Surgery for Glioblastoma in Light of Molecular Markers: Impact of Resection and MGMT Promoter Methylation in Newly Diagnosed IDH-1 Wild-Type Glioblastomas

BACKGROUND

Previous studies addressing the influence of surgery on the outcome of patients with glioblastomas (GBM) have not addressed molecular markers. The value of surgery versus the tumor's major biological markers remains unclear.

OBJECTIVE

We investigate the extent of resection as a prognosticator for patients with newly diagnosed primary GBM with the incorporation of molecular diagnostics as per the updated WHO 2016 diagnostic criteria for GBM.

METHODS

Patients with newly diagnosed GBM who underwent resection were prospectively included within a database. We analyzed patients with newly diagnosed GBM and excluded patients who presented with IDH1 R132H mutations. Gross total resection (GTR) was defined as complete removal of enhancing disease.

RESULTS

One hundred seventy-five patients were included within the analysis. One hundred four patients (59.4%) had GTR, 71 patients (40.6%) had subtotal or partial resection. Eighty patients (45.7%) displayed O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation, 95 patients (54.3%) showed no MGMT promoter methylation. In Cox regression analysis, MGMT promoter methylation (hazard ratio [HR] 1.55; 95% confidence interval [CI], 1.01-2.19; P = .0133) and GTR (HR 1.48; 95% CI, 1.06-2.07; P = .0206) were significantly associated with favorable progression-free survival. MGMT promoter methylation (HR 2.13; 95% CI, 1.45-3.12; P = .0001) and GTR (HR 1.81; 95% CI, 1.24-2.63; P = .002) were associated with favorable overall survival (OS). Of other risk factors analyzed, age (>60 vs ≤ 60 yr) was significantly associated with progression-free survival (HR 1.60; 95% CI, 1.14-2.24; P = .006) and OS (HR 2.19; 95% CI, 1.51-3.19; P < .0001).

CONCLUSION

GTR and MGMT promoter methylation are independent prognosticators for improved overall and progression-free survival in a homogeneous cohort of newly diagnosed patients with IDH wild-type glioblastoma.

Assessment of molecular markers demonstrates concordance between samples acquired via stereotactic biopsy and open craniotomy in both anaplastic astrocytomas and glioblastomas

The classification, treatment and prognosis of high-grade gliomas has been shown to correlate with the expression of molecular markers (e.g. MGMT promotor methylation and IDH1 mutations). Acquisition of tumor samples may be obtained via stereotactic biopsy or open craniotomy. Between the years 2009 and 2013, 22 patients initially diagnosed with HGGs via stereotactic biopsy, that ultimately underwent open craniotomy for resection of their tumor were prospectively included in an institutional glioma database. MGMT promotor analysis was performed using methylation-specific (MS)-PCR and IDH1R132H mutation analysis was performed using immunohistochemistry. Three patients (13.7%) exhibited IDH1R132H mutations in samples obtained via stereotactic biopsy. Tissue derived from stereotaxic biopsy was demonstrated to have MGMT promotor methylation in ten patients (45.5%), while a non-methylated MGMT promotor was demonstrated in ten patients (45.5%); inconclusive results were obtained for the remaining two patients (9%) within our cohort. The initial histologic grading, IDH1R132H mutation and MGMT promotor methylation results were confirmed using samples obtained during open craniotomy in all but one patient; here inconclusive MGMT promotor analysis was obtained in contrast to that which was obtained via stereotactic biopsy. Tumor samples acquired via stereotactic biopsy provide accurate information with regard to clinically relevant molecular markers that have been shown to impact patient care decisions. The profile of markers analyzed in our cohort was nearly concordant between those samples obtained via stereotactic biopsy or open craniotomy thereby suggesting that clinical decisions may be based on the molecular profile of the tumor samples obtained via stereotactic biopsy.

