Gamma Knife surgery for craniopharyngioma: report on a 20-year experience

Object

Although craniopharyngiomas are benign intracranial tumors, their high recurrence rates and intimate associations with surrounding neurovascular structures make gross tumor resection challenging. Stereotactic radiosurgery has been introduced as a valuable adjuvant therapy for recurrent or residual craniopharyngiomas. However, studies with large patient populations documenting long-term survival and progression-free survival rates are rare in the literature. The current study aims to report the long-term radiosurgical results and to define the prognostic factors in a large cohort of patients with a craniopharyngioma.

Methods

A total of 137 consecutive patients who underwent 162 sessions of Gamma Knife surgery (GKS) treatments at the Taipei Veterans General Hospital between 1993 and 2012 were analyzed. The patients' median age was 30.1 years (range 1.5–84.9 years), and the median tumor volume was 5.5 ml (range 0.2–28.4 ml). There were 23 solid (16.8%), 23 cystic (16.8%), and 91 mixed solid and cystic (66.4%) craniopharyngiomas. GKS was indicated for residual or recurrent craniopharyngiomas. The median radiation dose was 12 Gy (range 9.5–16.0 Gy) at a median isodose line of 55% (range 50%–78%).

Results

At a median imaging follow-up of 45.7 months after GKS, the rates of tumor control were 72.7%, 73.9%, and 66.3% for the solid, cystic, and mixed tumors, respectively. The actuarial progression-free survival rates plotted by the Kaplan-Meier method were 70.0% and 43.8% at 5 and 10 years after radiosurgery, respectively. After repeated GKS, the actuarial progression-free survival rates were increased to 77.3% and 61.2% at 5 and 10 years, respectively. The overall survival rates were 91.5% and 83.9% at the 5- and 10-year follow-ups, respectively. Successful GKS treatment can be predicted by tumor volume (p = 0.011). Among the 137 patients who had clinical follow-up, new-onset or worsened pituitary deficiencies were detected in 11 patients (8.0%). Two patients without tumor growth had a worsened visual field, and 1 patient had a new onset of third cranial nerve palsy.

Conclusions

The current study suggests that GKS is a relatively safe modality for the treatment of recurrent or residual craniopharyngiomas, and it is associated with improved tumor control and reduced in-field recurrence rates. Acceptable rates of complications occurred.

Imaging quality and diagnostic reliability of low-dose computed tomography lumbar spine for evaluating patients with spinal disorders

BACKGROUND CONTEXT

Computed tomography (CT) scans of the lumbar spine (CTLS) have demonstrated a higher level of accuracy than plain films and have been used to assess patients with spinal disorder when magnetic resonance imaging is not available. Nevertheless, radiation exposure remains a serious safety concern. Iterative reconstruction (IR) decreases the CT radiation dose for diagnostic imaging. However, the feasibility of using IR in CTLS is unclear.

PURPOSE

To evaluate the imaging quality and diagnostic reliability of CTLS with IR.

STUDY DESIGN

A prospective study.

PATIENT SAMPLE

All patients from outpatient departments who suffered from spinal disorders and were referred for CTLS.

OUTCOME MEASURES

In acquired CT images, the signal-to-noise ratio (SNR) of the dural sac (DS), intervertebral disc (IVD), psoas muscle (PM), and L5 vertebral body, the contrast-to-noise ratio between the DS and IVD (D-D CNR), and the subjective imaging qualities were compared across groups. Interobserver agreement was evaluated with kappa values.

METHODS

Patients receiving low radiation CTLS were divided into three groups. A 150 mAs tube current with 120 kVp tube voltage was used with Group A and a 230 mAs tube current with 100 kVp tube voltage with Group B. Intended end radiation exposure was 50% less than that of the control group. Tube modulation was active for all groups. The images of the two low-radiation groups were reconstructed by IR; those of the control group by filtered back-projection (FBP).

RESULTS

The SNRs of the DS, IVD, PM, BM, and D-D CNR of Group A were not inferior to those of the control group. All SNRs and D-D CNRs for Group B were inferior to those of the control group. Except for that of the facet joint, all subjective imaging ratings for anatomic regions were equivalent between Groups A and B. Interobserver agreement was highest for the control group (0.72-0.88), followed by Group A (0.69-0.83) and B (0.55-0.83).

