Contrast Enhancement Reduction Research Articles

IMG-24. MAPK-ALTERED PEDIATRIC LOW-GRADE GLIOMA: MRI HINTS TO EXPLAIN THE INTERPLAY BETWEEN GLIOMA AND IMMUNE CELLS

Abstract BACKGROUND In MAPK-altered pediatric low-grade glioma (pLGG), immune infiltration may be involved in treatment response. It is debated whether tumor immune cell infiltration is due to expansion of endogenous resident microglia or to the active recruitment of bone marrow-derived microglial progenitors from the bloodstream. This study aimed to investigate the relation between neuroradiological features of MAPK-altered pLGG and treatment response to MAPK-inhibitors (MAPKi). METHODS We conducted a retrospective analysis of all patients with unresectable BRAF-V600E mutated brain pLGG, radiotherapy naïve, treated with MAPKi at our institution since 2015. MRI studies were reviewed by two experienced neuroradiologist and tumor response assessed according to RAPNO criteria. RESULTS 12 patients were enrolled (9 female). Median age at treatment start was 6.2 years (range 2.7–14.3 years). Four were pilocytic astrocytomas, 6 gangliogliomas, and 2 desmoplastic infantile gangliogliomas. Five patients received MAPKi as first line, 7 following other chemotherapy lines. Median follow-up was 4.1 years (range 2.5–8.7 years). Tumor response was associated with contrast enhancement (CE): 9 out of 10 patients with CE at treatment onset had at least partial response and subsequent CE resolution, while both 2 out of 2 patients without CE showed stable disease. A 4-year old contrast enhancing-ganglioglioma who reached partial response and CE resolution with MAPKi, presented disease progression four days after treatment withdrawal; treatment re-start determined tumor and CE reduction after only 7 days. CONCLUSIONS We hypothesize that brain-blood barrier breakage is induced by tumor infiltration of bloodstream immune cells, and that this trafficking is stimulated by tumor cell secreted products and determined by microglial progenitors shift from the bloodstream to the tumor site. MAPKi treatment may incite blood-brain barrier reconstitution as it reduces the trafficking between tumor site and bloodstream. ACKNOWLEDGEMENT This work was supported by grant number NET-2018-12366666 NeuroArtP3 from the Italian Ministry of Health.

CT Urology에서 가돌리늄 조영제 제거를 위한 이중에너지 CT의 Virtual Non-Contrast 기술의 평가

Residual gadolinium contrast agents in the urinary tract following MRI contrast-enhanced examinations often presents as elevated Hounsfield Unit (HU) values on CT scans, impeding the efficacy of CT urology procedures. This study aims to explore the feasibility of addressing this challenge through the application of the Dual-Energy Computed Tomography (DECT) Virtual Non-Contrast (VNC) technique across various energy levels. HU values of residual gadolinium contrast agent in the renal pelvis and ureter were measured in patients who underwent MRI contrast-enhanced examinations followed by non-contrast CT chest examinations. Subsequently, gadolinium contrast agent mixtures, such as Max, Mean, and Min Mixtures, were created and scanned together with normal saline using DECT at various energy levels. Additionally, an iodine mixture and a virtual stone representing urolithiasis were fabricated and evaluated. The results demonstrated a significant reduction in contrast enhancement of gadolinium contrast agent with DECT VNC at 70 kV and Sn150 kV. The Min Mixture closely resembled normal saline in both HU and Contrast-to-Noise Ratio (CNR), facilitating the differentiation between iodine contrast agent and virtual urolithiasis. Therefore, utilizing DECT VNC after a 1-hour and 30-minute interval following MRI contrast-enhanced examinations effectively eliminates gadolinium contrast agents, improving the efficacy of CT Urology imaging procedures.

