Comparison of [18 F]fluorocholine and [18 F]fluorodeoxyglucose for positron emission tomography of androgen dependent and androgen independent prostate cancer

PURPOSE: Positron emission tomography (PET) imaging is used for the metabolic evaluation of cancer. [18F]fluorodeoxyglucose (FDG) is commonly used as a radiotracer but its low cellular uptake rate in prostate cancer limits its usefulness. We evaluated the novel choline analog [18F]fluorocholine (FCH) for detecting androgen dependent and androgen independent prostate cancer, and its metastases. MATERIALS AND METHODS: The cellular uptake of FCH and FDG was compared in cultured prostate cancer cells (LNCaP and PC-3). FCH and FDG were injected into nude mice xenografts (CWR-22 and PC-3) and radiotracer uptake in various organs were evaluated. Patients with androgen dependent (9) and independent (9) prostate cancer were studied by FCH and FDG PET. RESULTS: FCH uptake was 849% and 60% greater than FDG uptake in androgen dependent (LNCaP) and independent (PC-3) cells, respectively. The addition of hemicholinium-3 (5 mM.) 30 minutes before radiotracer administration inhibited FCH uptake by 79% and 70% in LNCaP and PC-3 cells, respectively, whereas FDG uptake was not significantly affected. Although nude mice xenografts showed that FDG uptake was equal to or greater than FCH uptake, clinical imaging in patients demonstrated 2 to 4-fold higher uptake of FCH in those with androgen and androgen independent prostate carcinoma (p <0.001). More lesions were detected by FCH than by FDG in primary tumors, osseous metastases and soft tissue metastases. CONCLUSIONS: In vitro data demonstrated greater FCH than FDG uptake in androgen dependent (LNCaP) and androgen independent (PC-3) prostate cancer cells. Although the murine xenograft data showed greater accumulation of FDG than FCH in PC-3 tumors, PET in humans showed that FCH was better than FDG for detecting primary and metastatic prostate cancer. Overall the data from this study suggest that FCH is preferable to FDG for PET of prostate carcinoma and support the need for future validation studies in a larger number of subjects.     

氟脱氧葡萄糖和乙酸盐联合在正电子发射型计算机体层显像诊断肝细胞癌的效能：Meta分析

目的通过meta分析的方法,系统评价^11F—FDG和^11C—Acetate正电子发射型计算机体层扫描联合诊断肝细胞癌的效能。方法使用相关检索词对Medline Pubmed和中国知识基础设施数字图书馆（CNKI）进行检索,收集近年来公开发表的相关中英文文献,并对纳入文献质量进行评分,提取纳入文献的研究数据进行meta分析。结果共有5篇文献纳入本次meta分析。其中英文4篇。中文1篇;对纳入文献进行质量评分,文献得分占总分的78．8％,两种正电子药物联合显像对肝细胞癌的显示率可达到82．9％;肿瘤直径小于2cm、2.5cm之间及5cm以上的肝细胞癌FDG显示阳性率为25％、45．9％、80．9％,Acetate为79．2％、80．1％、78．7％;1、2级分化的肝细胞癌,FDG显示阳性率为48％,Acetate为73．3％;3、4级分化的肝细胞癌,FDG显示阳性率为89．5％,Acetate为86．8％;肝功能Child A级时,FDG显示肝细胞癌的阳性率为59％,Acetate为72％。结论Acetate和FDGPET对肝细胞癌显像有重要的补充作用,二者联合能提高肝细胞癌的显像效能。     

[11C]Metahydroxyephedrine and [18F]Fluorodeoxyglucose Positron Emission Tomography Improve Clinical Decision Making in Suspected Pheochromocytoma

