High- and moderately high-methionine uptake demonstrated by PET in a patient with a subacute cerebral infarction

11C-methionine PET/CT findings in benign brain disease

¹¹C-methionine (MET) is one of the most commonly used positron emission tomography (PET) tracers for evaluation of malignant brain tumor, with MET-PET being a sensitive technique for visualization of primary and recurrent malignant brain tumors. However, previous reports have demonstrated MET uptake in lesions associated with benign brain diseases. These diseases usually show an increase in MET uptake similar to that of malignant tumors. This pitfall in MET-PET image interpretation is important not only for nuclear medicine professionals, but also for radiologists. In this review, we demonstrate the imaging characteristics of MET uptake in benign brain disease, and recommend physician interpretation of imaging findings and disease characteristics for optimal patient management. Benign uptake must be identified to prevent misdiagnosis and unnecessary surgical operations.

Clinical interpretation of residual uptake in 11C-methionine positron emission tomography after treatment of basal ganglia germ cell tumors: report of 3 cases

Although (11)C-methionine (MET)-PET has been used to diagnose intracranial germ cell tumors (GCTs) arising in the basal ganglia, whether this imaging technique is useful in assessing treatment response and residual tumor is still unclear. The authors report 3 cases of basal ganglia GCTs in which the residual MET uptake at the end of treatment did not develop into a relapse, even without additional treatment. Case 1 is a 22-year-old man who had a second relapse of a left basal ganglia germinoma with diffuse dissemination on the walls of both of his lateral ventricles. MET-PET revealed high MET accumulation around tumors and their surroundings (maximum standardized uptake value [SUVmax] 3.3). After all treatments, MET-PET demonstrated mild tracer accumulation in both basal ganglia (SUVmax 2.2). Progression-free survival was 56 months from the second relapse without any further treatment. Case 2 is a 17-year-old boy with a left basal ganglia germinoma that showed increased MET uptake (SUVmax 4.2). After treatment, MET-PET revealed residual MET uptake (SUVmax 2.4) along the left posterior limb of the internal capsule. Progression-free survival was 52 months from the start of treatment. Case 3 is a 7-year-old boy with a left basal ganglia choriocarcinoma with increased tumor MET uptake (SUVmax 2.5). A minor enhanced mass remained on MRI after treatment with residual MET accumulation (SUVmax 1.4). Progression-free survival was 44 months. Treatment strategies based on MET uptake on PET should be carefully designed in patients with basal ganglia GCTs to avoid overtreatment and complications.

11C-methionine PET of acute myocardial infarction

Tissue uptake of l-[methyl-(11)C]-methionine ((11)C-methionine) has been used to monitor amino acid metabolism and protein synthesis. We examined whether (11)C-methionine was retained in areas of myocardial infarction after successful reperfusion.

METHODS

Nine patients with infarction in the left anterior descendent region underwent percutaneous transluminal coronary artery intervention within 24 h and (201)Tl SPECT, (18)F-FDG PET, and (11)C-methionine PET within 2 wk of infarction onset. The standardized uptake values of the infarcted area and of the normal area were measured.

RESULTS

The (11)C-methionine images showed increased uptake in the infarcted area, whereas the (201)Tl SPECT and (18)F-FDG PET images showed decreased uptake. The highest accumulation of (11)C-methionine in the infarcted area was observed during the early phase of AMI.

CONCLUSION

(11)C-methionine uptake is elevated in infarcted areas and may reflect the early acute phase of damage healing, that is, the initial process of remodeling.

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.

11C-methionine uptake in cerebrovascular disease: a comparison with 18F-fDG PET and 99mTc-HMPAO SPECT

OBJECTIVES

Carbon-11-L-methyl-methionine (11C-methionine) has been reported to be useful for evaluating brain tumors, but several other brain disorders have also shown signs of high methionine uptake. We retrospectively evaluated the significance of 11C-methionine uptake in cerebrovascular diseases, and also compared our results with those for 18F-FDG PET and 99mTc-HMPAO SPECT.

METHODS

Seven patients, including 3 patients with a cerebral hematoma and 4 patients with a cerebral infarction, were examined. All 7 patients underwent both 11C-methionine PET and 99mTc-HMPAO SPECT, and 6 of them underwent 18F-FDG PET.

RESULTS

A high 11C-methionine uptake was observed in all 3 patients with cerebral hematoma. Increased 99mTc-HMPAO uptake was observed in 2 out of 3 patients, and all 3 patients had decreased 18F-FDG uptake. Of 4 patients with a cerebral infarction, high 11C-methionine uptake was observed in 3. Increased 99mTc-HMPAO uptake was also observed in one patient, whereas 3 patients had decreased 18F-FDG uptake.

CONCLUSIONS

We should keep in mind that high 11C-methionine uptake is frequently observed in cerebrovascular diseases. CVD should therefore be included in the differential diagnosis when encounting patients with a high 11C-methionine uptake.