Intracranial Ameloblastoma Arising from the Maxilla: An Interdisciplinary Surgical Approach

Background Ameloblastomas are a rare tumor entity accounting for only 10% of all odontogenic tumors. They mostly originate from the mandible. Only a few cases are known to grow aggressively and to invade the orbit, nasal cavity, or even the brain. Patient and Methods/Case Report We present the case of a 57-year-old patient who was admitted with a huge tumor involving the nasal cavity, the left maxilla, and the anterior fossa. Histologic diagnosis was made by biopsy. A combined two-stage neurosurgical maxillofacial approach was planned. First the intracranial tumor mass was removed using bifrontal trepanation. A duraplasty was sewn in to cover the brain. In the second procedure, a combined bifrontal and midfacial approach was used by craniofacial plastic surgeons and neurosurgeons. A perisinusoidal tumor mass and retropharyngeal tumor mass was removed up to the skull base. The left orbit was completely exenterated, and a fibular bone-muscle graft was used for palatal, orbital, and facial reconstruction. The facial vein and artery were carefully prepared to feed the bone-muscle graft by end-to-end anastomoses. Conclusion Ameloblastomas are very rare slow-growing tumors that show a tendency to recur. They are responsible for only 1% of all oral tumors. Their growth can be enormous, and they can extend into sinusoidal cavities, the orbit, and the brain. Complex and extensive palliative surgery can ease the concerns of these patients and prolong their survival.

Time-resolved 3D rotational angiography: display of detailed neurovascular anatomy in patients with intracranial vascular malformations

PURPOSE

The purpose of this pilot study was to demonstrate the applicability of time-resolved three-dimensional (3D) reconstructions from 3D digital subtraction angiography (DSA) rotational angiography (RA) datasets (four-dimensional (4D) DSA) to provide a more detailed display of the architecture of intracranial vascular malformations.

METHODS

The experimental reconstruction software was applied to the existing 3D DSA datasets obtained with Siemens Artis zee biplane neuroangiography equipment. We included 27 patients with clinical indications for 3DRA for preinterventional or preoperative evaluation of intracranial dural arteriovenous fistulas (dAVFs, n=8) or arteriovenous malformations (AVMs, n=19). A modified DSA acquisition protocol covering an extended rotation angle of the C-arm of 260° during a scan time of 12 s was used. 4D volumes were displayed with up to 30 frames/s in a transparent volume rendering (VRT) mode and time-resolved multiplanar reconstructions (MPRs). Arterial feeders, fistulous points, or the shunt zone within the AVM nidus and venous drainage patterns as well as associated aneurysms were assessed after definition of a standardized evaluation procedure by consensus of two reviewers in comparison with 2D DSA and conventional 3D reconstructions.

RESULTS

In all cases calculation of 4D reconstructions were technically feasible and evaluable. In two cases image quality was slightly compromised by movement artifacts. Compared with standard DSA projection images and 3D reconstructions, 4D VRTs and MPRs were rated significantly superior to define a proper projection and display of the shunt zone. In 12 out of 27 cases 4D reconstructions showed details of the angioarchitecture at the fistulous point or the nidus better than the other modalities and came close to the quality of superselective angiography. The efficacy of 3D and 4D applications was equal in the detection of pre- and intranidal aneurysms. The course of long arterial feeders and draining veins was difficult to assess on VRTs and MPRs. Especially for dAVFs, 2D DSA was clearly superior in identifying meningeal feeders. For detecting smaller vessels and for distinction between angiographic phases, 2D DSA is still considered to be superior to 4D imaging. Venous drainage was slightly better displayed in 4D reconstructions.

CONCLUSIONS

Time-resolved 3DRA with 4D VRTs and MPRs is technically feasible and provides a detailed display of the angioarchitecture at the fistulous point or the nidus. Visualization of all angiographic features demands additional post-processing. Further standardization of evaluation tools and studies with blinded independent reviewers are necessary before the new technique can replace conventional neuroangiographic approaches.

Stereotactic biopsy of brainstem lesions: 21 years experiences of a single center