Liquid biopsy guides successful molecular targeted therapy of an inoperable pediatric brainstem neoplasm

Midline CNS tumors are occasionally inaccessible for surgical biopsies. In these instances, cell-free DNA (cfDNA) may serve as a viable alternative for molecular analysis and identification of targetable mutations. Here, we report a young child with an inoperable brainstem tumor in whom a stereotactic biopsy was deemed unsafe. The tumor progressed on steroids and after radiotherapy the patient developed hydrocephalus and received a ventriculoperitoneal shunt. Droplet digital PCR analysis of cfDNA from an intraoperative cerebrospinal fluid liquid biopsy revealed a BRAF V600 mutation enabling targeted treatment with MEK and BRAF inhibitors. The patient, now on trametinib and dabrafenib for 1 year, has had substantial tumor volume regression and reduction of contrast enhancement on MRIs and is making remarkable clinical progress. This case highlights that in a subset of CNS tumors, access to liquid biopsy analysis may be crucial to identify actionable therapeutic targets that would otherwise go undiscovered.

Early radiological response evaluation with response evaluation criteria in solid tumors 1.1 stratifies survival in hepatocellular carcinoma patients treated with lenvatinib.

Background and AimLenvatinib (LEN) has an antitumor effect with an early reduction in contrast enhancement for unresectable hepatocellular carcinoma (HCC). The aim of this study was to reveal the most useful radiological response evaluation for overall survival (OS) in patients treated with LEN.MethodsPatients receiving LEN therapy (n = 80) were retrospectively recruited from April 2018 to January 2020. Enhanced computed tomography scans were performed at baseline and every 4–8 weeks. OS and radiological response were evaluated using response evaluation criteria in solid tumors (RECIST 1.1), modified RECIST (mRECIST), and Choi criteria. To be eligible for study, a minimal cumulative duration of LEN was 4 weeks. A total of 62 patients were included in the analysis.ResultsThe median OS was 469 days. The RECIST 1.1, mRECIST, and Choi criteria identified 14 (22.5%), 30 (48.3%), and 33 (53.2%) patients with an objective response, respectively. In the univariate analysis, Child–Pugh class B, major vascular invasion, and high alpha‐fetoprotein (>200) were statistically significant poor prognostic factors. Radiological response was a significantly better prognostic factor in each criterion (RECIST, mRECIST, and Choi). In the multivariate analysis, radiological response evaluated by RECIST (hazard ratio, 0.259; 95% confidence interval, 0.0723–0.928; P = 0.038) was an independent factor. Furthermore, only RECIST significantly stratified prognosis (P = 0.041) when limited to the first evaluation.ConclusionRECIST 1.1 was useful even as early therapeutic evaluation for HCC patients treated with LEN. Understanding the characteristics of radiological response over time may contribute to improving the prognosis of patients with HCC.

Synthesis, Characterization, and Application of Superparamagnetic Iron Oxide Nanoprobes for Extrapulmonary Tuberculosis Detection

A molecular imaging probe comprising superparamagnetic iron oxide (SPIO) nanoparticles and Mycobacterium tuberculosis surface antibody (MtbsAb) was synthesized to enhance imaging sensitivity for extrapulmonary tuberculosis (ETB). An SPIO nanoprobe was synthesized and conjugated with MtbsAb. The purified SPIO-MtbsAb nanoprobe was characterized using TEM and NMR. To determine the targeting ability of the probe, SPIO-MtbsAb nanoprobes were incubated with Mtb for in vitro imaging assays and injected into Mtb-inoculated mice for in vivo investigation with magnetic resonance (MR). The contrast enhancement reduction on magnetic resonance imaging (MRI) of Mtb and THP1 cells showed proportional to the SPIO-MtbsAb nanoprobe concentration. After 30 min of intravenous SPIO-MtbsAb nanoprobe injection into Mtb-infected mice, the signal intensity of the granulomatous site was enhanced by 14-fold in the T2-weighted MR images compared with that in mice receiving PBS injection. The MtbsAb nanoprobes can be used as a novel modality for ETB detection.

Regorafenib CSF Penetration, Efficacy, and MRI Patterns in Recurrent Malignant Glioma Patients.

