Objective      To investigate the value of

99

Tc

m

-methoxyisobutylisonitrile (

99

Tc

m

-MIBI) SPECT/CT fusion imaging in assisting radiotherapy target positioning o

f lung cancer

and to analyze the relationship between the rate of

99

Tc

m

-MIBI uptake and chemotherapy efficacy in lung cancer.       Methods      In a retrospective study

99

Tc

m

-MIBI SPECT/CT were performed in 19 patients with non-small-cell lung cancer (NSCLC) within one week before radiotherapy and chemotherapy. The gross tumor volume was obtained by the region of interest (ROI) technique

and the planning target volume (PTV) was also identified. The radioactive counts of ROI were analyzed and early target/normal (T/NT

e

)

delayed target/normal (T/NT

d

) and retention index (RI%) were calculated. The association of T/NT

e

T/NT

d

and RI% with patients’ clinical stage and pathological type was analyzed.       Results      Among all the 19 NSCLC patients who underwent

99

Tc

m

-MIBI SPECT/CT

18 patients were positive. The PTVs of 15 patients obtained from CT were modified according to SPECT/CT

accounting for 78.9%. Of the 15 patients with modified PTVs

the tissues of atelectasis and tumor were clearly identified in 11 patients

accounting for 57.9%. The mean values of T/NT

e

and T/NT

d

of the good-response patients (2.47±0.23 and 2.35±0.19) were significantly higher than those of the poor-response patients (1.72±0.10 and 1.63±0.12， P0.01)

while RI% showed no significant difference between the two groups (P0.05). There were no significant differences of T/NT

e

T/NT

d

and RI% among the patients with different clinical stages and pathological types (P0.05).       Conclusion     

99

Tc

m

-MIBI SPECT/CT fusion imaging is helpful to optimize radiotherapy target. Using T/NT

e

2.0 as the threshold for assessing chemotherapy efficacy has high accuracy

and can avoid the interference from patients’ clinical stage and pathological type.