CONCLUSIONS

Fifty percent tube current reduction combined with IR provides equivalent diagnostic accuracy and improved patient safety when compared with conventional CTLS. Our results support its use as a screening tool. With the tube modulation technique, further adjustments in weighting IR and FBP algorithms based on body mass index become unnecessary.

Bilobulated paraclinoid aneurysm mimics double aneurysms: a comparison of endovascular coiling and surgical clipping treatments

This report presents two cases of subarachnoid hemorrhage caused by rupture of paraclinoid aneurysms. Both aneurysms presented a bilobulated appearance upon image study. Both cases were treated successfully, the first with surgical clipping and the second with endovascular coiling. The special bilobulated feature of paraclinoid aneurysm in this particular anatomic location suggests its close relationship with the carotid dural ring. This relationship caused varying degrees of difficulty in both coiling and clipping the aneurysm. We compared the limitations and advantages of both treatments, and suggest that surgical clipping may be the treatment of choice in this region.

New grading of moyamoya disease using color-coded parametric quantitative digital subtraction angiography

BACKGROUND

Moyamoya disease (MMD) is an uncommon cerebrovascular disorder characterized by idiopathic progressive stenosis or the occlusion of the intracranial arteries. Digital subtraction angiography (DSA) is the reference diagnostic imaging modality for MMD. Use of the conventional Suzuki grading remains the gold standard for evaluating the severity of MMD. In this study, we propose a quantitative method using color-coded parametric quantitative DSA (QDSA) to improve prediction of the severity of MMD.

METHODS

Eighteen DSA examinations from 18 patients with MMD and 14 control participants were included. All patients with MMD underwent DSA and dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI). QDSA was used to determine the delay time of maximal opacification (Td) between the internal carotid artery and the M2 segment of the middle cerebral artery. The time-to-peak (TTP) was measured in the medial frontal, lateral frontal, parietal, and occipital lobes from the DSC-PWI. The relative TTP (rTTP) values were then obtained by subtracting the TTP of the cerebellum.

RESULTS

The Td was significantly longer in the patients with MMD presenting with infarction than in the control group. The Td significantly correlated with the angiographic Suzuki grading system and showed closer correlation with prolonged rTTP in the medial frontal, lateral frontal, and parietal regions compared with Suzuki grading.

CONCLUSION

The Td significantly correlated with conventional angiographic grading and with the status of hemodynamic impairment in patients with MMD. QDSA and Td measurements can provide a simple and quantitative angiographic grading system for patients with MMD.

Radiation doses of cerebral blood volume measurements using C-arm CT: A phantom study

BACKGROUND AND PURPOSE

Parenchymal blood volume measurement by C-arm CT facilitates in-room peritherapeutic perfusion evaluation. However, the radiation dose remains a major concern. This study aimed to compare the radiation dose of parenchymal blood volume measurement using C-arm CT with that of conventional CTP using multidetector CT.

MATERIALS AND METHODS

A biplane DSA equipped with C-arm CT and a Rando-Alderson phantom were used. Slab parenchymal blood volume (8-cm scanning range in a craniocaudal direction) and whole-brain parenchymal blood volume with identical scanning parameters, except for scanning ranges, were undertaken on DSA. Eighty thermoluminescent dosimeters were embedded into 22 organ sites of the phantom. We followed the guidelines of the International Commission on Radiation Protection number 103 to calculate the effective doses. For comparison, 8-cm CTP with the same phantom and thermoluminescent dosimeter distribution was performed on a multidetector CT. Two repeat dose experiments with the same scanning parameters and phantom and thermoluminescent dosimeter settings were conducted.

RESULTS

Brain-equivalent dose in slab parenchymal blood volume, whole-brain parenchymal blood volume, and CTP were 52.29 ± 35.31, 107.51 ± 31.20, and 163.55 ± 89.45 mSv, respectively. Variations in the measurement of an equivalent dose for the lens were highest in slab parenchymal blood volume (64.5%), followed by CTP (54.6%) and whole-brain parenchymal blood volume (29.0%). The effective doses of slab parenchymal blood volume, whole-brain parenchymal blood volume, and CTP were 0.87 ± 0.55, 3.91 ± 0.78, and 2.77 ± 1.59 mSv, respectively.