(1) Background: The phase 2 Regorafenib in Relapsed Glioblastoma (REGOMA) trial indicated a survival benefit for patients with first recurrence of a glioblastoma when treated with the multikinase inhibitor regorafenib (REG) instead of lomustine. The aim of this retrospective study was to investigate REG penetration to cerebrospinal fluid (CSF), treatment efficacy, and effects on magnetic resonance imaging (MRI) in patients with recurrent high-grade gliomas. (2) Methods: Patients were characterized by histology, adverse events, steroid treatment, overall survival (OS), and MRI growth pattern. REG and its two active metabolites were quantified by liquid chromatography/tandem mass spectrometry in patients’ serum and CSF. (3) Results: 21 patients mainly with IDH-wildtype glioblastomas who had been treated with REG were retrospectively identified. Thirteen CFS samples collected from 3 patients of the cohort were available for pharmacokinetic testing. CSF levels of REG and its metabolites were significantly lower than in serum. Follow-up MRI was available in 19 patients and showed progressive disease (PD) in all but 2 patients. Two distinct MRI patterns were identified: 7 patients showed classic PD with progression of contrast enhancing lesions, whereas 11 patients showed a T2-dominant MRI pattern characterized by a marked reduction of contrast enhancement. Median OS was significantly better in patients with a T2-dominant growth pattern (10 vs. 27 weeks respectively, p = 0.003). Diffusion restrictions were observed in 13 patients. (4) Conclusion: REG and its metabolites were detectable in CSF. A distinct MRI pattern that might be associated with an improved OS was observed in half of the patient cohort. Treatment response in the total cohort was poor.

Comparison of contrast-enhanced digital mammography and contrast-enhanced digital breast tomosynthesis for lesion assessment.

Contrast-enhanced digital mammography (CEDM) reveals neovasculature of breast lesions in a two-dimensional contrast enhancement map. Contrast-enhanced digital breast tomosynthesis (CEDBT) provides contrast enhancement in three dimensions, which may improve lesion characterization and localization. We aim to compare CEDM and CEDBT for lesion assessment. Women with breast imaging-reporting and data system 4 or 5 suspicious breast lesion(s) were recruited in our study and were imaged with CEDM and CEDBT in succession under one breast compression. Two radiologists assessed CEDM and CEDBT with both images displayed side-by-side and compared (1)contrast enhancement of lesions and (2)lesion margin using a five-point scale ranging from (CEDM much better) to (CEDBT much better). Biopsy identified 19 malignant lesions with contrast enhancement. Our results show that CEDBT provides better lesion margins than CEDM with limited reduction in contrast enhancement. CEDBT delivers less radiation dose compared to CEDM + DBT. Synthetic CEDM can be generated from CEDBT data and provides lesion contrast enhancement comparable to CEDM. CEDBT has potential for clinical applications, such as treatment response monitoring and guidance for biopsy.

The usefulness of fibrin glue as a support in the dissection of malignant cystic brain tumors

BackgroundIf the complete microsurgical resection of a brain tumor is a logical oncologic goal, the surgical strategy for the cystic component remains controversial secondary to the risk of morbidity. The objective of this study was to analyze the interest of using fibrin glue in the resection of malignant cystic brain tumors (MCBT). MethodsSeven patients (median: 60-years-old (range [52–72]/sex ratio M/F: 2.5) were analyzed prospectively in the Neurosurgery Department at Strasbourg University Hospital, from October 2014 to November 2016. The surgical technique consisted of injecting fibrin glue into the tumor cyst after partial drainage. After the solidification of the glue, the cysts walls were removal by following the dissection plan around the fibrin glue. The primary objective was to evaluate the quality of surgical resection on brain MRI scans postoperatively with the use of ITK-SNAP software for precise measurements of tumor volume. ResultsFour metastases and 3 glial lesions were operated on with this technique. An average reduction in cystic volume of 64.6% (P=0.016) and 82.1% (P=0.016) for contrast enhancement volume were observed. If two cases (#2 and #7) were excluded, the average contrast enhancement reduction was respectively 94% and 72% for the cystic volume. In addition, there were no complications, tumor recurrence or difference between gliomas and metastases and the Karnofsky score increased by at least 10% in all patients. ConclusionThis procedure allowed to extend the resection to the cystic component of MCBT without increasing the risk of morbidity related to injury on the underlying parenchyma.