Background Pheochromocytomas are rare tumors of chromaffin cells for which the optimal management is surgical resection. Precise diagnosis and localization may be elusive. We evaluated whether positron emission tomography (PET) scanning with the combination of [¹⁸F]fluorodeoxyglucose (FDG) and the norepinephrine analogue [¹¹C]metahydroxyephedrine (mHED) would allow more exact diagnosis and localization. Methods Fourteen patients with suspected pheochromocytoma were evaluated by anatomical imaging (computed tomography or magnetic resonance imaging) and [¹³¹I]metaiodobenzylguanidine (MIBG) planar imaging. PET imaging was performed by using mHED with dynamic adrenal imaging, followed by a torso survey and FDG with a torso survey. Images were evaluated qualitatively by an experienced observer. Results Eight patients had pathology-confirmed pheochromocytoma. Of the other six, two patients had normal adrenal tissue at adrenalectomy, and the other four had subsequent clinical courses inconsistent with a diagnosis of pheochromocytoma. In four of eight patients with pheochromocytoma, MIBG failed to detect one or more sites of pathology-confirmed disease. The mHED-PET detected all sites of confirmed disease, whereas FDG-PET detected all sites of adrenal and abdominal disease, but not bone metastases, in one patient. MIBG and FDG-PET results were all negative in the six patients without pheochromocytoma. One patient with adrenal medullary hyperplasia had a positive mHED-PET scan. PET scanning aided the decision not to operate in three of six patients. The resolution of PET functional imaging was superior to that of MIBG. Conclusions PET scanning for pheochromocytoma offers improved quality and resolution over current diagnostic approaches. PET may significantly influence the clinical management of patients with a suspicion of these tumors and warrants further investigation. Presented at the 58th Annual Meeting of the Society of Surgical Oncology, Atlanta, Georgia, March 2005.     

18-fluorodeoxyglucose positron emission tomography in predicting survival of patients with pancreatic carcinoma

The prediction of survival of patients with pancreatic cancer is usually based on tumor staging and grading and on the level of tumor markers. However, accurate tumor staging can be obtained only after resection, and still there is a great difference in survival rates among patients with the same clinicopathologic parameters. Recently the uptake of 18-fluorodeoxyglucose (FDG) by positron emission tomography (PET) has been found to be correlated with survival in patients with pancreatic cancer. This study evaluated the role of ¹⁸FDG PET as a prognostic factor for patients with pancreatic cancer. From June 1996 to July 2002, a total of 118 patients underwent PET for pancreatic cancer. The standardized uptake value (SUV) of ¹⁸FDG was calculated in 60 of them, and these patients were divided into high (>4) and low (≦4) SUV groups. They were also evaluated according to the tumor node metastasis (TNM) classification system of the International Union Against Cancer, and by tumor grade, medical or surgical treatment, diabetes, age, sex, and CA19-9 serum levels. Twenty-nine cancers showed high and 31 showed low SUVs. Survival was significantly influenced by tumor stage (P = 0.0001), tumor grade (P = 0.01), and SUV (P = 0.005). Multivariate analysis showed that only stage (P = 0.001) and SUV (P = 0.0002)were independent predictors of survival. When patients who were analyzed for SUV were stratified according to the other variables, FDG uptake was related to survival also after stratification for the following: stage III to IVa (P = 0.002), stage IVb (P = 0.01), tumor resection (P = 0.006), moderately differentiated tumors (P = 0.01), age less than 65 years (P = 0.006), CA 19–9 levels greater than 300 kU/L (P = 0.002), and absence of diabetes (P = 0.0001). The SUV calculated with ¹⁸FDG PET is an important prognostic factor for patients with pancreatic cancer and may be useful in selecting patients for therapeutic management. Presented at the Forty-Fourth Annual Meeting of The Society for Surgery of the Alimentary Tract, Orlando, Florida, May 17–22, 2003 (oral presentation); and the Sixth National Congress of the Italian Association of Nuclear Medicine, Genoa, Italy, November 15–19, 2002.     

Impact of [18F]fluorodeoxyglucose positron emission tomography on surgical management of melanoma patients

BACKGROUND: Several studies have shown adequate sensitivity and specificity of [(18)F]fluorodeoxyglucose positron emission tomography (FDG-PET) for the detection of metastases from melanoma, but few have addressed its impact on treatment. The aim of this retrospective study was to assess the impact of FDG-PET on treatment of melanoma in three Dutch university medical centres. METHODS: The medical records of 257 patients were reviewed. The indications for FDG-PET and findings were recorded. Unexpected findings of suspected (pre)malignant tumours other than melanoma were assessed. Treatment plans before and after FDG-PET were recorded and analysed to evaluate changes in disease management. RESULTS: Most scans (71.2 per cent) were requested for staging, mainly to detect distant metastases in patients with stage III disease. Overall, 56 patients (21.8 per cent) were upstaged as a result of PET. In 44 patients (17.1 per cent) treatment was changed, usually from surgery to systemic treatment in patients with stage III disease. Unexpected tumours were detected (mainly colorectal) in 11 patients (4.3 per cent). CONCLUSION: FDG-PET is most valuable in patients with stage III melanoma for detection of distant metastases and identification of candidates for surgery and/or systemic treatment. Unexpected FDG-PET findings should not be disregarded, as (pre)malignant, clinically relevant, tumours may be identified.     

