Relationship between diffusion-weighted magnetic resonance imaging and histological tumor grading of hepatocellular carcinoma.

BACKGROUND: Intrahepatic and extrahepatic recurrence remains a significant problem for hepatocellular carcinoma (HCC). The aim of this study was to determine the usefulness of diffusion-weighted magnetic resonance imaging (DWI) for histological tumor grading and preoperative prediction of early HCC recurrence within 6 months of operation. METHODS: A total of 44 patients who had undergone hepatic resection for HCC (50 nodules) were reviewed retrospectively. DWI was performed within 30 days before hepatectomy, and apparent diffusion coefficients (ADCs) were measured using 2 methods: mean ADC and minimum-spot ADC. Relationships between ADCs and histological differentiation and between ADCs and early recurrence of HCC were analyzed. RESULTS: Mean ADC was significantly lower in poorly differentiated HCC (n=18, 1.07±0.15×10(-3) mm2/s) than in moderately differentiated HCC (n=29, 1.29±0.21×10(-3) mm2/s; P<.05). Minimum-spot ADC was significantly lower in poorly differentiated HCC (n=18, 0.69±0.19×10(-3) mm2/s) than in well-differentiated HCC (n=3, 1.15±0.10×10(-3) mm2; P<.01) or in moderately differentiated HCC (n=29, 0.98±0.18×10(-3) mm2/s; P<.0001). Of 34 patients who were able to be observed for >6 months after resection, 9 showed early recurrence. Minimum-spot ADC was significantly lower in patients with early recurrence (n=9, 0.64±0.24×10(-3) mm2/s) than in patients without early recurrence (n=25, 0.88±0.19×10(-3) mm2/s; P<.05). On multivariate analysis, minimum-spot ADC was a significant risk factor for early recurrence (P<.05). CONCLUSION: Quantitative measurement of ADC of HCC with magnetic resonance diffusion weighted imaging is a promising functional imaging tool in the prediction of histological grade and early recurrence before treatment.

Pathological study of subacute autoimmune encephalopathy with anti-AQP4 antibodies in a pregnant woman.

A pregnant woman with extensive brain lesions on magnetic resonance imaging was tested positive for anti-aquaporin4 (AQP4) antibodies. An open biopsy of the left temporal lobe showed pathological changes in both the white and gray matter. Hematoxylin and eosin, Klüver-Barrera, and myelin basic protein staining results were indicative of demyelination in the white matter. Loss of AQP4 and glial fibrillary acidic protein was observed in the white matter, and this finding is consistent with the neuropathological findings of neuromyelitis optica spinal lesions. Moreover, loss of AQP4 was observed in the gray matter. The presence of anti-AQP4 antibodies, and the pathology, led to the diagnosis of anti-AQP4 antibodies-related encephalopathy.

Hemorrhagic shock due to spontaneous rupture of adrenal neuroblastoma in an infant: a rare case and review of the literature.

Spontaneous rupture of adrenal neuroblastoma is very rare in infants, in contrast to neonates. This report describes a 9-month-old boy presenting with acute hemorrhagic shock due to spontaneous rupture of adrenal neuroblastoma. MYCN oncogene amplification may be a predisposing factor for spontaneous rupture and bleeding of neuroblastoma. An appropriate surgical treatment for this condition must be discussed according to the patient's general state and the tumor features, such as staging, the origin, and local invasiveness.

Expression of O6-methylguanine DNA methyltransferase (MGMT) and immunohistochemical analysis of 12 pineal parenchymal tumors.

Pineal parenchymal tumors (PPTs) are rare neoplasms which occupy less than 1% of primary CNS tumors. Because of their rare incidence, previous reports on PPTs are limited in number and the useful molecular markers for deciding histological grading and even selecting chemotherapy are undetermined. In this study, we conducted immunohistochemical analysis of 12 PPT specimens, especially for expression of O6-methylguanine DNA methyltransferase (MGMT) to assess whether temozolomide (TMZ) could serve as a possible alternative therapy for PPTs. We analyzed 12 PPTs, consisting of three pineocytomas, six PPTs of intermediate differentiation (PPTIDs), and three pineoblastomas. Immunohistochemical analysis was performed using antibodies against MGMT, synaptophysin, neurofilament protein (NF), p53, and neuronal nuclear antigen (NeuN). Immunohistochemically, 11 out of 12 cases were positive for MGMT. The mean MIB-1 labeling index was less than 1% in pineocytoma, 3.5% in PPTID, and 10.5% in pineoblastoma. All 12 cases were positive for synaptophysin and 11 cases, except one PPTID case, showed positive for NF. Nuclear staining of NeuN was negative in all cases although cytoplasmic staining of NeuN was observed in five cases. No case was positive for p53. Eleven out of 12 cases of PPTs demonstrated MGMT expression, suggesting chemoresistancy to TMZ treatment. This is the first report showing MGMT expression in PPTs. In addition, MIB-1 labeling index correlated with WHO grade, although the immunoreactivity of synaptophysin, NF, NeuN and p53 did not correlate with the histological grade.

