At present also radionuclide methods are used to diagnose pulmonary malignancies. One of them is solitary pulmonary nodule (SPN) scintigraphy using 99mTc-depreotide. 99mTc-depreotide is a somatostatin analogue with affinity to 3 out of 5 subtypes of somatostatin receptors.
Aim of the study: was to confirmed the usefulness of 99mTc-depreotide in detecting malignancy in SPN; finding lymph nodes metastases; and overlapping scintigraphic scans and CT in precise localizsation of malignancy and its lymph nodes metastases.
Material and methods: The group studied comprised 50 patients with radiologically diagnosed SPN. Forty patients had a high resolution CT scan done with a GE Light Speed equipment-device. The acquired CT scans were sent via LAN (Local Area Network) to an ARPACS server in the Department of Nuclear Medicine, and thence to a Hermes Nuclear Diagnostics workstation. CT examinations were followed by scintigraphy with 99mTc-depreotide.
Results: In 32 patients 99mTc-depreotide was found to have accumulated excessively in SPN: in 23 cases malignancy was found, in the 9 remaining cases they were other abnormalities. In the 23 lung cancer patients, 99mTc-depreotide was found in 24 foci, including 18 in the mediastinum and axillary region. CT revealed affected lymph nodes only in 7 cases. The calculated sensitivity, specificity and accuracy in SPN were 89%, 60%, 82%, respectively. The tumour/background index in malignancies confirmed histologically was 2.58 +/- 0.89. Where lymph nodes metastases were suspected in the diagnosed malignancies, the lymph node/background index was 2.60 +/- 0.85. In 25 cases lesion localization was more accurate when scans were overlapped.
Conclusions: 99mTc-depreotide based examination is a sensitive method in the evaluation of SPN malignancy. Overlapping SPECT and CT scans in diagnosing SPN enables both pathological and physiological changes to be localized precisely. This method seems particularly valuable in imaging lymph nodes where metastases are suspected, especially when CT scans revealed no abnormalities.