CONCLUSIONS

The dose measurement conducted in the current study was reliable and reproducible. The effective dose of slab parenchymal blood volume is about one-third that of CTP. With the advantages of on-site and immediate imaging availability and saving procedural time and patient transportation, slab parenchymal blood volume measurement using C-arm CT can be recommended for clinical application.

Transarterial Onyx embolization of intracranial dural arteriovenous fistulas: a single center experience

BACKGROUND

Transarterial embolization of intracranial dural arteriovenous fistulas (DAVFs) is usually associated with inadequate embolization. The purpose of this study was to report our experience of transarterial Onyx embolization of intracranial DAVFs with an emphasis on treatment outcome with this new embolic agent in different types of DAVFs.

METHODS

In the past 3 years, a total of 14 intracranial DAVFs have been treated by transarterial Onyx embolization. Among these, there were nine males and five females, aged from 30 years to 82 years (mean = 62 years). We retrospectively analyzed the injection volume and time of Onyx embolization as well as outcomes in different types of DAVFs.

RESULTS

The locations of the DAVFs were sigmoid sinus (n = 6), tentorium (n = 3), sinus confluence (n = 2), transverse-sigmoid sinus (n = 1), sigmoid sinus-jugular bulb (n = 1) and the superior petrous sinus (n = 1). The mean volume and time of Onyx injection were 3.4 mL and 28 minutes, respectively (Cognard type I: 4.9 mL, 40 minutes; type II: 4.5 mL, 34 minutes; type III: 2.2 mL, 21 minutes; type IV: 2 mL, 22 minutes). Total fistula occlusion was achieved in six out of seven patients of type III and type IV DAVFs, and in four out of seven patients of type I and type II DAVFs. Nine patients had total resolution of their symptoms, whereas partial regression occurred in five patients. No significant periprocedural complication was found. Mean clinical follow-up period was 16 months.

CONCLUSION

Transarterial Onyx embolization of intracranial DAVFs is safe and effective. This technique is particularly useful in type III and type IV DAVFs with a high cure rate, and lower volume of Onyx as well as a short injection time.

Detection of acute cerebral hemorrhage in rabbits by magnetic induction

Acute cerebral hemorrhage (ACH) is an important clinical problem that is often monitored and studied with expensive devices such as computed tomography, magnetic resonance imaging, and positron emission tomography. These devices are not readily available in economically underdeveloped regions of the world, emergency departments, and emergency zones. We have developed a less expensive tool for non-contact monitoring of ACH. The system measures the magnetic induction phase shift (MIPS) between the electromagnetic signals on two coils. ACH was induced in 6 experimental rabbits and edema was induced in 4 control rabbits by stereotactic methods, and their intracranial pressure and heart rate were monitored for 1 h. Signals were continuously monitored for up to 1 h at an exciting frequency of 10.7 MHz. Autologous blood was administered to the experimental group, and saline to the control group (1 to 3 mL) by injection of 1-mL every 5 min. The results showed a significant increase in MIPS as a function of the injection volume, but the heart rate was stable. In the experimental (ACH) group, there was a statistically significant positive correlation of the intracranial pressure and MIPS. The change of MIPS was greater in the ACH group than in the control group. This high-sensitivity system could detect a 1-mL change in blood volume. The MIPS was significantly related to the intracranial pressure. This observation suggests that the method could be valuable for detecting early warning signs in emergency medicine and critical care units.

Fistula component of cerebral arteriovenous malformations: morphologic change after stereotactic radiosurgery and outcome of embolisation

BACKGROUND

The angioarchitecture of arteriovenous fistulas (AVFs) of cerebral arteriovenous malformation (CAVM) after stereotactic radiosurgery (SRS) remain unclear. The purpose of this study is to report the angiographic change of AVF components of CAVMs after SRS and outcomes of endovascular embolisation.