Evaluation of extra capsular lymph node involvement in patients with extra-hepatic bile duct cancer.

BACKGROUND: Lymph node metastasis is one of the most important prognostic factors for extra-hepatic bile duct carcinoma (ExHBDC). Extra capsular lymph node involvement (ExCLNI) is the extension of cancer cells through the nodal capsule into the perinodal fatty tissue. The prognostic impact of ExCLNI has been shown to be significant mainly in head and neck malignancies. Recently, the prognostic impacts of ExCLNI have evaluated in gastrointestinal malignancies. However no data is available regarding the incidence and prognostic significance of extra-capsular lymph node involvement (ExCLNI) in resectable ExHBDCs. The aim of the present study is first to evaluate the incidence of ExCLNI in surgically-treated ExHBDCs and second, to determine the prognostic impact of ExCLNI in patients with surgically-treated ExHBDCs. METHODS: A total of 228 patients (110 cases of hilar cholangiocarcinoma and 118 cases of distal cholangiocarcinoma) with surgically-treated ExHBDCs were included in this retrospective study. ExCLNI was defined as the extension of cancer cells through the nodal capsule into the perinodal fatty tissue. The existence of ExCLNI and its prognostic value were analyzed as a subgroup of lymph node metastasis. RESULTS: ExCLNI was detected in only 22% of patients with lymph node metastasis of surgically-treated ExHBDC. The presence of ExCLNI correlated with distal cholangiocarcinoma (p = 0.002). On univariate analysis for survival, perineural invasion, vascular invasion, histological grade, and lymph node metastasis were statistically significant factors. On multivariate analysis, only lymph node metastasis was identified as a significant independent prognostic factor in patients with resectable ExHBDC. Subgroups of lymph node metastasis including the presence of ExCLNI, location of lymph node metastasis, and the number of lymph node metastasis had no statistically significant impact on survival. CONCLUSION: ExCLNI was present in only 22% of the LNM (7% of overall patients) in patients with surgical treated ExHBDCs. And ExCLNI would have no impact on the survival of patients with surgically-treated ExHBDCs.

Expression of chemerin in intestinal mucosa of calves with comparable expression level with other antimicrobial proteins.

Neonatal calves are highly susceptible to infectious disorders including diarrhea. Therefore, epithelial innate immunity, including antimicrobial peptides/proteins (AMPs), is important during the early stage of their lives. Chemerin, a multifunctional protein that was originally identified as a chemokine, possesses a potent antimicrobial activity. The present study investigated the expression levels of chemerin in the gastrointestinal (GI) tract of growing calves. Chemerin and its coding gene, retinoic acid receptor responder protein 2 (RARRES2), were highly expressed in duodenum, jejunum, and ileum compared with other parts of the GI tract. Immunohistochemistry demonstrated that chemerin-producing cells were localized in the crypt of the intestinal mucosa. Finally, the expression level of RARRES2 was higher compared with those of other major AMPs in duodenum, although it was lower compared with that of enteric ß-defensin but mostly higher than those of other AMPs in jejunum and ileum at various ages in calves. The expression levels of RARRES2 were not influenced by the age of calves in duodenum and jejunum, whereas a higher expression level of RARRES2 in ileum was observed in younger calves. This study revealed that chemerin is produced in the small intestine of calves and has the potential to contribute to the gut epithelial barrier system.

Large T antigen promotes JC virus replication in G2-arrested cells by inducing ATM- and ATR-mediated G2 checkpoint signaling.