Lack of functional normalisation of tumour vessels following anti-angiogenic therapy in glioblastoma

Neo-angiogenesis represents an important factor for the delivery of oxygen and nutrients to a growing tumour, and is considered to be one of the main pathodiagnostic features of glioblastomas (GBM). Anti-angiogenic therapy by vascular endothelial growth factor (VEGF) blocking agents has been shown to lead to morphological vascular normalisation resulting in a reduction of contrast enhancement as seen by magnetic resonance imaging (MRI). Yet the functional consequences of this normalisation and its potential for improved delivery of cytotoxic agents to the tumour are not known. The presented study aimed at determining the early physiologic changes following bevacizumab treatment. A time series of perfusion MRI and hypoxia positron emission tomography (PET) scans were acquired during the first week of treatment, in two human GBM xenograft models treated with either high or low doses of bevacizumab. We show that vascular morphology was normalised over the time period investigated, but vascular function was not improved, resulting in poor tumoural blood flow and increased hypoxia.

The impact of contrast enhancement reduction on tumor response in patients with advanced renal cell carcinoma that treated with presurgical targeting therapy.

510 Background: RECIST is a standard tool for tumor response assessment. However, evaluation for targeted therapy by RECIST is insensitive because tumors often showed a modest change in size despite of significant necrosis. Therefore, we investigated an impact of contrast enhancement reduction for tumor shrinkage in RCC patients with presurgical targeting therapy. Methods: From March 2011 to July 2015, 17 patients (18 tumors) with RCC who underwent presurgical targeting therapy were included. Indications for presurgical targeting therapy were cT3-4, bilateral tumors, poor performance status, or small distant metastasis. Contrast enhancement reduction was evaluated by contrast medium enhanced area (CMEA) before and after targeting therapy. CMEA measurements were performed by OsiriX and Adobe Photoshop. Eighteen tumors were evaluated by RECIST and CMEA. Differences between two methods were compared. Results: Median age and followup after initiation of targeted therapy were 68 years old and 15.3 months. IVC thrombus and small distant metastasis existed in seven (41%) and five (29%) patents, respectively. Fifteen patients (88%) received TKI based (sunitinib and/or axitinib), and three patients (12%) received mTOR inhibitor based (everolimus or temsirolimus) presurgical therapy. The median treatment period of presurgical targeted therapy was 3.3 months. Median tumor responses in RECIST and CMEA were 10.5% and 49.0%, that was significantly correlated by liner regression analysis (P = 0.002). TKI based presurgical therapy showed significant tumor reduction in CMEA than RECIST (P = 0.0062). In addition, tumor reduction rate was significantly higher in TKI based presurgical therapy than mTOR inhibitor (P = 0.014). No patient experienced tumor recurrence. Conclusions: Contrast enhancement reduction might be useful tool for tumor shrinkage in patients with RCC who underwent presurgical targeting therapy.

ROBOTIC RADIOTHERAPY IS IN THE TREATMENT OF PATIENTS WITH ONCOUROLOGICAL PATHOLOGY

The authors Analyzed the immediate and remote results of treatment of patients with prostate cancer treated by the method - a robotic radiotherapy. Immediate results of treatment were estimated on the level of total PSA, prostate volume, residual urine, change according to the international scale IPSS. The dynamics of the above indicators showed regression of the primary lesion, and the absence of pronounced radiation reactions affect the quality of life of patients. We analyzed the results of overall, relapse-free survival and oncospecific. Three-year disease-free survival in patients receiving radiation therapy is of 88.8%. Overall survival, as well as oncospecific survival rate is 100%. Also presents first experience of using stereotactic radiotherapy in patients of renal cell carcinoma. Treatment received two (one patient carried out the irradiation of both kidneys). In one patient, complete tumor resorption of the right kidney and a decrease in the size and reduction of contrast enhancement of the tumor of the left kidney. Renal function did not deteriorate. The second patient decreased the size of the tumor, but preserved the contrast enhancement in the vascular phase. The only function of the kidney has not deteriorated.