METHODS

From 2002 to 2012, a total of 523 CAVMs had been treated primarily by SRS with more than 3-year latency. Among these databases, there were 19 patients with 21 AVFs undergoing embolization after SRS. We retrospectively analyzed the angioarchitecture of the CAVM to identify AVFs, morphologic change and outcomes of AVFs after SRS and embolisation.

RESULTS

Eight AVFs were in the periphery of CAVMs, the other 13 were in a central location. Eighteen of 21 AVFs remained constant in morphology after SRS, while three feeders of AVFs were associated with radiation arteritis. The causes of failure to identify AVFs before SRS were overlooked (n = 7) or there was superimposition with feeders, nidus and/or venous drains of CAVMs (n = 14). Total fistula occlusion was achieved in all 21 AVFs; residual CAVMs was totally obliterated by embolisation and/or additional SRS in 12 patients. One patient had a small procedure-related intracerebral hemorrhage. Mean follow-up period was 26 months.

CONCLUSIONS

Early detection of AVF components of CAVMs prior to SRS may be difficult, particularly those in a central location. However, most AVFs became evident and showed consistency in angiographic morphology after obliteration of the majority nidus parts of CAVMs. Endovascular embolisation is effective in managing these AVF components.

Quantitative analysis of digital subtraction angiography using optical flow method on occlusive cerebrovascular disease

BACKGROUND AND PURPOSE

Traditional digital subtraction angiography (DSA) provides detailed spatial resolution in the treatment of cerebrovascular disease. However, the available temporal information is often underutilized. The purpose of this study is to use deformable image registration with DSA to quantify the hemodynamic improvement of intracranial vessels after carotid stenting.

MATERIALS AND METHODS

Eighteen patients with carotid stenosis (greater than 70% degree by NASCET criteria) were treated using percutaneous transluminal angioplasty with stents. Carotid angiograms of the anterior-posterior and lateral views were acquired before and after the treatment. The arterial and venous phases of each single acquisition were classified according to the first arrival time of contrast in the distal middle cerebral artery and the superior sagittal sinus, respectively. The optical flow method was subsequently applied to determine the blood flow velocity in intracranial vessels. Blood flow velocity comparisons were performed to determine the therapeutic effects of blood flow restoration.

RESULTS

The pixel-by-pixel blood flow velocity was estimated using the optical flow method. A color scale was used in the visualization and estimation of the blood flow velocity in the vascular bed. The improvements of blood flow velocity in both the arterial and the venous phases were significant (p<0.05). The changes with contrast agent motion were more easily observed in the arterial phase compared with the venous phases.

CONCLUSION

Quantitative digital subtraction angiography provides reliable blood flow velocity measurements, which facilitates pretherapeutic evaluation and a reliable follow-up analysis method for the evaluation of occlusive vascular disorder treatment in the head and neck regions.

Hemodynamic segmentation of brain perfusion images with delay and dispersion effects using an expectation-maximization algorithm

Automatic identification of various perfusion compartments from dynamic susceptibility contrast magnetic resonance brain images can assist in clinical diagnosis and treatment of cerebrovascular diseases. The principle of segmentation methods was based on the clustering of bolus transit-time profiles to discern areas of different tissues. However, the cerebrovascular diseases may result in a delayed and dispersed local perfusion and therefore alter the hemodynamic signal profiles. Assessing the accuracy of the segmentation technique under delayed/dispersed circumstance is critical to accurately evaluate the severity of the vascular disease. In this study, we improved the segmentation method of expectation-maximization algorithm by using the results of hierarchical clustering on whitened perfusion data as initial parameters for a mixture of multivariate Gaussians model. In addition, Monte Carlo simulations were conducted to evaluate the performance of proposed method under different levels of delay, dispersion, and noise of signal profiles in tissue segmentation. The proposed method was used to classify brain tissue types using perfusion data from five normal participants, a patient with unilateral stenosis of the internal carotid artery, and a patient with moyamoya disease. Our results showed that the normal, delayed or dispersed hemodynamics can be well differentiated for patients, and therefore the local arterial input function for impaired tissues can be recognized to minimize the error when estimating the cerebral blood flow. Furthermore, the tissue in the risk of infarct and the tissue with or without the complementary blood supply from the communicating arteries can be identified.

