Value of 11C-methionine PET in imaging brain tumours and metastases.

(11)C-methionine (MET) is the most popular amino acid tracer used in PET imaging of brain tumours. Because of its characteristics, MET PET provides a high detection rate of brain tumours and good lesion delineation. This review focuses on the role of MET PET in imaging cerebral gliomas. The Introduction provides a clinical overview of what is important in primary brain tumours, recurrent brain tumours and brain metastases. The indications for radiotherapy and the results and problems arising after chemoradiotherapy in relation to imaging (pseudoprogression or radionecrosis) are discussed. The working mechanism, scan interpretation and quantification possibilities of MET PET are then explained. A literature overview is given of the role of MET PET in primary gliomas (diagnostic accuracy, grading, prognosis, assessment of tumour extent, biopsy and radiotherapy planning), in brain metastases, and in the differentiation between tumour recurrence and radiation necrosis. Finally, MET PET is compared to other nuclear imaging possibilities in brain tumour imaging.

(123)I-Labelled metaiodobenzylguanidine for the evaluation of cardiac sympathetic denervation in early stage amyloidosis.

PURPOSE: Cardiac amyloidosis is a rare disorder, but it may lead to potentially life-threatening restrictive cardiomyopathy. Cardiac manifestations frequently occur in primary amyloidosis (AL) and familial amyloidosis (ATTR), but are uncommon in secondary amyloidosis (AA). Echocardiography is the method of choice for assessing cardiac amyloidosis. Amyloid deposits impair the function of sympathetic nerve endings. Disturbance of myocardial sympathetic innervations may play an important role in the remodelling process. (123)I-MIBG can detect these innervation changes. METHODS: Patients with biopsy-proven amyloidosis underwent general work-up, echocardiography and (123)I-MIBG scintigraphy. Left ventricular internal dimensions and wall thickness were measured, and highly refractile cardiac echoes (sparkling) were analysed. Early (15 min) and late (4 h) heart-to-mediastinum ratio (HMR) and wash-out rate were determined after administration of MIBG. RESULTS: Included in the study were 61 patients (30 women and 31 men; mean age 62 years; 39 AL, 11 AA, 11 ATTR). Echocardiographic parameters were not significantly different between the groups. Sparkling was present in 72 % of ATTR patients, in 54 % of AL patients and in 45 % of AA patients. Mean late HMR in all patients was 2.3 ± 0.75, and the mean wash-out rate was 8.6 ± 14 % (the latter not significantly different between the patient groups). Late HMR was significantly lower in patients with echocardiographic signs of amyloidosis than in patients without (2.0 ± 0.70 versus 2.8 ± 0.58, p < 0.001). Wash-out rates were significantly higher in these patients (-3.3 ± 9.9 % vs. 17 ± 10 %, p < 0.001). In ATTR patients without echocardiographic signs of amyloidosis, HMR was lower than in patients with the other types (2.0 ± 0.59 vs. 2.9 ± 0.50, p = 0.007). CONCLUSION: MIBG HMR is lower and wash-out rate is higher in patients with echocardiographic signs of amyloidosis. Also, (123)I-MIBG scintigraphy can detect cardiac denervation in ATTR patients before signs of amyloidosis are evident on echocardiography.

Bone scintigraphy with (99m)technetium-hydroxymethylene diphosphonate allows early diagnosis of cardiac involvement in patients with transthyretin-derived systemic amyloidosis.

OBJECTIVE: To assess the usefulness of bone scintigraphy with (99m)Technetium-hydroxymethylene diphosphonate ((99m)Tc-HDP) for the detection of cardiac involvement in a group of patients with ATTR amyloidosis in different phases of disease, to relate the findings to echocardiography, ECG and cardiac biomarkers, and to evaluate different bone scintigraphic techniques and calculation methods for quantification of the cardiac uptake and for correlation with echocardiographic features and cardiac biomarkers. METHODS: Forty-one patients underwent clinical examinations, echocardiography, ECG, measurement of cardiac biomarkers and bone scintigraphy (planar imaging and SPECT-CT) and were subsequently subdivided into three groups: (1) carriers of an amyloidogenic TTR mutation, n = 11, (2) proven ATTR amyloidosis without echocardiographically-defined (mean wall thickness >12 mm) cardiac amyloidosis (AC), n = 19, and (3) ATTR amyloidosis with echocardiographically-defined cardiac amyloidosis, n = 11. Planar and SPECT-CT images were analyzed visually according to a routine scoring system (grade 0-3) and semi-quantitatively by heart-to-whole body (H/WB) and heart-to-skull (H/S) ratio on planar images and by a left ventricle-blood pool ratio on SPECT-CT images. RESULTS: All patients with ATTR and echocardiographically-defined AC and none of the carriers showed high cardiac uptake on bone scintigraphy. Furthermore, 8 out of 19 patients with ATTR without echocardiographically-defined AC showed high cardiac uptake. Highest correlations were found between H/S ratio on planar bone scintigraphy with troponin T (r = 0.76, p < 0.0001) and H/WB ratio with left ventricular mass index (r = 0.73, p < 0.0001). CONCLUSIONS: Bone scintigraphy with (99m)Tc-HDP may detect cardiac involvement in patients with ATTR amyloidosis prior to echocardiographic evidence of cardiac involvement. Cardiac uptake on bone scintigraphy correlates with severity of cardiac involvement using echocardiography, ECG and cardiac biomarkers. Visual grading and calculation of H/S ratio on planar imaging are the preferred methods to assess cardiac uptake.