Stereotactic biopsies are procedures performed to obtain tumor tissue for diagnostic examinations. Cerebral lesions of unknown entities can safely be accessed and tissue can be examined, resulting in correct diagnosis and according treatment. Stereotactic procedures of lesions in highly eloquent regions such as the brainstem have been performed for more than two decades in our department. In this retrospective study we focus on results, approaches, modalities of anesthesia, and complications. We performed a retrospective analysis of our prospective database, including 26 patients who underwent stereotactic biopsy of the brainstem between April 1994 and June 2015. All of the patients underwent preoperative MRI. Riechert-Mundinger-frame was used before 2000, thereafter the Leksell stereotactic frame was used. After 2000 entry and target points were calculated by using BrainLab stereotactic system. We evaluated histopathological results as well as further treatment; additionally we compared complications of local versus general anesthesia and complications of a frontal versus a trans-cerebellar approach. Median age of all patients was 33 years, and median number of tissue samples taken was 12. In all patients a final histopathological diagnosis could be established. 5 patients underwent the procedure under local anesthesia, 21 patients in general anesthesia. In 19 patients a frontal approach was performed, while in 7 patients a trans-cerebellar approach was used. Complications occurred in five patients. Thereby no significant difference was found with regard to approach (frontal versus trans-cerebellar) or anesthesia (local versus general). Stereotactic biopsies even of lesions in the brainstem are a save way to obtain tumor tissue for final diagnosis, resulting in adequate treatment. Approach can be trans-cerebellar or frontal and procedure can be performed either under local or general anesthesia without significant differences concerning complication rate.

Benefit of Stereotactic Procedures in a Series of 43 Children

OBJECTIVES

Stereotactic biopsies are procedures that enable neurosurgeons to obtain tissue samples of brain tumors located in eloquent areas with a low risk of perioperative complications. In this study, we examined stereotactic procedures (STX) in children. We focused on effectiveness, safety, and histopathological results to evaluate the benefits of the procedure.

METHODS

We performed a retrospective analysis of our prospective database and included 43 children aged less than 18 years who underwent STX between 1998 and May 2015. All MRIs were evaluated by a single, experienced neuroradiologist. For all biopsies, Leksell stereotactic frame was used and fixed to the children's head with four pins. Entry and targetpoints were calculated by BrainLab navigation system. We assessed age, tumor localization, number of samples, histological diagnosis, and postoperative treatment.

RESULTS

Median age of the patients was 11 years (range 1-18 years), and median number of tissue samples taken was 12 (range 1 with mere puncture of a cyst to 36). Histopathological examination revealed a final diagnosis in all patients. 3 patients underwent puncture of a cyst. 27 patients had a postoperative imaging. Only in 3 patients, CT scan revealed blood in the area where the biopsy had been taken. All bleedings were small and without clinical sequelae.

CONCLUSION

Stereotactic procedures are accurate and save surgeries to obtain tumor tissue from eloquent areas to base further therapy on. This not only applies to adults but also to children of all ages.

Cerebral vasospasm and delayed cerebral infarctions in 225 patients with non-aneurysmal subarachnoid hemorrhage: the underestimated risk of Fisher 3 blood distribution

OBJECTIVE

Recent data have shown increasing numbers of non-aneurysmal subarachnoid hemorrhage (NASAH). However, data are limited and often only small series have been published. Our objective was to analyze the rate of cerebral vasospasm (CVS), delayed cerebral infarction (DCI), and their influence on the clinical outcome, especially in patients with diffuse Fisher 3 bleeding pattern NASAH (Fi3).

METHODS

Between 1999 and 2014, 225 patients had NASAH. CVS, DCI, and outcome (according to the modified Rankin Scale at 6 months) were analyzed retrospectively. Patients were stratified according to the bleeding type. After univariate analysis a multivariate analysis was performed and NASAH Fi3 was also compared with aneurysmal SAH Fi3.

RESULTS

Patient characteristics and the outcome of perimesencephalic (PM) and non-PM (NPM) SAH were similar. Excluding Fi3, PM and NPM without Fi3 had similar patient characteristics, clinical course, and outcome. In particular, the Fi3 subgroup had a significantly increased risk of CVS, DCI, unfavorable outcome, hydrocephalus, and death. Early hydrocephalus was associated with Fi3 and intraventricular hemorrhage. The multivariate regression model showed the variables elderly patients, Fi3, and early hydrocephalus as independent and significant predictors for an unfavorable outcome. A further comparison of NASAH Fi3 with aneurysmal SAH Fi3 showed similar characteristics, CVS rate, and mortality.