Serial [18F] fluorodeoxyglucose positron emission tomography after human neuronal implantation for stroke.

OBJECTIVE: There is no known effective treatment for chronic stroke. In this report, we used positron emission tomography (PET) with [18F]fluorodeoxyglucose (FDG) to map the metabolic brain response to neuronal cell implantation in the first human neuroimplantation trial for stroke. METHODS: Twelve patients (nine men, three women; mean age +/- standard deviation, 60.8+/-8.3 yr) with chronic basal ganglia infarction and persistent motor deficit underwent FDG PET within 1 week before and 6 and 12 months after stereotactic implantation of human neuronal cells. Serial neurological evaluations during a 52-week postoperative period included the National Institutes of Health stroke scale and the European stroke scale. RESULTS: Alterations in glucose metabolic activity in the stroke and surrounding tissue at 6 and 12 months after implantation correlated positively with motor performance measures. CONCLUSION: FDG PET performed as part of an initial open-label human trial of implanted LBS-Neurons (Layton BioScience, Sunnyvale, CA) for chronic stroke demonstrates a relationship between relative regional metabolic changes and clinical performance measures. These preliminary findings suggest improved local cellular function or engraftment of implanted cells in some patients.     

Positron-emission tomography with fluorine-18-fluoro-2-deoxy-D-glucose for gallbladder cancer diagnosis

BACKGROUND: Recent advances in hepatobiliary surgery have underscored the need for presurgical diagnosis of gallbladder cancer. Frequently, clinical presentation, biochemical analysis, and structural ultrasound or computed axial tomography images do not enable definitive differentiation of cholecystitis or cholethiasis from gallbladder cancer. The aim of this study was to evaluate the role of fludeoxy glucose-positron-emission tomography (FDG-PET) in establishing the benign or malignant nature of gallbladder lesions. METHODS: A case series of 16 patients with clinical symptoms suggestive of biliary colic or chronic cholecystitis and with inconclusive ultrasound and/or computed axial tomography findings for presence of gallbladder cancer were studied by FDG-PET. RESULTS: FDG-PET showed a sensitivity of 0.80, a specificity of 0.82, and positive and negative predictive values of 0.67 and 0.90, respectively. There was 1 false- negative result in 1 patient with mucinous adenocarcinoma and 2 false-positive results in 1 patient with tuberculoid granulomatous reaction and 1 patient with polypoid lesion with adenomyomatosis. CONCLUSIONS: FDG-PET may be of utility to establish the diagnosis of gallbladder cancer in patients with nonspecific clinical and imaging findings.     

Evaluation of tumor growth in vivo in a rat model of liver metastasis, using a newly devised index obtained by positron emission tomography with [18F] FDG

Background/Purpose [¹⁸F] fluorodeoxyglucose-positron emission tomography (FDG-PET) is regarded as a unique imaging modality, because the images reflect tumor activity. This characteristic of PET encouraged us to use it to develop a novel method of quantitatively measuring liver metastasis viability. Methods F344 rats were injected with rat colon adenocarcinoma cells (RCN-9 cell line) via the portal vein, and some of them were treated with 5-fluorouracil (5-FU). Tumor growth and tumor activity were measured by PET. We used a tumor viability index (TVI) to evaluate changes in tumor activity and to quantitatively evaluate tumor proliferation activity, instead of using the standardized uptake value (SUV) of the tumor tissue. The TVI was compared with the number of tumor nodules and the proliferating cell nuclear antigen (PCNA) index 28 days after RCN-9 cell inoculation. Results [¹⁸F] FDG uptake by the liver tumors was measured by PET, and the TVI was found to increase as the tumor nodules increased in number and size. The TVI values in the experimental model represented the viability of tumors suppressed by chemotherapy, and the values were significantly correlated with the number of nodules and the PCNA index. Conclusions The TVI was concluded to be superior to the SUV, the commonly used indicator, for evaluating tumor growth, especially that of multiple, small tumors.     