Teaching Neuro Images : Basal ganglia involvement in facio-brachial dystonic seizures associated with LGI1 antibodies

A 30-year-old man developed right faciobrachial dystonic seizures (FBDS).1 Ictal and interictal EEGs were normal. CSF analysis was unremarkable. Brain MRI revealed a gadolinium-enhancing lesion involving the left caudate and globus pallidus (figure 1). Leucine-rich glioma inactivated protein 1 (LGI1) antibodies were detected in the serum. Total-body CT scan revealed no malignancies. The patient underwent 5 cycles of plasmapheresis followed by long-term steroid therapy with complete benefit. A brain MRI performed after 5 months showed reduction of contrast enhancement (figure 2). LGI1, a secreted protein complexed with voltage-gated potassium channels, is highly expressed in the neocortex and hippocampus.2 LGI1 mutations have been described in patients with autosomal dominant partial epilepsy with auditory features (ADPEAF). Our patient had no clinical features of ADPEAF. Whether FBDS can be classified as epilepsy or dystonia is a matter of debate.3 The involvement of basal ganglia described in our patient can be relevant to the ongoing debate.

Super-paramagnetic iron oxide nanoparticles for use in extrapulmonary tuberculosis diagnosis

The limited sensitivity of serological tests for mycobacterial antigens has encouraged the development of a nanoparticle probe specific for the extrapulmonary form of Mycobacterium tuberculosis (Mtb). We developed an innovative probe comprised of super-paramagnetic iron oxide (SPIO) nanoparticles conjugated with Mtb surface antibody (MtbsAb-nanoparticles) to provide ultrasensitive imaging of biomarkers involved in extrapulmonary Mtb infection. MtbsAb-nanoparticles were significantly conjugated with Mtb bacilli. The extent of contrast enhancement reduction on magnetic resonance imaging (MRI) for Mtb and human monocytic THP1 cells was proportional to the concentration of MtbsAb-nanoparticles. When MtbsAb-nanoparticles were intravenously injected into mice bearing Mtb granulomas, the granulomatous site showed a 14-fold greater reduction in signal intensity enhancement on T2-weighted MR images compared with an opposing site that received PBS injection. Mtb sAb-nanoparticles represent a new non-invasive technology for the diagnosis of extrapulmonary Mtb.

Glioblastoma Presenting with Steroid-Induced Pseudoregression of Contrast Enhancement on Magnetic Resonance Imaging

Corticosteroid-induced reduction in contrast enhancement on radiographic imaging is most commonly associated with lymphoma but has been reported in other entities, including glioma. This finding may represent a diagnostic dilemma. Concern that steroid-induced cytotoxicity obscures histological diagnosis of suspected lymphoma may lead to postponement of a biopsy. If glioma is not considered in the differential diagnosis, reduction in tumor contrast enhancement may be misinterpreted as disease regression rather than a transient radiographic change. We report a case of a patient with an enhancing right temporoparietal mass adjacent to the atrium of the lateral ventricle. After treatment with dexamethasone was started, the mass exhibited marked reduction in contrast enhancement, with symptom improvement. The clinical course suggested lymphoma, and surgery was not performed. Subsequent screening for extra-axial lymphoma was negative. Two weeks later, the patient developed worsening symptoms, and repeat T1-weighted imaging showed interval increase in size and enhancement. The findings suggested a possible diagnosis of malignant glioma. The patient underwent a stereotactic-guided craniotomy for excision of the right temporoparietal mass lesion. Final histological diagnosis was glioblastoma multiforme, World Health Organization grade IV.