CONCLUSIONS

Patients with NASAH without a Fi3 bleeding pattern had a similar excellent outcome to patients with PM-SAH. Patients with Fi3 had a high risk for early hydrocephalus, CVS, DCI, and an unfavorable outcome, similar to patients with aneurysmal SAH. After multivariate analysis, early hydrocephalus, elderly patients, and Fi3 were identified as negative prognostic factors. Therefore, patients with Fi3 are at risk and need careful clinical observation.

A novel reconstruction tool (syngo DynaCT Head Clear) in the post-processing of DynaCT images to reduce artefacts and improve image quality

BACKGROUND

Latest generations of flat detector (FD) neuroangiography systems are able to obtain CT-like images of the brain parenchyma. Owing to the geometry of the C-arm system, cone beam artifacts are common and reduce image quality, especially at the periphery of the field of view. An advanced reconstruction algorithm (syngo DynaCT Head Clear) tackles these artifacts by using a modified interpolation-based 3D correction algorithm to improve image quality.

MATERIALS AND METHODS

Eleven volumetric datasets from FD-CT scans were reconstructed with the standard algorithm as well as with the advanced algorithm. In a two-step data analysis process, two reviewers compared dedicated regions of the skull and brain in both reconstruction modes using a 5-point scale (1, much better; 5, much worse; advanced vs standard algorithm). Both reviewers were blinded to the reconstruction mode. In a second step, two additional observers independently evaluated image quality of the 3D data (non-comparative evaluation) in dedicated regions also using a 5-point scale (1, not diagnostically evaluable; 5, good quality, perfectly usable for diagnosis) for both reconstruction algorithms.

RESULTS

Both in the comparative evaluation of dedicated brain regions and in the independent analysis of the FD-CT datasets the observers rated a better image quality if the advanced algorithm was used. The improvement in image quality was statistically significant at both the supraganglionic (p=0.018) and the infratentorial (p=0.002) levels.

CONCLUSIONS

The advanced reconstruction algorithm reduces typical artifacts in FD-CT images and improves image quality at the periphery of the field of view.

Combination of 5-ALA and iMRI in re-resection of recurrent glioblastoma

Background Tumour resection plays a role in the initial treatment but also in the setting of recurrent glioblastoma (rGBM). To achieve maximum resection, 5-aminolevulinic acid (5-ALA) and intraoperative MRI (iMRI) are used as surgical tools. Aiming at complete tumour re-resection, we started combining iMRI with 5-ALA to find out if this leads to better surgical results. Methods We performed tumour resections in seven patients with rGBM, combining 5-ALA (20 mg/kg bodyweight) with iMRI (0.15 T). Radiologically complete resections were intended in all seven patients. We assessed intraoperative fluorescence findings and compared these with intraoperative imaging. All patients had early postoperative MRI (3 T) to verify final iMRI scans and received adjuvant treatment according to interdisciplinary tumour board decision. Results Median patient age was 63 years. Median KPS score was 90, and median tumour volume was 8.2 cm(3). In six of seven patients (85%), 5-ALA induced fluorescence of tumour-tissue was detected intraoperatively. All tumours were good to visualise with iMRI and contrast media. One patient received additional resection of residual contrast enhancing tissue on intraoperative imaging, which did not show fluorescence. Radiologically complete resections according to early postoperative MRI were achieved in all patients. Median survival since second surgery was 7.6 months and overall survival since diagnosis was 27.8 months. Conclusions 5-ALA and iMRI are important surgical tools to maximise tumour resection also in rGBM. However, not all rGBMs exhibit fluorescence after 5-ALA administration. We propose the combined use of 5-ALA and iMRI in the surgery of rGBM.

Analysis of T2 signal intensity helps in the differentiation between high and low-grade brain tumours in paediatric patients

PURPOSE

Previous studies hypothesized that the analysis of magnetic resonance intensity of the solid portion in paediatric tumours can provide pre-surgical information about the histopathology. Classically, high signal-intensity in T2weighted (T2w) images identifies low-grade tumours, while anaplasia is characterized by T2 hypointensity. We aimed to investigate if T2w signal intensities can pre-operatively distinguish between low-grade and high-grade brain tumours in paediatric patients.

METHODS

Two raters, blinded to the histological diagnosis, rated the signal intensity of MR images (T2w) from 36 children with newly diagnosed brain tumours, 17 children with low-grade brain tumours and 19 children with high-grade brain tumours were included in this study. Relative T2 values were obtained by dividing the T2w values of the solid portion of the tumour by the T2w values of the vitreous humour.

