99mTc-MIBI Single-photon Emission Tomography Research Articles

Monitoring the chemotherapeutic response in primary lung cancer using (99m)Tc-MIBI SPET.

Prediction and evaluation of the response to chemotherapy (CTx) are important for the correct and cost-effective treatment of patients with primary lung cancer. Although fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) is accepted as the most useful and accurate nuclear medicine technique for this purpose, its expense and limited availability restrict its use. Compared with PET agents, technetium-99m methoxyisobutylisonitrile (MIBI), which is used in nuclear oncology, is cheaper and available in any nuclear medicine clinic. With this in mind, in this study we aimed to evaluate the role of (99m)Tc-MIBI in monitoring the chemotherapeutic response in primary lung cancer. Twenty patients with primary lung cancer underwent (99m)Tc-MIBI single-photon emission tomography (SPET) at 15min (early) and 3-4h (delayed) after injection of the tracer. All patients underwent (99m)Tc-MIBI SPET study twice: before and after the 3rd cycle of CTx. Patients were divided into two groups, responders [R(+), n=10] and non-responders [R(-), n=10], according to the change in tumour size on CT scan taken 2 weeks after the last cycle of the CTx. From the SPET images early and delayed tumour/lung ratios (ER and DR) were obtained before and after CTx. In the R(+) group, ER and DR decreased significantly after CTx, from 3.28±1.55 to 1.78±0.72 (P<0.04) and from 3.23±1.55 to 2.0±0.88 (P<0.05), respectively. However, in the R(-) group, while ER showed a slight and statistically insignificant increase after CTx (from 2.51±1.23 to 2.65±1.86), DR increased significantly, from 2.74±1.37 to 3.27±2.31 (P<0.03). The percentage decreases in ER and DR in the R(+) group after CTx was significantly higher than that in the R(-) group: 34.36%±26.7% vs -13.78%±27.58% (P<0.0002) and 29.45%±25.23% vs -18.58%±20.51% (P<0.0005), respectively. Using a decrease of ≥10% as a threshold for monitoring the chemotherapeutic response, (99m)Tc-MIBI had a sensitivity of 90% and a specificity of 100%. We found a positive correlation in 14 patients between ER and DR and survival: r=0.6754 and P=0.008, and r=0.5755 and P=0.031, respectively. Our results suggest that (99m)Tc-MIBI might be used in routine practice to monitor the chemotherapeutic response in patients with primary lung cancer, especially when PET is not available.

A comparison of99mTc-MIBI myocardial SPET with electron beam computed tomography in the assessment of coronary artery disease

We compared technetium-99m methoxyisobutylisonitrile (MIBI) myocardial perfusion single-photon emission tomography (SPET) (MPS) and electron beam computed tomography (EBCT) in order to assess their respective value in the detection of coronary artery disease (CAD). 99mTc-MIBI SPET (stress-resting) and EBCT studies were performed in 51 patients with suspected CAD who underwent coronary angiography (CAG). CAG showed that of the 51 patients, 36 had coronary stenosis >/=50% while 15 had normal results. A moderate positive rank correlation was found between coronary calcification detected by EBCT and MPS score (rs=0.5283, P<0.01). The concordance between EBCT and MPS for the evaluation of CAD was 72.5% (37/51). The sensitivity of EBCT in detecting CAD in 51 patients was comparable to that of MPS (81% vs 94%, NS). However, the accuracy of EBCT was lower than that of MPS (78% vs 94%, P<0.025). As regards the detection of individual coronary artery disease, there was no significant difference in sensitivity between EBCT and MPS (65% vs 75%, NS); however, the specificity and accuracy of EBCT were lower than those of MPS (specificity: 77% vs 95%, P<0.005; accuracy 71% vs 85%, P<0.005). The sensitivity, specificity and accuracy of MPS in detecting single-vessel disease were higher than those of EBCT (sensitivity: 86% vs 42%, P<0.025; specificity: 96% vs 70%, P<0.025; accuracy: 93% vs 61%, P<0.005). However, no significant differences in the sensitivity, specificity and accuracy of MPS and EBCT were found in respect of multivessel disease. 99mTc-MIBI myocardial perfusion SPET and EBCT provide different information in the assessment of CAD. The sensitivity of EBCT for the detection of CAD is comparable with that of MPS; however, the specificity and accuracy of EBCT are lower than those of MPS. More reliable results will be obtained if both myocardial perfusion SPET and EBCT are performed.