Reverse waffle cone technique in management of stent dislodgement into intracranial aneurysms

Stent-assisted coil embolization (SACE) is a common method to manage intracranial wide-neck aneurysm. Using this technique, a stent must be successfully deployed into the parent artery to cross the aneurysm neck. We describe the reverse waffle cone technique in management of intra-procedural stent dislodgement during SACE of internal carotid artery (ICA) wide-neck aneurysms. Two patients with unruptured wide-neck ICA aneurysms underwent SACE. Intra-procedural forward stent migration occurred during catheterization with proximal stent dislodgement and migration into the aneurysm sac. Navigation of a second stent to bridge the aneurysm neck failed in one patient because the second stent was impeded by the dislodged stent. Using the reverse waffle cone technique, a microcatheter was navigated into the aneurysm sacs. Coils were safely detached into each aneurysm sac without any device assistance. The two wide-neck aneurysms were successfully treated with preservation of flow to the internal carotid arteries. The complication of intra-procedural distal stent migration and dislodgement, with proximal stent prolapse into an aneurysm sac, may not result in a failure to coil the aneurysm. The reverse waffle cone technique provides an effective treatment in the management of this complication.

Unusual giant intraspinal teratoma in an infant

There are few cases of giant pediatric intraspinal teratoma. We report a case of a 4-month-old female baby with giant intraspinal teratoma. Magnetic resonance imaging (MRI) of the spine revealed a large intradural tumor from the C7 to S2 level, with solid, cystic, and fatty components. Partial surgical removal of the tumor showed pathology of a mature cystic teratoma. The imaging diagnosis of intraspinal teratoma included the location, solid and cystic component, and fatty content. The MR techniques adopted included gradient echo sequences as used to detect teeth or calcification. The difficulties in surgical resection of this case are also presented.

Isotropic three-dimensional MRI-Fricke-infused gel dosimetry

PURPOSE

Fricke-infused gel has been shown to be a simple and attainable method for the conformal measurement of absorbed radiation dose. Nevertheless, its accuracy is seriously hindered by the irreversible ferric ion diffusion during magnetic resonance imaging, particularly when three-dimensional (3D) dose measurement in radiosurgery is considered. In this study, the authors developed a fast three-dimensional spin-echo based Fricke gel dosimetry technique to reduce the adverse effects of ferric ion diffusion and to obtain an accurate isotropic 3D dose measurement.

METHODS

A skull shaped phantom containing Fricke-infused gel was irradiated using Leksell Gamma Knife. The rapid image-based dosimetry technique was applied with the use of a 3D fast spin-echo magnetic resonance imaging sequence. The authors mathematically derived and experimentally validated the correlations between dose-response characteristics and parameters of the 3D fast spin-echo MR imaging sequence. Absorbed dose profiles were assessed and compared to the calculated profiles given by the Gamma Knife treatment planning system. Coefficient of variance (CV%) and coefficient of determination (R(2)) were used to evaluate the precision of dose-response curve estimation. The agreement between the measured and the planned 3D dose distributions was quantified by gamma-index analysis of two acceptance criteria.

RESULTS

Proper magnetic resonance imaging parameters were explored to render an accurate three-dimensional absorbed dose mapping with a 1 mm(3) isotropic image resolution. The efficacy of the dose-response estimation was approved by an R(2) > 0.99 and an average CV% of 1.6%. Average gamma pass-rate between the experimentally measured and GammaPlan calculated dose distributions were 83.8% and 99.7% for 2%/2 and 3%/3 mm criteria, respectively.

CONCLUSIONS

With the designed MR imaging sequence and parameters, total 3D MR acquisition time was confined to within 20 min postirradiation, during which time ferric ion diffusion effects were negligible, thus enabling an accurate 3D radiation dose measurement.

Fistula components of brain arteriovenous malformations: angioarchitecture analysis and embolization prior to gamma-knife surgery

BACKGROUND

Gamma-knife surgery (GKS) is ineffective for high-flow arteriovenous fistula (AVF). The purpose of this study was to present the angioarchitecture of the AVF of brain arteriovenous malformation (BAVM) and report our experience of endovascular embolization of AVF component prior to GKS.

