Chronologic Evaluation of Cerebral Hemodynamics by Dynamic Susceptibility Contrast Magnetic Resonance Imaging After Indirect Bypass Surgery for Moyamoya Disease.

OBJECTIVE: Although indirect bypass surgery is an effective treatment option for patients with ischemic-onset moyamoya disease (MMD), the time point after surgery at which the patient's hemodynamic status starts to improve and the time point at which the improvement reaches a maximum have not been known. The objective of the present study is to evaluate the hemodynamic status time course after indirect bypass surgery for MMD, using dynamic susceptibility contrast-magnetic resonance imaging (DSC-MRI). METHODS: We retrospectively analyzed the cases of 25 patients with MMD (37 sides; mean age, 14.7 years; range, 3-36 years) who underwent indirect bypass surgery and repeated DSC-MRI measurement within 6 months after the operation. The difference in the mean transit time (MTT) between the target regions and the control region (cerebellum) was termed the MTT delay, and we measured the MTT delay's chronologic changes after surgery. RESULTS: The postoperative MTT delay was 1.81 ± 1.16 seconds within 1 week after surgery, 1.57 ± 1.01 at weeks 1-2, 1.55 ± 0.68 at weeks 2-4, 1.32 ± 0.68 at months 1-2, 0.95 ± 0.32 at months 2-3, and 0.77 ± 0.33 at months 3-6. Compared with the preoperative value (2.11 ± 0.98 seconds), the MTT delay decreased significantly from 2 to 4 weeks after surgery (P < 0.05). CONCLUSIONS: The amelioration of cerebral hemodynamics by indirect bypass surgery began soon after surgery and gradually reached a maximum at 3 months after surgery. DSC-MRI detected small changes in hemodynamic improvement, which are suspected to be caused by the initiation of angiogenesis and arteriogenesis in the early postoperative period.

Clinical benefit of 11C methionine PET imaging as a planning modality for radiosurgery of previously irradiated recurrent brain metastases.

OBJECT: Stereotactic radiosurgery with gamma knife (GK-SRS) generally improves the focal control of brain metastases. Yet in cases of focal recurrence at a previous radiation site, MRI is often imperfect in differentiating between active tumor and radiation injury. We have examined whether the use of C methionine (MET) with PET will facilitate this differentiation and improve the outcome of GK-SRS for focally recurrent brain metastases after prior treatment. METHODS: Eighty-eight patients underwent GK-SRS for postirradiation recurrent brain metastases. Thirty-four patients received radiation in areas manifesting high MET uptake (PET group) in a dose-planning procedure using MET-PET/MRI fusion images. Fifty-four patients referred from other institutes received radiation based on dose planning information obtained from MRI (MRI group). RESULTS: Sex, age, and the ratio of breast cancer differed significantly between the MRI and PET groups. The total irradiation volume was significantly smaller in the PET group, and the minimal irradiation dose was significantly higher. In a multivariable statistical analysis, the use of MET-PET (P = 0.02) was independently associated with prolonged overall survival after treatment, Karnofsky performance status (P = 0.002), the number of lesions (P = 0.03), and patient's sex (P = 0.02). The median survival time was significantly longer in the PET group (18.1 months) than in the MRI group (8.6 months) (P = 0.01). CONCLUSION: 11C methionine-PET/MRI fusion images for dose planning lengthened survival in patients undergoing GK-SRS for focally recurrent brain metastases.

Traumatic hematoma of the posterior fossa.

Posterior fossa injury is rare, occurring in less than 3 % of head injuries. We retrospectively reviewed patients' clinical and radiological findings, management, and outcomes. The aim of the present study was to investigate the features of posterior fossa hematoma, including posterior fossa epidural hematoma (EDH), posterior fossa subdural hematoma (SDH), and intracerebellar hematoma. From January 1995 to January 2009, 4,315 patients with head trauma were hospitalized at our institution. The -present study focused on 41 patients (1.0 %) with traumatic hematomas of the posterior fossa. Eighteen patients had EDH, 10 patients had SDH, and 17 patients had intracerebellar hematomas. In each type of injury, occipital bone fractures were seen in many patients, and hematoma enlargement was often observed within a few days of the injury. In addition, a high frequency of associated lesions and a high poor outcome rate were features of intracerebellar hematomas and -posterior fossa SDH. The present study suggests that repeat CT imaging and careful management are necessary until the lesion is stabilized, and patients showing lesions with mass effects should therefore be immediately treated with surgery.

Computed tomography after decompressive craniectomy for head injury.

New findings (NF) on postoperative CTs are -occasionally found in patients who undergo surgery for traumatic brain injury (TBI). We conducted a retrospective -registry-based review of the care of 102 patients who underwent decompressive craniectomy (DC) for TBI to investigate the prognostic factors of new findings on CT early after -surgery. Of the 102 patients, the mean age was 50 years and 69.6 % were male. The overall survival was 72.5 %. The primary indication for DC included subdural hematoma in 72 (70.6 %), epidural hematoma in 17 (16.7 %), and intraparenchymal contusion in 13 (12.7 %). New findings on postoperative CTs were observed in 26 patients (25.5 %). The univariate analysis showed that a GCS score ≤8 (P = 0.012) and the absence of a basal cistern (P = 0.012) were significantly associated with NF on postoperative CT. The logistic regression analysis demonstrated that the GCS score ≤8 (P = 0.041; OR, 3.0; 95 % CI, 1.048-8.517) was the only significant factor. TBI patients with a low GCS score who underwent DC should undergo additional CT evaluations immediately after surgery.