CT response assessment combining reduction in size and arterial enhancement correlates with time to progression in metastatic renal cancer patients treated with TKIs

e16062 Background: Targeted therapy is now the standard of care in advanced Renal Carcinoma (RCC). Response assessment by RECIST criteria is insensitive as treated tumours often have only a modest change in size despite the induction of significant necrosis and does not correlate with time to progression (TTP). The Choi criteria (10% size reduction or 15% contrast enhancement reduction) are routinely used in the assessment of GIST tumours treated with targeted agents. We report the use of combined size and density assessment in RCC metastases treated with either sunitinib or cediranib. Methods: CT scans from 32 patients with metastatic RCC treated with either sunitinib (18) or cediranib (14) were assessed. Scans from 10 patients were not evaluable as non-contrast enhanced scans were performed due to impaired renal function. Scans from a further 2 patients were excluded as they ceased treatment due to toxicity rather than progression. Scans from 20 evaluable patients at baseline and 12 weeks on treatment were assessed using RECIST, Choi, and modified criteria in which both a 10% decrease in size and 15% decrease in enhancement in the arterial phase were required to define a response (PR). A total of 60 lesions were assessed. Response assessment was performed using each of the three methods and correlated with time to disease progression (itself RECIST defined). Statistical analysis was performed using the Mann-Whitney U test. Results: There was no difference in TTP between RECIST defined PR (346.8 days) and SD (328.5 days) (P=0.965). TTP in Choi defined PR (358.4 days) and SD (189.6 days) groups showed improved but non-significant separation of TTP duration (P=0.266). TTP in PR (421.5 days) and SD (200.3 days) groups defined by a combined assessment of reduction in size and enhancement showed greatly improved separation (P=0.064). Conclusions: A combined reduction in both size and arterial phase enhancement of RCC metastases treated with TKIs correlates with time to progression. RECIST and standard Choi criteria appear inferior. No significant financial relationships to disclose.

Abstract 2941: Combined Assessment of Coronary Artery Stenosis and Myocardial Ischemia by Rest-Dipyridamole Stress Multidetector Computed Tomography

Introduction: MDCT coronary angiography has been evolving as a noninvasive method for the assessment of coronary artery disease (CAD). More recently, It has been demonstrated that MDCT identifies reduced contrast enhancement in ischemic and/or scarred myocardial segments. Objective: to determine the ability of rest-stress multidetector computed tomography (RS-MDCT) to detect myocardial ischemia and to assess the relationship between MDCT myocardial perfusion abnormalities and coronary artery stenosis. Methods: Forty seven patients underwent stress/rest 99mTc sestamibi SPECT and RS-MDCT, using a 16-row detector scanner (Philips Brilliance-16). Myocardial segments were classified by SPECT as normal, ischemic or scarred. SPECT results were then compared with MDCT regional myocardial contrast enhancement. The results of MDCT coronary angiography were also analyzed in 20 patients who underwent invasive catheterization. Results: The presence of a reduction in contrast enhancement at rest by MDCT identified scar by SPECT with 96% sensitivity and 98% specificity. A stress-induced reduction in contrast enhancement by MDCT identified ischemia by SPECT with 77% sensitivity and 99% specificity. The segment-based sensitivity and specificity for the detection of significant stenosis by MDCT were 92% and 98%, respectively. Conclusion: Our results showed that a rest-dipyridamole stress MDCT protocol can identify the presence of myocardial ischemia as well as the severity of coronary artery stenosis in patients with suspected coronary artery disease.

Evaluation of neoadjuvant chemotherapeutic response of breast cancer using dynamic MRI with high temporal resolution.

The aim of this study was to evaluate changes in both size and contrast enhancement of breast tumors during neoadjuvant chemotherapy, using dynamic MRI with high temporal resolution. Patients with advanced breast cancer (n=21) underwent a 1.5-T MRI scan prior to and following neoadjuvant chemotherapy with four cycles. Dynamic contrast enhancement was measured using a fast turbo-FLASH sequence and quantified using a two-compartment model with the parameters k(ep) and amplitude. Image analysis was done on images overlayed with a color map of parameters. The correlation between tumor diameter measured by histopathology and MRI was 0.7 (p<0.003). A reduction of tumor size after chemotherapy of more than 25% was associated with a decrease of both analyzed contrast enhancement parameters (k(ep): p<0.002; amplitude: p<0.006), where k(ep) began to drop already after the first cycle of chemotherapy (p<0.008). A clear reduction of tumor size was only noted after the third cycle (p<0.008). In patients without tumor regression there was also a trend towards an early reduction of contrast enhancement. We assume that MRI with high temporal resolution and color mapping is a novel tool to assess therapeutic effects of neoadjuvant chemotherapy in breast tumors, which deserves further prospective evaluation.