RESULTS

The best cut-off point to distinguish low and high-grade paediatric brain tumours was 0.8. If the signal intensity was less than or equal to 0.8 the tumour was expected to be a high-grade tumour with a sensitivity of 100%. Prediction of a low-grade tumour was more uncertain with a sensitivity of 70.5%. Overall, 86% of the tumours would have been predicted correctly.

CONCLUSION

Our data suggest that T2w signal intensities of the solid portion of brain tumours in paediatrics can pre-operatively differentiate between low-grade and high-grade tumours. In addition, T2 hypointensity may be helpful in targeting stereotactic biopsy.

Evaluation of the perforators of the anterior communicating artery (AComA) using routine cerebral 3D rotational angiography

Background

Damage to perforating branches of the anterior communicating artery (AComA) is a known complication of surgical or interventional treatment procedures for AComA aneurysm leading to neurologic deficits. In spite of the clinical relevance of these AComA branches, they have not been systematically analyzed using imaging techniques and most of our knowledge is based on post-mortem injection studies or neurosurgical reports. We therefore analyzed three-dimensional rotational angiography (3DRA) images of the AComA, and propose a first imaging definition of the microvascular structures surrounding the AComA.

Methods

Reconstructed 3D data derived from standard-of-care rotational angiography acquisitions (5 s DSA) were retrospectively analyzed. 20 patients undergoing selective cerebral angiography and 3DRA for therapy assessment were included in our study. 3DRA datasets were reconstructed and displayed using the volume rendering technique (VRT). Additionally, multiplanar reformatted CT-like cross-sectional images (MPR) were used to evaluate the number, size, and origin of the perforators of the AComA.

Results

Perforating branches of the AComA could be demonstrated in all cases with large interindividual variations in vessel visibility. MPRs appeared to be superior to total VRT volumes in the visualization of the perforating branches of the AComA.

Conclusions

3DRA can be used to visualize perforating branches of the AComA in vivo. Since damage to these perforators may result in neurologic deficits, visualization of these vessels prior to surgery or endovascular aneurysm treatment could help in the planning of therapeutic interventions. Further refinement of current imaging techniques will be necessary, however, to increase the reliability of small vessel angiography.

Endovascular and surgical treatment of internal carotid bifurcation aneurysms: comparison of results, outcome, and mid-term follow-up

BACKGROUND

Aneurysms of the internal carotid artery (ICA) bifurcation are rare, and no studies have compared patient outcomes after endovascular vs surgical treatment.

OBJECTIVE

To report the safety, efficacy, and follow-up outcome of these 2 treatment options for patients with ICA bifurcation aneurysms.

METHODS

Patient and aneurysm characteristics, treatment results, and follow-up outcomes (at 30 months) were analyzed from patient records and review of imaging findings.

RESULTS

A total of 58 patients with ICA bifurcation aneurysms were treated. By interdisciplinary consensus, 30 aneurysms were assigned for coiling and 28 for clipping. Patients who underwent surgical clipping were younger and had larger aneurysms. More patients were assigned to coiling if their aneurysms originated only from the ICA bifurcation or projected superiorly. For the combined angiographic endpoint, complete and nearly complete occlusion (Raymond-Roy I + II), similar rates of 96% (coiling) or 100% (clipping) could be achieved. Raymond-Roy I occlusion occurred more often after clipping (79% vs 41% coiling). Follow-up of the endovascular group showed minor recanalization of the aneurysm neck (Raymond-Roy II) in 42%. One patient (4%) showed a major recanalization (Raymond-Roy III) and needed re-treatment. For incidental findings, no bleeding complications or new persistent neurological deficits occurred during follow-up.

CONCLUSION

Treatment of ICA bifurcation aneurysms after interdisciplinary assignment to clipping or coiling is effective and safe. Despite significantly more minor recanalizations after coiling, the re-treatment rate was very low, and no bleeding was observed during follow-up. Multivariate analysis revealed that origin only from the ICA bifurcation was an independent predictor of aneurysm recanalization after endovascular treatment.

