| Purpose: In the workup of a solitary pulmonary lesion there is a clinical demand for noninvasive techniques that precisely diagnose whether the lesion is benign or malignant to instead of chest CT scan, fibro-bronchoscory, CT or B-Ultrasound guided percutanuous lung biopsy, thereby determining a rationale for treatment and reducing the number of unnecessary thoracotomies. There have been many attempts to use nuclear medicine procedures to overcome the limitations of morphological imaging such as chest CT or magnetic resonance imaging and the invasiveness of the thoracoscopy. The CT scan has been played an important role in diagnosing and staging lung cancer. However, CT has several limitations, including a limited ability to distinguish between benign and malignant tumors especially the diameter less than 3cm. Bronchoscopy is a traumatic procedure and has a limited to some patients who has some severe diseases such as cardio-pulmonary insufficiency; Sputum cytology has high specificity but low sensitivity, openning lung biopsy has high sensitive and specific, buthas limited to use by traumatic and too expensive.In 1987, American scholar Dr. Muller found abnormal accumulation of "Tc-MIBI ( hexakis 2-methoxy isobutyl isonitrile) in a patient's metastasis lung cancer from post-operation of thyroid cancer while detecting a cardiac imaging with "Tc-MIBI, and was obtained extensive intension in the world, hi 1988, Hassan reported that "Tc-MIBI has the characteristic of intimate to cancer and studied the uptake of "Tc-MIBI in the malignant cell. After that, as a cancer positive imaging indicator, "Tc-MIBI and 201T1 were intensive evaluated for the patients with primary and metastasis lesion of nasopharyngeal carcinoma, breast cancer, cerebral tumors, thyroid carcinoma, acquired high sensitivity and specificity. However, use of dual-isotope SPECT imaging in solitary lung lesion has been little reported. This study is undertaken to evaluate whether "Tc-MIBI and 20IT1 dual-isotope SPECT imaging is useful in the differentiation of a solitary pulmonary lesion. We detected the uptake of "Tc-MIBI and 201T1 both hi the lesion and contralateral normal lung tissue and performed quantitative analysis of the abnormal uptake by drawing identical regions of interest, measured the mean regions of interest values and the ratios of lesion to normal lung uptake ratio (T/N ratio), these parameters were compared with histology and size.PatientsThere were 34 patients who were the first time found solitary lung lesion and not received radiotherapy or chemotherapy before, and no severe diseases, divided into two groups:1. Group lung cancer: 22 patients (18 men and 4 women, age range 29-77yr) including 12 with squamous cell carcinomas, 8 with adenocarcinoma, 2 with small cell carcinomas. Diagnosis was made by histopathological samples from bronchoscopy, CTor B-Ultrasound guided lung biopsy or lobectomy.2. Group Benign lesions: 12 patients (7 men and 5 women, age range 28-79yrs) including 6 with pneumonia, 5 with pulmonary tuberculosis and 1 with lung abscess. Diagnosis was made by bacteria analysis of sputum, histopathological sample from bronchoscopy or followed-up with antibiotics and antituberculosis therapy.Materials and Methods"mTc-MIBI is provided by Jiangshu Atomic energy institute and 201T1 by Shanghai Kexing Company. All the patients were underwent simultaneous dual-isotope SPECT imaging with high resolution and parallel hole collimator. A dose of 740Mbq of 99mTc-MIBI and 185MBq of 201T1 were injected peripheral intravenously. Early SPECT acquisition was performed 10 min and the delayed images acquired 2 hrs after injection. 64 projections were obtained using 128X 128 matrix and rotating 360 ?for 20 sec per view. Two energy analyzers were used for acquisition, which were set at 71KeV with a 15% window for 201T1 images, 140KeV with a 15% window for 99mTc. These projection data were processed with a two-dimensional low-pass filter and then corrected for the contamination scatter. Image reconstruct...
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