Fluorodeoxyglucose positron emission tomography integrated with computed tomography to determine resectability of primary lung cancer

PURPOSE: Fluorodeoxyglucose positron emission tomography integrated with computed tomography (FDGPET/CT) was evaluated as a routine staging technique for primary lung cancer. MATERIALS AND METHODS: We prospectively compared FDG-PET/CT in determining clinical stage and surgical indication with conventional staging not including positron emission tomography (PET). A total of 50 consecutive patients diagnosed with primary lung cancer by cytological or histological examination were studied; 20 of them underwent surgery. RESULTS: Discrepancies between the two staging methods were observed in 14 patients (28%). The stage assigned by PET increased in 12 cases (24%) and decreased in 2 (4%). PET staging was accurate in eight cases with otherwise undetected distant metastases (M1) but was incorrect in six cases, including five where it overdiagnosed nodal metastases (N). Two clinical N3 patients (4%) would have missed a chance of surgery if the surgical indication had been determined by PET staging alone. According to our criteria for surgery, other patients were assigned correctly to surgery by PET staging. The maximum standard uptake value (maxSUV) of all primary lesions ranged from 0 to 23.0 (mean +/- SD, 8.0 +/- 4.4). The mean maxSUV among surgical cases (5.8 +/- 3.6) was significantly smaller than among nonsurgical cases (9.5 +/- 4.2) (P < 0.05). CONCLUSION: Staging examination including FDG-PET/CT and brain magnetic resonance imaging ordinarily can determine the clinical stage and resectability of primary lung cancer. False-positive findings in regional lymph nodes, possibly reflecting past infectious disease, are the most important remaining problem.     

Functional imaging in schizencephaly using [18F]fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) and single photon emission computed tomography with technetium-99m-hexamethyl-propyleneamine oxime (HMPAO-SPECT)

We analyzed interictal [¹⁸F]fluoro-2-deoxy-d-glucose positron emission tomography (FGD-PET) and single photon emission computed tomography with technetium-99m-hexamethyl-propyleneamine oxime (HMPAO-SPECT) in a 23-year-old female with schizencephaly. She had epilepsy and mild left hemiparesis, but was otherwise developmentally normal. We found the glucose metabolism and perfusion of the wall of the schizencephalic cleft to be identical to those of normal cerebral cortex. The wall of the transcerebral clefts, which were observed to be lined by abnormally organized gray matter as a result of a migration disorder, demonstrated gray matter metabolic activity and perfusion. FDG-PET and HMPAO-SPECT were thus found to be a useful complement to magnetic resonance imaging for evaluating schizencephaly. Received: 26 June 1998 / Accepted: 19 August 1998     

Surgical decision for adult optic glioma based on [18F]fluorodeoxyglucose positron emission tomography study

A 51-year-old male presented with a 5-year history of progressive right exophthalmos and visual loss. Magnetic resonance imaging showed a right intraorbital lesion. [(18)F]fluorodeoxyglucose positron emission tomography ([(18)F]FDG-PET) revealed high uptake in the tumor. No FDG was accumulated in the remaining optic tract. He underwent removal of the tumor. The histological diagnosis was optic glioma. Six months after the operation, the tumor recurred, and a second operation was performed to spare the visual acuity of the other eye, which remained stable for 1.5 years after the first operation. However, the patient died 2 years after the first operation of liver dysfunction. Adult optic glioma tends to rapidly extend into the surrounding tissue and to affect the contralateral visual pathway. Early diagnosis and surgical intervention are imperative. In the present case, [(18)F]FDG-PET was valuable for evaluating malignancy to determine whether radical surgery was indicated to preserve the remaining visual acuity.     