METHODS

In the past 10 years, a total of 523 BAVMs had been treated primarily by GKS. Among these, 10 patients with AVF components were identified and referred for embolization prior to GKS. Those patients underwent GKS within 4 weeks after embolization. We analyzed retrospectively the angioarchitecture of the AVFs of BAVMs, selection of embolic materials for embolization, and treatment outcomes.

RESULTS

The location of the AVFs was anterior (n = 7) or middle (n = 3) cerebral artery. Central and peripheral types of AVFs were found in seven and three patients, respectively. Nine AVFs were totally occluded by a single session of endovascular embolization, while one failed to be embolized because it was inaccessible to a microcatheter. Detachable coils (n = 6) or combination of liquid adhesives (n = 3) were selected to embolize the AVF. No significant periprocedural neurological complication was found. BAVMs were obliterated totally by subsequent GKS in six patients and partial occlusion was achieved in one, while three still awaited the effect of GKS. Mean imaging and clinical follow-up periods were 35 and 48 months, respectively.

CONCLUSION

Early detection of the central type of AVF of BAVM prior to GKS may be difficult because of its overlapping with feeder, nidus, and/or venous drains or it being overlooked. Peripheral-type AVFs were usually evident prior to GKS, particularly those with proximal dilated venous drains. Endovascular embolization is an effective modality for managing these AVFs, which may be treated by GKS ineffectively.

Can iterative reconstruction improve imaging quality for lower radiation CT perfusion? Initial experience

BACKGROUND AND PURPOSE

Initial results using IR for CT of the head showed satisfactory subjective and objective imaging quality with a 20-40% radiation dose reduction. The aim of our study was to compare the influence of IR and FBP algorithms on perfusion parameters at standard and lowered doses of CTP.

MATERIALS AND METHODS

Forty patients with unilateral carotid stenosis post-carotid stent placement referred for follow-up CTP were divided into 2 groups (tube currents were 100 mAs in group A and 80 mAs in group B). Datasets were reconstructed with IR and FBP algorithms; and SNRs of gray matter, white matter, and arterial and venous ROIs were compared. CBF, CBV, and MTT means and SNRs were evaluated by using linear regression, and qualitative imaging scores were compared across the 2 algorithms.

RESULTS

The mean effective radiation dose of group B (2.06 mSv) was approximately 20% lower than that of group A (2.56 mSv). SNRs for ROIs in the dynamic contrast-enhanced images were significantly higher than those for the FBP images. Correlations of the SNRs for CBF, CBV, and MTT across the 2 algorithms were moderate (R² = 0.46, 0.23, and 0.44, respectively). ROIs in gray matter rather than the IR algorithm predicted increasing SNRs in all CBF, CBV, and MTT maps. Two cases of significant restenosis were confirmed in both algorithms. CBV, CBF, and MTT imaging scores did not differ significantly across algorithms or groups.

CONCLUSIONS

Lower dose CTP (20% below normal dose) without IR can effectively identify oligemic tissue in poststenting follow-up. IR does not alter the absolute values or increase the SNRs of perfusion parameters. Other methods should be attempted to improve SNRs in settings with low tube currents.

Application of color-coded digital subtraction angiography in treatment of indirect carotid-cavernous fistulas: initial experience

BACKGROUND

Parametric-colored digital subtraction angiography using Tmax is almost a routine angiographic imaging procedure, currently. The current feasibility study is aimed to using the imaging to monitor treatment effects while embolizing indirect carotid-cavernous fistulas (CCF).

METHODS

Ten patients with CCFs receiving embolization and 40 patients with normal circulation time were recruited. Their color-coded DSAs were used to define the Tmax of selected intravascular ROIs. A total of 19 ROIs in the internal carotid artery (ICA) (cervical segment of ICA in AP view (I0), cavernous segment of ICA in AP view (I1), supraclinoid segment of ICA in AP view (I2) and cervical segment of ICA in lateral view (I0'), cavernous portion of ICA in lateral view (IA), supraclinoid portion of ICA in lateral view (IB)), ACA (first segment of anterior cerebral artery, second segment of anterior cerebral artery (A1, A2)), middle cerebral vein (MCA) first segment of MCA ((M1), second segment of MCA (M2)), frontal vein (FV), parietal vein (PV), superior sagittal sinus (SSS), sigmoid sinus (SS), internal jugular vein (JV), fistula, superior ophthalmic vein (SOV), inferior petrosal vein (IPS), and MCV were selected. Relative Tmax was defined as the Tmax at selected ROIs minus Tmax at I0 or I0'. An intergroup comparison between the normal and treatment groups and pre- and post-treatment comparison of the peri-therapeutic rTmax for the treatment group were performed.