Comparison of the efficacy of two air-based contrast agents in dogs

Objective: The aim of this study was to evaluate the differences of the in vivo efficacies of Levovist® (SH U 508 A) and Albunex®, air-based contrast agents (CAs) with different shell materials, by direct comparison. Methods: SH U 508 A, 300 mg/ml, and Albunex® were injected intravenously at doses of 0.1 and 0.15 ml/kg, respectively, into the same dogs ( n=6). Contrast enhancement in the left ventricle was evaluated visually and by off-line measurement of brightness. Results: Both CAs yielded good peak contrast, while the duration of contrast enhancement with SH U 508 A was seven times that with Albunex®. With Albunex®, reduction of contrast enhancement at end-systole and in the late phase of diastole during one heartbeat was observed, and a positive correlation was observed between contrast enhancement and heart rate. Contrast enhancement was nearly constant during one heartbeat with SH U 508 A. Conclusion: SH U 508 A yielded consistent and longer contrast enhancement in the left ventricle than Albunex® under the same conditions.

Non-invasive follow-up of patients with intracranial arteriovenous malformations after proton-beam radiation therapy.

In order better to follow non-invasively the effect of proton beam therapy upon intracranial arteriovenous malformations, transcranial Doppler sonography (TCD) was used in 10 patients, in addition to conventional follow-up with angiography and computed tomography (CT); in six patients, pre- and postradiation TCD studies were obtained. The mean flow values obtained from the major arteries in the circle of Willis indicate an early flow reduction through the AVM of approximately 15% with further reduction between 2/3 and 1/2 of the initial values within 15 months of follow-up. CT showed a reduction of contrast enhancement in those patients in whom scans could be compared. In this limited experience, TCD was proven to yield additional information, in repeated non-invasive studies, on the haemodynamic influence of AVMs and the effect of proton beam therapy.

Transfemoral catheter embolization of intracranial meningiomas. With reference to pathological findings of the tumor

Preoperative embolization has been performed between 1 and 7 days prior to surgery to reduce blood loss during surgical excision of 12 intracranial meningiomas, which possessed predominant external carotid vascularization; 5 convexity, 3 falx, 2 sphenoidal ridge and 2 parasagittal meningiomas. Cerebral catheterizations were performed through the retrograde transfemoral route. The embolization in all cases was effected with pieces of gelfoam in two different sizes, measuring 1×1×1 mm and 2×2×5 mm. The smaller pieces of gelfoam were firstly delivered through a catheter, followed by the larger ones. On computed tomography (CT) scanning after embolization, reduction of contrast enhancement was demonstrated in 9 cases, which coincided with the cases of successful occlusion of the main feeding arteries. On pathological examination of the surgical specimens, fragments of the gelfoam were demonstrated in the arterial lumen of the dura mater attached to the tumor, but no fragments were found in the fine vessels deep within the tumors. There were local or extensive hemorrhagic infarctions with an infiltration of inflammatory cells and acute ischemic necrotic lesions of the tumors with an infiltration of foamy cells. Macroscopic hemorrhage around the tumor was also found in a case. There were marked ischemic lesions in 5 cases and moderate lesions in 3 cases. These pathological findings tended to be more remarkable in the cases, in which main feeders had been occluded completely and the reduction of contrast enhancement had been shown on CT scanning. The pathological evaluation of the tumors suggests the possibility of hemorrhage within and around the tumors after embolization. The results of embolization evaluated on the basis of operative findings were effective in 10 cases. From this study, it was concluded that embolization of the intracranial meningiomas can facilitate the surgery by reducing the great risk of hemorrhage during operation, and that surgical excision of the tumor should be performed as early as possible after embolization.