorrhage with a prepontine clot in a 44 year old male who presented with an acute confusional state. After coil embolization had failed, the partially thrombosed aneurysm was wrapped and coagulated via a combined supra-/infratentorial subtemporal presigmoid approach in prone position. The postoperative course was complicated by a tension pneumatocephalus and liquorrhea. Additional aneurysms of the anterior communicating artery and right middle cerebral artery were clipped several months later. The patient recovered well, and except for slight gait ataxia no other deficit remained.

[Duplex ultrasound of external carotid artery branches for the detection of dural arteriovenous fistulae]. / Duplexsonographie von A.-carotis-externa-Asten zum Nachweis duraler AV-Fisteln.

PURPOSE: To evaluate duplex ultrasonography of external carotid artery branches for the non-invasive diagnosis of dural AV fistulae (DAVFs). MATERIALS AND METHODS: A total of 126 patients suffering from pulsatile tinnitus underwent duplex ultrasonography of the cervicocephalic vasculature including external carotid artery branches. DAVFs were identified by increased flow velocity and reduced pulsatility. Patients with ultrasound findings of DAVFs were considered for selective angiography. RESULTS: Of the 23 patients that fulfilled the ultrasound criteria of AV fistula, 5 did not undergo angiography and were excluded from the study. The ultrasound findings of AV fistula were confirmed in all remaining patients (17 DAVFs, 1 extracranial AV fistula). Duplex ultrasound detected a DAVF of the common carotid artery in 29 %, of the external carotid artery in 65 % and of the external carotid artery branches in 100 % of the cases. CONCLUSION: Duplex ultrasonography of external carotid artery branches improves the non-invasive detection of DAVFs. For the evaluation of the venous drainage, however, selective angiography is necessary.