Dobutamine 99mTc-MIBI single-photon emission tomography: non-exercise-dependent detection of haemodynamically significant coronary artery stenoses

Dobutamine pharmacological stress testing in conjunction with technetium-99m methoxyisobutylisonitrile single-photon emission tomography (MIBI SPET) may be a useful alternative to convential exercise stress MIBI SPET for the detection and localisation of coronary artery stenoses. Therefore, 35 patients with stenoses (> or = 50% diameter reduction) of one or more coronary arteries were selected for dobutamine MIBI SPET. Each patient underwent MIBI injection at rest and during dobutamine infusion with incremental doses (5, 10, 15 and 20 micrograms kg-1 min-1). A conventional exercise stress test (EST) was performed in all patients. Peak double product during steady-state dobutamine infusion (18,200 +/- 4200 mmHg min-1) was lower (P = 0.0001) than during EST (21,700 +/- 4900 mmHg min-1). Image quality was good in all but one patient, who had to be excluded from data analysis due to excessive hepatobiliary MIBI activity. Dobutamine-induced perfusion abnormalities were observed in 30/34 MIBI SPET studies, resulting in an overall detection rate for coronary artery disease of 88%. A pathological EST was observed in 23/34 patients (68%). The detection rate of individual coronary artery stenoses was 85% (28/33) for stenosess with a severe diameter reduction (> 70%) and 50% (12/24) for stenoses with a moderate diameter reduction (> or = 50-70%). In particular, sensitivity and specificity for the detection of moderate and severe stenoses (> or = 50%) were 75%/100% for left anterior descending, 67%/95% for left circumflex and 67%/69% for right coronary artery stenoses. Dobutamine MIBI SPET is a well-tolerated, non-exercise-dependent test for detection and localisation of haemodynamically significant coronary artery stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Differentiation of single solid lesions in the lungs by means of single-photon emission tomography with technetium-99m methoxyisobutylisonitrile.

The value of technetium-99m methoxyisobutylisonitrile (MIBI) single-photon emission tomography (SPET) of the chest in differentiating lung carcinomas of various histological types and benign lesions was assessed in 54 patients (47 males and 7 females aged 19-77 years) with single solid lung masses. Chest radiography had indicated that 46 of the lesions were malignant (8 small cell carcinomas, 14 epidermoid carcinomas, 18 adenocarcinomas and 6 undifferentiated large cell carcinomas) and eight, benign. Ten, volunteers who also agreed to undergo 99mTc-MIBI SPET of the chest served as a control group. The results showed that only 65% (30/46) of the lung malignancies were detected by 99mTc-MIBI SPECT, including 63% (5/8) of the small cell carcinomas, 64% (9/14) of the epidermoid carcinomas, 72% (13/18) of the adenocarcinomas and 50% (3/6) of the undifferentiated large cell carcinomas. However, 75% (6/8) of the benign lesions were also detected. The diagnostic sensitivity, specificity and accuracy in differentiating malignant and benign lesions were 65%, 57% and 70%, respectively. We conclude that 99mTc-MIBI is of limited use in the differentiation of single solid lesions in the lungs.

The significance of a dipyridamole induced 99mTc-MIBI perfusion abnormality on single photon emission tomography: a quantitative validation with labelled water and positron emission tomography.

To relate technetium-99m 2-methoxy-isobutyl-isonitrile (99mTc-MIBI) uptake to regional myocardial blood flow (rMBF), 99mTc-MIBI single photon emission tomography (SPET) and H2(15)O positron emission tomography (PET) scans were obtained at rest and after dipyridamole infusion in six patients with single vessel coronary artery disease. 99mTc-MIBI and H2(15)O data sets were created for each segment perfused by the stenotic vessel and for a normal reference area, assigning regions on the SPET tomograms to comparable regions on the PET by similar transaxial image reconstructions. All patients demonstrated post-dipyridamole 99mTc-MIBI perfusion defects in the territories supplied by the stenotic arteries. Resting rMBF in these regions was slightly lower than that in the normal areas (0.82 +/- 0.05 vs 0.90 +/- 0.09 ml/g/min, P = NS). A 43% +/- 14% reduction in 99mTc-MIBI activity in the area at risk was coupled with on average a 60% +/- 9% reduction in post-dipyridamole rMBF compared with control regions (0.98 +/- 0.08 vs 2.52 +/- 0.51 ml/g/min, P < 0.001). Thus, SPET assessment of 99mTc-MIBI uptake tends to underestimate the perfusion contrast between areas with normal and areas with low coronary vasodilatory reserve when compared to PET. However, these findings may still not affect the clinical usefulness of 99mTc-MIBI and more extensive studies are required to confirm these results in the clinical environment.