RESULTS

rTmax's for the normal group were as follows: Anterior-posterior view: I1: 0.16, I2: 0.32, A1: 0.31, M1: 0.35, SSS: 6.16, SS: 6.56, and MCV: 3.86 seconds. Lateral view: IA: 0.05, IB: 0.20, A2: 0.53, M2: 0.95, FV: 4.84, PV: 5.12, IPS: 4.62, JV: 6.81, and MCV: 3.86 seconds. Before embolization, rTmax of the IPS, SS, and JV for the treatment group were shortened (p < 0.05). No rTmaxs for any arterial ROIs in the fistula group were significantly different. After embolization, the rTmaxs for all venous ROIs returned to normal except for two which were partially obliterated.

CONCLUSION

This postprocessing method does not require extra radiation exposure and contrast media. It facilitates real-time hemodyamic monitoring and may help determining the endpoint of embolization, which increases patient safety.

Gamma Knife surgery for central neurocytomas

OBJECT

The optimal management of central neurocytoma (CN) remnants and recurrences is still not clear. To date no large series of patients treated with Gamma Knife surgery (GKS) for CNs has been published. For that reason the authors decided to combine data from 5 different centers so that they could analyze the largest population of patients treated with GKS for CN currently available.

METHODS

Data obtained in 42 patients who were treated for CN with GKS before July 1, 2010, were retrospectively collected and analyzed. The median prescribed dose was 13 Gy (range 11-25 Gy). The follow-up time in these patients ranged from 0.5 to 14.7 years (mean 6.1 years, median 4.9 years). Eleven patients were followed up for 5-10 years and 9 patients for more than 10 years. All patients were alive and well at the closing of the study except 1 patient, who died of injuries sustained in a traffic accident.

RESULTS

Two cases of local tumor progression and 2 cases of distant tumor recurrence occurred among the patient population, yielding 5- and 10-year tumor control rates of 91% and 81%, respectively. No permanent complications occurred. The findings were in line with results reported in earlier publications. Despite the high tumor control rate, enlargement of part of or the whole ventricular system was seen in 45% of patients.

CONCLUSIONS

The high tumor control rate and the low complication rate following GKS indicate that GKS is the preferred treatment for CN tumor remnants or recurrences following microsurgery. However, data from longer follow-up times in more patients are needed before this conclusion can be validated. The patients need to be closely monitored and potential hydrocephalus managed despite tumor control.

Brainstem cavernous malformations: the role of Gamma Knife surgery

OBJECT

The authors retrospectively reviewed the efficacy and safety of Gamma Knife surgery (GKS) in patients with brainstem cavernous malformations (CMs). The CMs had bled repeatedly and placed the patients at high risk with respect to surgical intervention.

METHODS

Between 1993 and 2010, 49 patients with symptomatic CMs were treated by GKS. The mean age in these patients was 37.8 years, and the predominant sex was female (59.2%). All 49 patients experienced at least 2 instances of repeated bleeding before GKS; these hemorrhages caused neurological deficits including cranial nerve deficits, hemiparesis, hemisensory deficits, spasticity, chorea or athetosis, and consciousness disturbance.