Large T antigen (TAg) of the human polyomavirus JC virus (JCV) possesses DNA binding and helicase activities, which, together with various cellular proteins, are required for replication of the viral genome. We now show that JCV-infected cells expressing TAg accumulate in the G(2) phase of the cell cycle as a result of the activation of ATM- and ATR-mediated G(2) checkpoint pathways. Transient transfection of cells with a TAg expression vector also induced G(2) checkpoint signaling and G(2) arrest. Analysis of TAg mutants with different subnuclear localizations suggested that the association of TAg with cellular DNA contributes to the induction of G(2) arrest. Abrogation of G(2) arrest by inhibition of ATM and ATR, Chk1, and Wee1 suppressed JCV genome replication. In addition, abrogation of the G(2)-M transition by Cdc2 depletion disabled Wee1 depletion-induced suppression of JCV genome replication, suggesting that JCV replication is facilitated by G(2) arrest resulting from G(2) checkpoint signaling. Moreover, inhibition of ATM and ATR by caffeine suppressed JCV production. The observation that oligodendrocytes productively infected with JCV in vivo also undergo G(2) arrest suggests that G(2) checkpoint inhibitors such as caffeine are potential therapeutic agents for JCV infection.

A case of progressive thrombotic microangiopathy after ABO-incompatible renal transplantation.

A 21-yr-old man of blood type O receiving hemodialysis for IgA nephropathy underwent living-related ABO-incompatible (ABOI) renal transplantation from his mother, whose blood type is A. He was negative for flow cross-match, anti-human leukocyte antigen (HLA) antibody, and anti-MICA antibody. Pre-treatment anti-A IgG titer was 1:256. Desensitization consisted of tacrolimus, mycophenolate mofetil, methylprednisolone, rituximab, and plasmapheresis. He developed acute antibody rejection at day 2 post-transplant, which was successfully treated. After renal artery reconstruction surgery at day 91 for renovascular hypertension caused by renal artery stricture, the patient suffered from acute prostatitis, which subsequently induced type III acute antibody-mediated rejection. Even after recovery from the rejection after temporary hemodialysis, graft function progressively deteriorated and consecutive allograft biopsy showed progressive thrombotic microangiopathy (TMA) without any evidence of donor-specific antibody other than anti-A antibody. The tacrolimus dose was kept low for fear of tacrolimus-induced TMA. Despite these efforts, the patient resumed hemodialysis six months' post-transplant.

Clinicopathological analysis of early-stage gastric cancers detected after successful eradication of Helicobacter pylori.

BACKGROUND AND AIMS: The results of a randomized controlled study and meta-analysis study have recently proved that Helicobacter pylori eradication has a preventive effect against the development of metachronous and primary gastric cancer. However, gastric cancer is sometimes detected after successful eradication. There is a lack of study about gastric cancers in eradicated patients. To clarify the characteristics of gastric cancers detected after H. pylori eradication, we analyzed the clinicopathological features of these cancers. METHODS: The subjects were 18 early-stage gastric cancer specimens resected from 17 patients who had received successful eradication of H. pylori from February 1995 to March 2009. The control group consisted of 36 specimens from noneradicated patients with persistent H. pylori infection who were matched with the subjects in age, sex, and depth of invasion. Clinicopathological features and mucin phenotypes of gastric cancer were clinically and immunohistologically evaluated. RESULTS: The average diameter of gastric cancer was smaller and Ki-67 index was lower in the eradication group. The morphological distribution of depression types was significantly lower in the control group. Immunohistochemical phenotyping revealed that 72.2% of the lesions in the eradicated group were complete gastric type or gastric predominant mixed type, whereas the percentages of gastric type and intestinal type in the control group were similar. CONCLUSION: Our findings indicate that the clinicopathological characteristics of gastric cancers detected after H. pylori eradication are different from those of gastric cancers in patients with persistent H. pylori infection. H. pylori eradication may suppress intestinalization during the development of gastric cancer.

Extensively spreading intraepithelial bile duct carcinoma causing multiple bile duct strictures: report of three cases.

Extensive intraepithelial spread of bile duct carcinoma is a common feature, seen in approximately 18% of all cases. However, this spread is rarely accompanied by bile duct strictures. We herein describe three cases of bile duct carcinoma with multiple bile duct strictures due to extensive intraepithelial spread. In all three cases, the spread of intraepithelial cancer extended into the epithelium of the peribiliary glands along the intrahepatic bile ducts with marked fibrosis on histopathological examination. It is speculated that peribiliary gland involvement by superficially spreading bile duct cancer and subsequent obstructive glandular inflammation with fibrosis might cause intrahepatic bile duct strictures even without interstitial cancer invasion.

A case of immunoglobulin 4-related disease with bilateral mass-forming lesions in the nasolacrimal ducts.

