Evaluation of radiotherapeutic response in non-small cell lung cancer patients by technetium-99m MIBT and thallium-201 chloride SPET

Abstract

The purpose of this study was to investigate the relationship between technetium-99m hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) accumulation in tumours and response to radiotherapy in non-small cell lung cancer patients in comparison with the findings obtained using thallium-201 chloride (201Tl). Simultaneous dual single-photon emission tomography (SPET) imaging with 600 MBq 99mTc-MIBI and 111 MBq 201Tl was performed in 31 patients with biopsy- or sputum cytology-proven lung cancer. SPET images were acquired 15 min (early) and 2 h (delayed) after injection, and the early ratio, delayed ratio and retention index were measured. The tumours were classified into two groups on the basis of follow-up computed tomography (CT): responders (at least 50% reduction in tumour size) and non-responders (little or no change in tumour size). The mean (+/-SD) values of early ratio, delayed ratio and retention index using 99mTc-MIBI SPET were 3.0+/-1.1, 2.7+/-1.0 and -9.5+/-12.7, respectively, in responders and 2.4+/-0.7, 2.0+/-0.5 and -18.4+/-9.0, respectively, in non-responders. The corresponding values using 201Tl chloride SPET were 3.7+/-1.0, 4.7+/-1.5 and 24.2+/-22.1 in responders and 3.3+/-1.2, 4.0+/-1.3 and 20.4+/-20.5 in nonresponders. Using 99mTc-MIBI, the delayed ratio and retention index in responders were significantly higher than those in non-responders (P<0.01 and P<0.05, respectively). The results of this study indicate that patients with higher delayed ratio and retention index values using 99mTc-MIBI SPET are likely to respond better to radiotherapy than those with lower values. 99mTc-MIBI SPET may give an indication of the short-term response to radiotherapy in patients with non-small cell lung cancer.

Hypoxia-induced alteration of tracer accumulation in cultured cancer cells and xenografts in mice: implications for pre-therapeutic prediction of treatment outcomes with 99mTc-sestamibi, 201Tl chloride and 99mTc-HL91

“…Previous reports concerning pre-therapeutic scintigraphic prediction of tumour response to treatment have suggested that poor responders will exhibit less intense accumulation of 99m Tc-MIBI than good responders [8,9,10,11,12,13,14,15,16]. Given these observations, we hypothesized that hypoxic conditions would interfere with the accumulation of 99m Tc-MIBI in tumour cells.…”

“…Subsequently, one of the 99m Tc compounds was introduced to the medium at 2×10 6 cells/370 kBq/ml after achieving equilibrium of oxygen tension measured with O 2 microelectrodes (MT Giken, Tokyo, Japan). 201 Tl chloride (Nihon Medi-physics, Nishinomiya, Japan) was simultaneously added as a comparison at 185 kBq/ml because this tracer is often used in the diagnosis of various malignant lesions [1,5,6,11,13,14]. Total incubation volume was 5 ml.…”

“…Furthermore, 99m Tc-MIBI has been used to monitor lesion response during and at the conclusion of treatments such as radiotherapy and chemotherapy [5,6,7,8]: lesions showing a favourable response demonstrated a reduction of tracer accumulation due to the treatment. More interestingly, 99m Tc-MIBI scintigraphy may enable pre-therapeutic prediction of treatment outcomes [8,9,10,11,12,13,14,15,16]. A number of studies have been conducted regarding small cell and non-small cell lung cancer [8,9,10,11,12,13,14], malignant lymphoma [15] and breast cancer [16].…”

“…More interestingly, 99m Tc-MIBI scintigraphy may enable pre-therapeutic prediction of treatment outcomes [8,9,10,11,12,13,14,15,16]. A number of studies have been conducted regarding small cell and non-small cell lung cancer [8,9,10,11,12,13,14], malignant lymphoma [15] and breast cancer [16]. In general, these reports have suggested that tumours exhibiting weak tracer uptake do not respond to treatment, whereas those displaying intense uptake respond well.…”

Bone single photon emission computed tomography (SPECT) in a patient with Pancoast tumor: a case report

“…13,14 Furthermore, it has been shown that Tc-99m methoxy isobutyl isonitrile (MIBI) SPECT faithfully identifies not only the mediastinal lymph node metastases in patients with NSCLCs, 15 but also the chemotherapy response in both small-cell lung carcinoma (SCLC) 16 and NSCLCs. 17 The functional imaging mode of SPECT has a capability to visualize and measure molecular processes in vivo. However, it suffers from low spatial resolution, in comparison with CT or MRI.…”