Clinical use of fluorodeoxyglucose F 18 positron emission tomography for detection of renal cell carcinoma

PURPOSE: We evaluate the role of fluorodeoxyglucose F 18 positron emission tomography (PET) in patients with renal cell carcinoma (RCC) by retrospective review. To our knowledge this series is the largest reviewing the use of PET in patients with RCC. MATERIALS AND METHODS: A total of 66 patients who underwent 90 PET scans for suspected or known RCC were identified. Dictated reports of PET, chest computerized tomography (CT), abdominal/pelvic CT and bone scan were examined with confirmation of results by histopathology or followup of at least 1 year. The accuracies of PET and conventional imaging modalities were compared. RESULTS: PET exhibited a sensitivity of 60% and specificity of 100% for primary RCC tumors (abdominal CT demonstrated 91.7% sensitivity and 100% specificity). For retroperitoneal lymph node metastases and/or renal bed recurrence, PET was 75.0% sensitive and 100.0% specific (92.6% sensitivity and 98.1% specificity for abdominal CT). PET had a sensitivity of 75.0% and a specificity of 97.1% for metastases to the lung parenchyma compared to 91.1% and 73.1%, respectively, for chest CT. PET had a sensitivity of 77.3% and specificity of 100.0% for bone metastases, compared to 93.8% and 87.2% for combined CT and bone scan. In 39 scans (32 patients) PET failed to detect RCC lesions identified by conventional imaging. CONCLUSIONS: The role of fluorodeoxyglucose F 18 PET in the detection of RCC is limited by low sensitivity. With superior specificity PET may have a complementary role as a problem solving tool in cases that are equivocal on conventional imaging.     

Evaluation of Shoulder Disorders by 2-[F-18]-fluoro-2-deoxy-D-glucose Positron Emission Tomography and Computed Tomography

Background

Although flourine-18-flourodeoxyglucose (FDG) positron emission tomography (PET) has a limitation for localizing anatomical structures, combining it with computed tomography (CT) has made it more efficient for overcoming such limitations. This study aims to evaluate the efficacy of PET/CT for evaluating diseases of the shoulder.

Methods

Retrospective examination was performed on 25 patients who underwent FDG-PET/CT scanning. All the patients were over 60 years of age, and they were evaluated both clinically and radiologically for shoulder pain. The study period was from May, 2006 to May, 2008. One of the patients had metastatic lesion in a shoulder and this patient was excluded from the study, so the total number of subjects in the study was finally 24 patients.

Results

PET/CT showed 67% sensitivity, 73% specificity, a positive predictive value of 60%, a negative predictive value of 79%, 27% false positivity and 33% false negativity concerning shoulder pain. PET/CT showed negative finding in 4 cases that were successfully treated by operative treatment (rotator cuff tear [RCT], 3 cases; impingement syndrome, 1 case). Negative findings were also noted in 6 cases in which the pain subsided after conservative treatment (RCT, 1 case; suspected RCT, 2 cases; impingement syndrome, 3 cases). All the patients with osteoarthritis and rheumatoid arthritis had positive findings on PET/CT scanning.

Conclusions

PET/CT is a useful adjunct to the existing imaging modalities to assess functional and pathophysiologic processes and at a very early stage, and so PET/CT can help physicians make better preoperative and postoperative decisions on treatment.     

Brain tumor imaging with synthesized f-fluorophenylalanine and positron emission tomography

Two patients with cerebral gliomas were studied with ¹⁸F-fluorophenylalanine, newly synthesized by the electrophilic substitution reaction, using positron emission tomography. The tracer accumulated markedly in the tumor lesion and delineated the extent of the lesion. This new tracer will be promising in the diagnosis of gliomas.     

High-resolution fluorodeoxyglucose positron emission tomography with compression ("positron emission mammography") is highly accurate in depicting primary breast cancer

We sought to prospectively assess the diagnostic performance of a high-resolution positron emission tomography (PET) scanner using mild breast compression (positron emission mammography [PEM]). Data were collected on concomitant medical conditions to assess potential confounding factors. At four centers, 94 consecutive women with known breast cancer or suspicious breast lesions received 18F-fluorodeoxyglucose (FDG) intravenously, followed by PEM scans. Readers were provided clinical histories and x-ray mammograms (when available). After excluding inevaluable cases and two cases of lymphoma, PEM readings were correlated with histopathology for 92 lesions in 77 women: 77 index lesions (42 malignant), 3 ipsilateral lesions (3 malignant), and 12 contralateral lesions (3 malignant). Of 48 cancers, 16 (33%) were clinically evident; 11 (23%) were ductal carcinoma in situ (DCIS), and 37 (77%) were invasive (30 ductal, 4 lobular, and 3 mixed; median size 21 mm). PEM depicted 10 of 11 (91%) DCIS and 33 of 37 (89%) invasive cancers. PEM was positive in 1 of 2 T1a tumors, 4 of 6 T1b tumors, 7 of 7 T1c tumors, and 4 of 4 cases where tumor size was not available (e.g., no surgical follow-up). PEM sensitivity for detecting cancer was 90%, specificity 86%, positive predictive value (PPV) 88%, negative predictive value (NPV) 88%, accuracy 88%, and area under the receiver-operating characteristic curve (Az) 0.918. In three patients, cancer foci were identified only on PEM, significantly changing patient management. Excluding eight diabetic subjects and eight subjects whose lesions were characterized as clearly benign with conventional imaging, PEM sensitivity was 91%, specificity 93%, PPV 95%, NPV 88%, accuracy 92%, and Az 0.949 when interpreted with mammographic and clinical findings. FDG PEM has high diagnostic accuracy for breast lesions, including DCIS.     