This case study describes a 58-year-old man with watery eyes, bilateral swelling of the ala nasi and submandibular glands, and a swollen right parotid gland. Computed tomography revealed mass-forming lesions in both nasolacrimal ducts, extending bilaterally to the lacrimal sac and inferior meatus in the nose. Pathologic investigation showed marked infiltrates of immunoglobulin 4 (IgG4)-positive plasma cells in the nasolacrimal duct lesion, which led us to diagnose IgG4-related disease. Oral prednisolone improved the symptoms of watery eyes and the bilateral swelling of the nasolacrimal duct and salivary gland enlargement. To the best of our knowledge, this is the first report of IgG4-related disease involving mass-forming lesions in the nasolacrimal ducts.

[Gliomatosis cerebri with multifocal progressive lesions on MRI].

A 77-year-old woman with cognitive impairment and multifocal progressive lesions on brain MRI was admitted to our hospital. Analysis of blood and cerebrospinal fluid showed no evidence of infection, autoimmune disease, or metabolic abnormalities. Histological examination of biopsied tissue from a lesion in the right frontal lobe revealed an abnormally increased glial cell density with enlarged nuclei and a high MIB-1 index. These pathological findings coupled with her progressive clinical history indicated a diagnosis of gliomatosis cerebri. General characteristics of gliomatosis cerebri include diffuse infiltrative lesions in neuroimaging with or without mass effect. However, the present case showed unusual multifocal manifestations in brain MRI. Therefore, histopathological examination must be taken into account for a proper diagnosis.

[A rare case of diffuse astrocytoma complicated with giant pigmented hairy nevi, suspected neurocutaneous melanosis].

A 1-year-old female infant presented with congenital giant, hairy and pigmented nevi. MRI scan as screening test revealed a cerebellar tumor. A diagnosis of provisional neurocutaneous melanosis was made on the basis of the patient's MRI and physical findings. At her 6 years of age, MRI revealed the tumor grown up to 3 cm diameter in 5 years. The cerebellar tumor was removed partially using the occipital transtentorial approach for tissue diagnosis. The color of the cerebellar tumor was whitish and contained neither benign nor malignant melanocyte. Pathological examination revealed diffuse astrocytoma. Finally residual cerebellar tumor was totally removed at a second surgical resection. To our knowledge, this is the first patient to be reported with astrocytoma complicated giant skin nevus except neurocutaneous syndrome cases.

[A case of metastatic choroid plexus tumor from cholangiocellular carcinoma].

Metastatic intraventricular tumor located in the choroid plexus is very rare. Only a few cases have been reported in the past. According to past reports, these tumors originated from lung, colon, and so on, but not from the bile duct. This is the first case report of choroid plexus metastasis from cholangiocellular carcinoma. A 57-year-old woman who had a history of cholagiocellular carcinoma, demonstrated intraventricular tumor. Although sufficient examination was performed, the tumor was difficult to diagnose as being a metastatic tumor or a choroid plexus carcinoma. Because of this, we performed endoscopic biopsy of the intraventricular tumor. However intraoperative findings were not helpful in distinguishing metastatic tumor and choroid plexus carcinoma. Postoperatively, histological examination was performed. However it was still difficult to differentiate this rare tumor from choroid plexus carcinoma by only hematoxylin and eosin stain. For further examination, Ber EP-4 stain was performed. Ber EP-4 showed strongly positive which indicates metastatic tumor. This method led us to make an appropriate diagnosis of this extremely rare tumor. We considered that in order to diagnose this rare tumor, appropriate histopathological examination, including immunohistopathological examination should be performed.

Impact of diagnostic ureteroscopy on intravesical recurrence and survival in patients with urothelial carcinoma of the upper urinary tract.

PURPOSE: We determined whether diagnostic ureteroscopy for upper urinary tract cancer affects intravesical recurrence and cancer specific mortality. MATERIALS AND METHODS: In a retrospective, multi-institutional study we evaluated 208 patients undergoing nephroureterectomy for upper urinary tract cancer who had no perioperative systemic chemotherapy, history of invasive bladder cancer, distant metastasis or incomplete followup data. Of these 208 patients 55 who composed the study group underwent diagnostic ureteroscopy before nephroureterectomy while 153 serving as controls did not. We analyzed intravesical recurrence and cancer specific survival using the Kaplan-Meier method with the log rank test used to assess significance. RESULTS: There was no significant difference between the 2 groups in patient characteristics or upper urinary tract cancer stage and grade while followup, and the proportion of multiple tumors and lymphovascular invasion positive tumors were significantly greater in controls. The 2-year bladder recurrence-free survival rate was 60.0% in the study group and 58.7% in controls. There was no significant difference in the intravesical recurrence rate between the 2 groups (log rank test p = 0.972). Estimated Kaplan-Meier cancer specific survival was 88.3% and 78.1% at 5 years in the study and control groups, respectively (log rank test p = 0.0687). CONCLUSIONS: Diagnostic ureteroscopy did not affect intravesical recurrence or cancer specific survival in patients with upper urinary tract cancer undergoing nephroureterectomy.