Postoperative computed tomography after surgery for head trauma.

BACKGROUND: It is well known that intracranial lesions, which are already diagnosed on preoperative computed tomography, often expand after surgery, and the risk factors have been investigated. On the other hand, we have experienced cases in which new lesions, which were not detected on preoperative computed tomography, were found on postoperative computed tomography. However, little is known about the factors associated with such new postoperative lesions. Here, we investigated the predictive factors of new findings (NFs) on computed tomography early after surgery. METHODS: We conducted a retrospective registry-based review of 186 consecutive patients who underwent surgery for traumatic brain injury and investigated the prognostic factors of NFs on computed tomography early after surgery. RESULTS: Mean age was 51 years, and 67.2% were males among the 186 patients. NFs on postoperative computed tomography were observed in 29 patients (15.6%). A univariate analysis showed that Glasgow Coma Scale (GCS) score of 8 or less (p < 0.001), subdural hematoma as the primary indication for surgery (p = 0.012), midline shift (p < 0.001), absence of basal cistern (p < 0.001), and decompressive craniectomy and craniotomy as the surgical procedures (p < 0.001, p = 0.004, respectively) were significantly associated with NFs on postoperative computed tomography. A logistic regression analysis demonstrated that decompressive craniectomy as the surgical procedure (p = 0.001; odds ratio [OR], 8.1; 95% confidence interval [CI], 2.23-28.82), GCS score of 8 or less (p = 0.019; OR, 3.4; 95% CI, 1.23-9.52), and absence of basal cistern (p = 0.023; OR, 3.5; 95% CI, 1.19-10.35) were significant factors. CONCLUSION: Early postoperative computed tomography after surgery for head trauma seems to be warranted in patients presenting with the indicated predictive factors of NFs. LEVEL OF EVIDENCE: Prognostic/therapeutic study, level III.

PET pharmacokinetic analysis to estimate boron concentration in tumor and brain as a guide to plan BNCT for malignant cerebral glioma.

INTRODUCTION: To plan the optimal BNCT for patients with malignant cerebral glioma, estimation of the ratio of boron concentration in tumor tissue against that in the surrounding normal brain (T/N ratio of boron) is important. We report a positron emission tomography (PET) imaging method to estimate T/N ratio of tissue boron concentration based on pharmacokinetic analysis of amino acid probes. METHODS: Twelve patients with cerebral malignant glioma underwent 60 min dynamic PET scanning of brain after bolus injection of (18)F-borono-phenyl-alanine (FBPA) with timed arterial blood sampling. Using kinetic parameter obtained by this scan, T/N ratio of boron concentration elicited by one-hour constant infusion of BPA, as performed in BNCT, was simulated on Runge-Kutta algorithm. (11)C-methionine (MET) PET scan, which is commonly used in worldwide PET center as brain tumor imaging tool, was also performed on the same day to compare the image characteristics of FBPA and that of MET. RESULT: PET glioma images obtained with FBPA and MET are almost identical in all patients by visual inspection. Estimated T/N ratio of tissue boron concentration after one-hour constant infusion of BPA, T/N ratio of FBPA on static condition, and T/N ratio of MET on static condition showed significant linear correlation between each other. CONCLUSION: T/N ratio of boron concentration that is obtained by constant infusion of BPA during BNCT can be estimated by FBPA PET scan. This ratio can also be estimated by MET-PET imaging. As MET-PET study is available in many clinical PET center, selection of candidates for BNCT may be possible by MET-PET images. Accurate planning of BNCT may be performed by static images of FBPA PET. Use of PET imaging with amino acid probes may contribute very much to establish an appropriate application of BNCT for patients with malignant glioma.

Glioma surgery using a multimodal navigation system with integrated metabolic images.

OBJECT: A multimodal neuronavigation system using metabolic images with PET and anatomical images from MR images is described here for glioma surgery. The efficacy of the multimodal neuronavigation system was evaluated by comparing the results with that of the conventional navigation system, which routinely uses anatomical images from MR and CT imaging as guides. METHODS: Thirty-three patients with cerebral glioma underwent 36 operations with the aid of either a multimodal or conventional navigation system. All of the patients were preliminarily examined using PET with l-methyl-[11C] methionine (MET) for surgical planning. Seventeen of the operations were performed with the multimodal navigation system by integrating the MET-PET images with anatomical MR images. The other 19 operations were performed using a conventional navigation system based solely on MR imaging. RESULTS: The multimodal navigation system proved to be more useful than the conventional navigation system in determining the area to be resected by providing a clearer tumor boundary, especially in cases of recurrent tumor that had lost a normal gyral pattern. The multimodal navigation system was therefore more effective than the conventional navigation system in decreasing the mass of the tumor remnant in the resectable portion. A multivariate regression analysis revealed that the multimodal navigation system-guided surgery benefited patient survival significantly more than the conventional navigation-guided surgery (p = 0.016, odds ratio 0.52 [95% confidence interval 0.29-0.88]). CONCLUSIONS: The authors' preliminary intrainstitutional comparison between the 2 navigation systems suggested the possible premise of multimodal navigation. The multimodal navigation system using MET-PET fusion imaging is an interesting technique that may prove to be valuable in the future.