The role of [18F]fluorodeoxyglucose positron emission tomography imaging in the evaluation of hepatocellular carcinoma

It has been well established that hepatocellular carcinomas (HCCs) accumulate [18F]fluorodeoxyglucose (FDG) to varying degrees; this is thought to be due to differing amounts of FDG-6-phosphatase activity. The purpose of this study was to evaluate the impact of FDG imaging on the management of patients diagnosed with hepatocellular carcinoma. We conducted a retrospective review of the clinical data of 91 consecutive patients diagnosed with HCC who underwent FDG-positron emission tomography (PET) imaging between August 1993 and March 2001. The patients were divided into two groups. In Group one 67 of 91 (74%) patients were evaluated for proven but untreated hepatic lesions using PET. In Group two the remaining 24 patients (26%) were referred for evaluation of HCC recurrence but did not have prior PET. The FDG images were acquired with two dedicated PET tomographs [Siemens ECAT 933, CTI (Knoxville, TN) and GE Advance, General Electric Medical Systems (Milwaukee, WI)] one hour after the intravenous administration of 10 mCi of FDG. Tumor biopsy or resection specimens were available for review from 34 patients and were evaluated for histologic grade, presence of cirrhosis, tumor necrosis, and intratumoral fibrosis. In group one 43 of 67 (64%) of the HCCs accumulated FDG. Sixteen of the 43 patients in whom FDG was accumulated had multiple subsequent FDG-PET scans either for monitoring therapy or for detection of recurrence. FDG-PET imaging had an impact on the management of 20 of these patients: by guiding the biopsy at the metabolically active site of a large necrotic tumor (one), by identifying distant metastases (five), by monitoring the response to treatment with hepatic chemoembolization and guiding additional regional therapy (12), and by detecting recurrence (two). In group two recurrence and/or metastases were demonstrated with FDG-PET imaging in six of 24 (25%) patients, three of whom had multiple subsequent FDG-PET scans to monitor their treatment. Higher histopathologic grade and intratumoral fibrosis but not necrosis or cirrhosis correlated with PET positivity. In this study only 64 per cent of HCCs accumulated FDG. Despite this limitation FDG-PET imaging remains a useful tool in the diagnosis and treatment of HCC. FDG-PET imaging had a clinically significant impact in 26 of 91 (28%) patients with HCC. This includes detection of unsuspected metastatic disease in high-risk patients-including liver transplant candidates-and monitoring response to hepatic-directed therapy. FDG-PET should be considered as part of the workup and management of selected patients with HCC.     

Discrepancy between [18F]fluorodeoxyglucose and 11C-methionine positron emission tomography findings in Sturge-Weber syndrome--case report

Cerebral blood flow and metabolism were evaluated in an adult with symptomatic intractable epilepsy and Sturge-Weber syndrome (SWS) manifesting as angiomas in the left cerebral hemisphere. 99mTc-ethylcysteinate dimer single photon emission computed tomography detected reduced blood flow in the entire left cerebral hemisphere, and [18F]fluorodeoxyglucose positron emission tomography (PET) showed decreased glucose metabolism in the left cerebral hemisphere. These findings indicated hypofunction of the left cerebral hemisphere, which caused the right hemiparesis. 11C-methionine (11C-Met) PET revealed high 11C-Met accumulation in the angiomas in the left cerebral hemisphere. Immunostaining for glial fibrillary acidic protein showed positive reaction in the lesions. Gliosis is a likely mechanism for the 11C-Met accumulation, which is possibly associated with progressive calcification in the angiomas and retarded growth of patients with SWS occurring over many years.