Pathological characteristics and clinical course of bladder tumour developing after nephroureterectomy.

OBJECTIVES: To determine the pathological features and clinical course of intravesical recurrence after nephroureterectomy (NU) for upper urinary tract (UUT) cancer. PATIENTS AND METHODS: Among 325 patients undergoing NU with bladder cuff excision for UUT cancer, in this retrospective multi-institutional study we evaluated 113 who developed bladder tumour after NU. Excluding patients with (i) perioperative systemic chemotherapy or radiotherapy for UUT cancer; (ii) a history of previous or synchronous bladder cancer at the time of NU; (iii) distant metastasis at the time of NU; (iv) a follow-up of <1 year after the initial bladder cancer recurrence; or (v) missing data, 74 patients were included in this study. We compared the pathology between UUT cancer and the first bladder cancer recurrence, using Fisher's exact test. Further intravesical recurrence and bladder cancer progression was analysed using the Kaplan-Meier method, with the log-rank test used to assess significance. A Cox proportional hazard model was used for multivariate analysis. RESULTS: The grade of the first bladder cancer recurrence strongly correlated with that of the UUT tumour (P < 0.001) and the carcinoma in situ (CIS) lesion with the first bladder cancer recurrence correlated with high grade (grade 3) UUT tumour (P < 0.001). In all, 56 of the assessable 70 patients further developed intravesical recurrence at a median interval of 7 months after the first bladder cancer recurrence. There were no clinicopathological factors that predicted the second recurrence. Progression occurred in 14 patients, at a median interval of 25 months. A CIS lesion with the first bladder cancer recurrence was a risk factor for progression on multivariate analysis. CONCLUSIONS: A large proportion of the patients who developed bladder tumour after NU had further intravesical recurrence, which indicated its refractory nature. Especially when a CIS lesion is detected in the initial intravesical recurrence, a careful follow-up is mandatory to detect bladder cancer progression.

Low-grade dysplasia component in early invasive squamous cell carcinoma of the esophagus.

BACKGROUND AND AIMS: It has not been determined whether low-grade squamous dysplasia (LGD) of the esophagus is a precancerous lesion or not. If LGD progresses to squamous cell carcinoma, early carcinoma lesions that have such a natural history might contain a remaining LGD component. METHODS: The lesions in the 68 patients with early invasive squamous cell carcinoma who underwent endoscopic mucosal resection were examined for the presence of an LGD component. If LGD components were observed, the degrees of architectural and cytological abnormalities of LGD components and those of tumor invasive fronts in the same lesions were studied. The degrees of abnormalities of 28 small LGD lesions were also studied. RESULTS: Histological examination of resected specimens confirmed LGD components in 43% of the squamous cell carcinoma lesions. The lesions of lamina propria mucosae (m2) cancer contained a significantly broader area of LGD component than did the lesions of muscularis mucosae (m3) and submucosal layer (sm) cancer (P = 0.037). Mean score for the degrees of cytological abnormalities of LGD component was similar to that of tumor invasive front (P = 0.457) and significantly higher than that of small LGD lesions (P < 0.001). CONCLUSION: Our results indicate the possibility that the lesion was formed by a combination of small lesions that arose as a multicentric occurrence of squamous cell carcinoma and dysplasia. Our results also suggest that an LGD component would transform to carcinoma along with tumor progression. However, the concept of 'basal cell layer type carcinoma in situ' may be suitable for squamous cell lesions with a high degree of cytological abnormalities confined to the lower half of the epithelium.

IgG4-related sclerosing cholangitis and autoimmune pancreatitis: histological assessment of biopsies from Vater's ampulla and the bile duct.