Impact of Stereotactic Biopsy in HIV Patients

OBJECTIVE

During their disease a significant number of human immunodeficiency virus (HIV)-infected patients develop neurologic symptoms due to intracerebral pathologies. Entities commonly found are toxoplasmosis, lymphomas, or progressive multifocal leukoencephalopathy. In some patients, diagnosis is not feasible with imaging alone, requiring biopsy. The objective of this study was to evaluate the impact of stereotactic biopsy in HIV patients on adjustment of therapy.

METHODS

Between January 2004 and May 2015 at our clinic, 26 HIV-infected patients underwent stereotactic biopsy. Thin-layer magnetic resonance images were obtained and fused with computed tomography scans, taken with the stereotactic frame (Leksell) mounted. Biopsy material was evaluated pathologically and microbiologically.

RESULTS

Histologic analysis revealed B-cell lymphoma in 6 patients (23.1%) and progressive multifocal leukoencephalopathy in 2 patients (7.7%). Abscess and toxoplasmosis were found in 3 patients each (11.5% and 11.5%), and encephalitis occurred in 4 patients (15.4%). In 2 patients each (7.7%), vasculitis, metastasis, and glioblastoma were diagnosed. Further findings comprised non-Hodgkin lymphoma and Burkitt lymphoma in 1 patient each. After biopsy, treatment was significantly changed in 18 (69.2%) patients (P < 0.01). Antibiotic therapy was adjusted in 6 patients (23.1%), and chemotherapy in 3 patients (16.7%). Other changes included antibiotic/antiviral therapy to chemotherapy in 3 patients (16.7%), chemotherapy to radiation, cortisone to chemotherapy, and aciclovir to cortisone in 1 patient each. One patient with glioblastoma underwent resection, and another patient received radiation. One patient underwent palliative care.

CONCLUSION

Stereotactic biopsy in HIV-infected patients results in significant changes of therapy in more than two thirds of the patients.

Misleading FLAIR imaging pattern after glioma surgery with intraoperative MRI

Intraoperative MRI (iMRI) allows a more detailed appreciation of the extent of resection than does conventional neurosurgery and results in longer overall survival in patients with malignant glioma. However, it is unknown whether the intraoperative application of contrast agent influences the early postsurgical MRI. The preceding iMRI could alter the signals of MR sequences in the early postsurgical MRI, especially in sequences influenced by T1 contrast. Hereby, we investigate such iMRI-induced influences on the fluid-attenuated inversion recovery (FLAIR) sequence. We retrospectively analyzed postsurgical T2w, T1w, and FLAIR images by visual inspection and by signal measurements in 46 patients with malignant gliomas after tumor resection. Of these, n = 25 patients were operated with conventional microsurgery, and n = 21 patients were operated with contrast-enhanced iMRI-guided microsurgery. We measured signal intensity in the resection cavity, in the cerebrospinal fluid (CSF) of the ventricles, and in the normal brain tissue contralateral to the tumor-bearing hemisphere on axial FLAIR images and T1-weighted and T2-weighted images. In 18 patients, the FLAIR sequence revealed hyperintense signal changes of the CSF in the subarachnoid or ventricular spaces. Seventeen of these 18 patients had received intraoperative MRI. In both FLAIR and T1-weighted images, the signal of the CSF in the ventricles was significantly higher in patients with iMRI than in patients without iMRI. The intraoperative application of contrast agent that is used for iMRI significantly influences postsurgical MRI within the first 72 h. We found hyperintense signal changes of the CSF in the FLAIR sequence in the subarachnoid and intraventricular spaces mimicking subarachnoid hemorrhage. The findings may result in a misdiagnosis of subarachnoid hemorrhage (SAH) in these patients.

Time window for postoperative reactive enhancement after resection of brain tumors: less than 72 hours

Object

Early postoperative MRI within 72 hours after brain tumor surgery is commonly used to assess residual contrast-enhancing tumor. The 72-hour window is commonly accepted because previous 1.5-T MRI studies have not found confounding postoperative reactive contrast enhancement in this time frame. The sensitivity to detect contrast enhancement increases with the field strengths. Therefore, the authors aimed to assess whether the 72-hour window is also appropriate for the MRI scanner with a field strength of 3 T.