RESULTS

The mean size of the CMs at the time of GKS was 3.2 cm(3) (range 0.1-14.6 cm(3)). The mean radiation dose directed to the lesion was 11 Gy with an isodose level at 60.0%. The mean clinical and imaging follow-up time was 40.6 months (range 1.0-150.7 months). Forty-five patients participated in regularly scheduled follow-up. Twenty-nine patients (59.2%) were followed up for > 2 years, and 16 (32.7%) were followed up for < 2 years. The pre-GKS annual hemorrhage rate was 31.3% (69 symptomatic hemorrhages during a total of 220.3 patient-years). After GKS, 3 episodes of symptomatic hemorrhage were observed within the first 2 years of follow-up (4.29% [corrected] annual hemorrhage rate), and 3 episodes of symptomatic hemorrhage were observed after the first 2 years of follow-up (3.64% [corrected] annual hemorrhage rate). In this study of 49 patients, symptomatic radiation-induced complications developed in only 2 patients (4.1%; cyst formation in 1 patient and perifocal edema with neurological deficits in the other patient). There were no deaths in this group.

CONCLUSIONS

Gamma Knife surgery is effective in reducing the rate of recurrent hemorrhage. In the authors' experience, it was possible to control bleeding using a low-dose treatment. In addition, there were few symptomatic radiation-induced complications. As a result, the authors believe that GKS is a good alternative treatment for brainstem CMs.

Quantitative flow measurement by digital subtraction angiography in cerebral carotid stenosis using optical flow method

OBJECTIVE

We analyzed intracranial regional blood flows using an optical flow method (OFM) and digital subtraction angiography in patients with internal carotid artery (ICA) stenosis. We also retrospectively explored the correlation between the patients' diagnoses and the severity of the ICA stenoses.

MATERIALS AND METHODS

OFM, an image-processing algorithm to estimate motion, was applied to determine the mean velocity V(mean) in the vessels. A group of 40 patients without vascular anomalies acted as the control group. The patients were classified as having either moderate stenosis (< 80%, n=14) or severe stenosis (> 80%, n=23).

RESULTS

The V(mean) of the ICAs was significantly lower in the stenotic group compared with the control group (p< 0.01). The V(mean) of the ICAs was inversely correlated with the severity of the stenosis (p< 0.05). The receiver operating characteristic curve of the V(mean) in an AP view showed substantial discriminatory power, with an optimal cutoff value of 3.48 pixels/frame for the detection of patients with carotid stenosis. The sensitivity and specificity were 84% and 50%, respectively. On a lateral view, the best cutoff for the V(mean) was 4.01 pixels/frame, and the sensitivity and specificity were 92% and 43%, respectively.

CONCLUSIONS

Digital subtraction angiography combined with the OFM is a feasible parametric method for intracranial blood flow measurements in patients with moderate to severe carotid stenosis.

Transarterial detachable coil embolization of direct carotid-cavernous fistula: immediate and long-term outcomes

BACKGROUND

Transarterial embolization is a standard method for management of direct carotid-cavernous fistula (DCCF). The purpose of this study was to report our experiences, and immediate and long-term outcomes of endovascular embolization of DCCFs by using detachable coils (DCs).

METHODS

Over 8 years, 24 patients with 25 DCCFs underwent endovascular DC embolization. There were 15 men and nine women; age ranged from 8 to 82 years (mean, 39 years). Immediate and long-term angiographic as well as clinical outcomes after endovascular DC embolization were retrospectively analyzed. The number and the length of DCs used to occlude the fistula were also evaluated.

RESULTS

Eighteen DCCFs were successfully occluded by single-session endovascular embolization with preservation of the parent artery. Retreatments by transvenous (n = 5) and/ or transorbital routes (n = 3) had to be performed in seven patients because of residual fistula (n = 4) or recurrent fistula (n = 4) occurring within 3 weeks after embolization. The average numbers and length of coils to occlude the fistulas were 14 (range, 2-31) and 189 cm (range, 16-756 cm), respectively. Four patients had small residual fistulas with spontaneous thrombosis on follow-up angiography. Three patients had transient cranial nerve impairment of the third (n = 1) or sixth (n = 2) nerve. There was no significant procedure-related neurological complication. The follow-up period was 3-48 months (mean, 19 months)

CONCLUSION

Endovascular DC embolization of DCCFs was proved both efficacious and safe in managing high-flow fistulas with sustained angiographic and clinical effects, particularly in those DCCFs with small fistula track and/or cavernous sinus. However, retreatment via various routes may be necessary in some patients because of residual or recurrent fistulas.