BACKGROUND AND AIM: Autoimmune pancreatitis is commonly associated with immunoglobulin (Ig) G4-related sclerosing cholangitis (IgG4-SC). The discrimination between IgG4-SC and pancreatobiliary malignancies or primary sclerosing cholangitis (PSC) is now an important issue. The present study was carried out to examine the usefulness of endoscopic biopsies from Vater's ampulla and the bile duct to diagnose IgG4-SC. METHODS: The present study included 29 IgG4-SC patients (26 with both pancreatitis and cholangitis, and 3 with cholangitis only), 6 PSC patients, and 27 pancreatobiliary carcinoma patients. All patients underwent endoscopic biopsies from Vater's ampulla and the common bile duct. Biopsied specimens were histologically examined using immunostaining for IgG4. RESULTS: For the ampullary and bile duct biopsies, the IgG4-SC samples had a significantly greater number of IgG4-positive plasma cells than the PSC or pancreatobiliary carcinoma specimens. In addition, bile duct biopsies from five patients (17%) with IgG4-SC showed diffuse inflammatory cell infiltration with irregular fibrosis corresponding to the histological features of lymphoplasmacytic sclerosing pancreatocholangitis. Based on the threshold of 10 IgG4-positive plasma cells per high power field, the diagnostic rates of the ampullar and bile duct biopsies were both 52% (15/29 cases). Twenty-one patients (72%) had more than 10 IgG4-positive plasma cells in at least one biopsy. The bile duct biopsy was significantly valuable for IgG4-SC patients with swelling of the pancreatic head. CONCLUSION: The present study suggested that ampullar and bile duct biopsies are useful for diagnosing IgG4-SC.

Long-term treatment of localized gastric marginal zone B-cell mucosa associated lymphoid tissue lymphoma including incidence of metachronous gastric cancer.

BACKGROUND AND AIM: According to a few recent reports on the long-term clinical outcome of gastric marginal zone B-cell mucosa associated lymphoid tissue lymphoma (MALT lymphoma); localized gastric MALT lymphoma generally has a favorable prognosis. However, the risk of metachronous gastric cancer has not been evaluated. In this study, we analyzed long-term outcomes of localized gastric MALT lymphoma including the incidence of metachronous gastric cancer. METHODS: Between April 1996 and May 2008, 60 patients (31 men and 29 women; mean age 58.1 years) with localized gastric MALT lymphoma (stage I and II(1) according to Lugano classification) were analyzed retrospectively. RESULTS: Forty-eight patients (82.6%) achieved complete remission by eradication therapy. Radiation therapy was conducted on eight patients as second-line treatment, and all of them achieved remission. The median follow-up period was 76 months (range, 12-157 months). One patient had local relapse after remission for 5 years and three patients developed early gastric cancer without recurrence of lymphoma (5%). All of the three gastric cancers appeared in the same areas where MALT lymphoma had been eradicated. CONCLUSION: Eradication therapy and radiation therapy for localized gastric MALT lymphoma have a favorable long-term outcome, though regular follow-up endoscopy should be performed for detecting metachronous early gastric cancer.

[Combined use of positron emission tomography with (18)F-fluorodeoxyglucose and (11)C-methionine for preoperative evaluation of gliomas].

OBJECT: The aim of this study was to evaluate the usefulness of combined use of positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) and (11)C-methionine (MET) for the preoperative evaluation of gliomas and to investigate the feasibility of PET in glioma surgery. METHODS: Preoperative FDG (n=25) and/or MET (n=22) PET studies were performed in 26 patients with primary and recurrent adult gliomas. We qualitatively (visual analysis) and quantitatively evaluated the uptake of both tracers in the tumor location. For quantitative analysis, data were analyzed by a region of interest method using the standard uptake value (SUV) and a calculated uptake ratio. We investigated the correlation among the tracer uptake ratios, histological tumor grading and tumor proliferation activity. RESULTS: On visual inspection, no patient (0/9) with high uptake of FDG had low grade gliomas and 94% (14/15) had high grade gliomas, while uptake of MET was present in all patients. On quantitative analysis, histological tumor grade was most reflected in FDG uptake ratio compared with contralateral white matter. The tumor/normal brain (T/N) uptake ratio of MET increased stepwise with increasing histological grade but was not significantly different from tumor grade. In comparison of FDG and MET uptake ratio with proliferation activity, a significant correlation was shown for FDG uptake ratio, but not for the T/N ratio of MET. CONCLUSIONS: MET is useful in detecting and delineating the extent of the tumor, but not in evaluating tumor grade and proliferative activity. The FDG uptake ratio correlates well with tumor grade and proliferative activity. Preoperative PET studies with FDG and MET play complementary roles in the planning of glioma surgery, and integrated information from both tracers helps us to plan the extent of tumor resection.