Functional Retention of Tc-99m MIBI in Mediastinal Lymphomas As a Predictor of Chemotherapeutic Response Demonstrated by Consecutive Thoracic SPECT Imaging

Abstract

Tc-99m MIBI is used as a tumor imaging agent and has been proposed to measure p-glycoprotein function, which plays an important role in tumor multidrug resistance to chemotherapy. It has been reported that lung cancer and breast cancer with a high retention of Tc-99m MIBI have been more responsive to chemotherapy than tumors with low retention. Thus Tc-99m MIBI SPECT could be used as a measure of p glycoprotein function and consequently may serve as a predictor of the tumor's responsiveness to chemotherapeutic agents. Described here are two patients with lymphomas, one with non-Hodgkin's lymphoma and the other with Hodgkin's disease, who underwent Tc-99m MIBI thoracic SPECT before and after chemotherapy. The sequential studies demonstrated a reduction in tumor size and diminished tumor uptake in one patient and disappearance of tumor uptake after a course of chemotherapy in the other patient. The data suggest that elevated Tc-99m MIBI uptake in a tumor as a result of retention by p glycoprotein not only demonstrates mediastinal involvement of lymphomas but also may be used to forecast responsiveness to chemotherapy.

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.…”

“…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.…”

Oncologic Applications of Sestamibi: In Vivo Imaging of Multi-Drug Resistance

“…99m Tc-Sestamibi scan represents P-gp expression more accurately than other prognostic factors and is able to predict the chemotherapy response in malignant lymphomas [14,[78][79][80][81][82]. In fact, 99m…”

<SUP>99m</SUP>Tc-Tetrofosmin for Functional Imaging of P-glycoprotein Modulation In Vivo

“…[38][39][40] Of this list of radiolabeled drugs, only 11 C-daunorubicin and 11 C-verapamil have been used to any significant extent. [54][55][56][57][58][59] Sestamibi is now being used to monitor the effectiveness of Pgp modulator regimens. 41 Increased levels of tracer in the brain were noted in mice treated with cyclosporin A and in mice in which the mdr1 gene had been knocked out.…”