Methods

The authors retrospectively analyzed findings on early postsurgical MR images acquired in 46 patients treated for high-grade gliomas. They performed 3-T MRI within 7 days before surgery and within 72 hours thereafter. The appearance of enhancement was categorized as postoperative reactive enhancement or tumoral enhancement by comparison with the pattern and location of presurgical enhancing tumor.

Results

Postoperative reactive enhancement was present in 15 patients (32.6%). This enhancement, not seen on presurgical MRI, had a marginal or leptomeningeal/dural pattern. In 13 patients (28.3%) postsurgical enhancement was found within the first 72 postoperative hours, with the earliest seen 22:57 hours after surgery. Subsequent MR scans in patients with postoperative reactive enhancement did not reveal tumor recurrence in these regions.

Conclusions

Postoperative reactive enhancement earlier than 72 hours after brain tumor surgery can be expected in about one-third of the cases in which a 3-T scanner is used. This might be due to the higher enhancement-to-brain contrast at higher field strengths. Therefore, the time window of 72 hours does not prevent reactive enhancement, which, however, can be recognized as such comparing it with presurgical enhancing tumor.

Evaluation of the pontine perforators of the basilar artery using digital subtraction angiography in high resolution and 3D rotation technique

BACKGROUND AND PURPOSE

Compromise of perforating branches of the basilar artery resulting in brain stem infarctions has been described as a major complication of intracranial stent placement for basilar artery stenosis or after implantation of endovascular flow diverters. Descriptions of pontine arteries are mainly based on examinations of injection specimens; however, there is a lack of consistent presentation of the small branches of the basilar artery in the imaging literature. Therefore, we retrospectively analyzed DSA images and 3D rotational angiography with a review of literature for an imaging definition of microvascular anatomy of the brain stem.

MATERIALS AND METHODS

We retrospectively analyzed 2k DSA images (detector format 32 × 32 cm; image matrix 2480 × 1920 pixels) and 3D rotational angiography reconstructions (5 second DSA, subtraction technique) obtained on Axiom Artis zee biplane neuroradiologic angiography equipment using standard protocol.

RESULTS

On 2D and 3D DSA images, small arterial side branches of the basilar artery can be demonstrated in each of the cases but with a wide variation in the visibility of these vessels. Compared with 2D DSA images, 3D DSA reconstructions allow superior visualization of the small branches of the basilar artery.

CONCLUSIONS

Our results demonstrate that 2D DSA and 3D-rotation techniques are able to reliably visualize the penetrating branches of the brain stem in vivo. No zone of basilar artery is free from important side branches. Collateral pathways between circumferential and perforating arteries are occasionally detectable. In the future, further refinement of imaging techniques is necessary to increase the reliability of small vessel angiography to use this data for risk assessment before stent placement and aneurysm treatment.

Isometric non-machine-based prevention training program: effects on the cross-sectional area of the paravertebral muscles on magnetic resonance imaging

PURPOSE

The purpose of this study was to determine potential effects of isometric non-machine-based training on the cross-sectional area (CSA) of the paravertebral muscles in volunteers who were participants in a prevention program. An increase in the CSA of back muscles after various machine-based exercises have been reported but non-machine-based training programs have not been adressed before.

MATERIALS AND METHODS

In the study 14 volunteers, who were participants of a company internal prevention program, underwent a magnetic resonance (MR) examination before and after a 3 months training program to improve back muscle strength. The MRI protocol consisted of T1-weighted and T2-weighted images aligned to the intervertebral disc spaces. The CSAs of the erector spinae and quadratus lumborum muscles were assessed twice by 2 operators at the levels L3/4, L4/5 and L5/S1.

RESULTS

Out of 14 subjects 11 completed the training. The recorded CSA values exhibited an intrarater and intrarater correlation coefficient ranging from 0.949 to 0.989. There was an increase in CSA in all subjects after the training period (mean increase 8%).

CONCLUSIONS

A 3-month isometric training program is sufficient to effect measurable increases in back muscles volume. The study demonstrated the usefulness of MRI to quantify such changes as a measure of training efficacy and compliance into the training program. These results represent a rationale for further studies to determine the effect of different training methods on the CSA of back muscles and to correlate structural changes with clinical symptoms in chronic low back pain syndrome.