Fluorine-18 fluoromisonidazole tumour to muscle retention ratio for the detection of hypoxia in nasopharyngeal carcinoma

Abstract

In vivo demonstration of hypoxia is of significance for tumour patient management. Fluorine-18 fluoromisonidazole ([18F]FMISO) is a proven hypoxic imaging agent. We developed an [18F]FMISO tumour to muscle retention ratio (TMRR) for the detection of tumour hypoxia in nasopharyngeal carcinoma (NPC). Data were acquired by positron emission tomography (PET) of the nasopharynx and neck after intravenous injection of 370 MBq of [18F]FMISO. Two imaging protocols were adopted: a long protocol for comprehensive dynamic information and a short protocol for a simple, clinically convenient imaging procedure. Tomograms were reconstructed and evaluated visually. ROI analysis on the basis of time-activity curve evaluation was performed to calculate the TMRR of NPC or cervical nodal metastases (CNMs) in relation to the suboccipital muscles at 2 h. The calculation of the TMRR was exactly the same for both the long and the short protocol as two 30-min composite frames had been created immediately after intravenous injection and 2 h after injection of [18F]FMISO in the long protocol. The normal tissue to muscle retention ratio (NTMRR) was derived similarly from the normal nasopharynx. The data of 12 controls and 24 patients with NPC were analysed. The long protocol was used in 15 patients, and the short protocol in nine. In controls, the mean NTMRR+/-1 SD was 0.96+/-0.14. The mean TMRRs for NPC and CNMs were 2.56+/-1.50 and 1.35+/-0.51, respectively; these values were significantly higher than the mean NTMRR for normal controls (P<0.005 in each case). At the retention threshold value of 1.24, tumour hypoxia occurred in 100% of the primary lesions of NPC and 58% of CNMs. The TMRR for undifferentiated carcinoma was significantly lower than that for non-keratinized carcinoma (P<0.05). The [18F]FMISO TMRR is a simple and clinically useful index for detecting tumour hypoxia in NPC.

18F-Fluoromisonidazole PET/CT: A Potential Tool for Predicting Primary Endocrine Therapy Resistance in Breast Cancer

“…Each tumor may have its own cutoff threshold because blood supply, location, and extent of necrosis vary from tumor to tumor. For example, 1.2 is a cutoff value for head and neck cancer and soft-tissue sarcomas (18,27,28), 1.24 is a cutoff value for nasopharyngeal carcinoma (29), and 1.4 is the cutoff for NSCLC because the unique structure of the lung parenchyma, including its dual blood supply and abundant oxygen-containing air space, may play a role in NSCLC's being less hypoxic than other tumor types (30,31). In our study, 16 patients with 33 lesions underwent hypoxia detection at baseline, which was then used to predict endocrine therapy outcome.…”

Positron emission tomography to assess hypoxia and perfusion in lung cancer

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The fate of hypoxic tissue on18F-fluoromisonidazole positron emission tomography after ischemic stroke

“…The minimum 2-hour time delay between injection and imaging is needed to allow tracer accumulation in hypoxic tissue and to ensure the development of sufficient contrast in activity between normal and hypoxic tissue. [15][16][17] The time of tracer injection was used to calculate the interval from stroke onset to PET study.…”