Diagnostic value of 123I-IMT SPECT in the follow-up of head and neck cancer.

BACKGROUND: Nuclear medicine imaging is increasingly used in the evaluation of tumors of the head and neck. In the current study, we assess the value of single-photon emission tomography (SPECT) using the amino acid tracer L-3-[123I]iodine-alpha-methyl-tyrosine (IMT) for the detection of recurrent head and neck cancer. PATIENTS AND METHODS: 45 consecutive patients with suspected recurrence of previously treated head and neck cancer were examined by IMT-SPECT using a dual head system with integrated low-dose computed tomography (CT). The accuracy of the IMT-SPECT was evaluated by correlating the findings with results of histology or clinical and CT/MRI (magnetic resonance imaging) follow-up examinations. RESULTS: The sensitivity, specificity and accuracy of IMT-SPECT in the detection of recurrent/persistent tumors were 83, 89 and 84.5%, respectively. The positive and negative predictive value amounted to 96.5 and 60%, respectively. CONCLUSION: IMT-SPECT using integrated low-dose CT appears to be a helpful complementary imaging tool for the detection of local recurrences and lymph node metastases of head and neck cancer and their differentiation from treatment-induced changes. The advantage of the method is the high positive predictive value in the diagnosis of relapsed tumors. However, a negative IMT-SPECT result does not exclude a recurrence.

Value of 123I-IMT SPECT for diagnosis of recurrent non-astrocytic intracranial tumours.

The value of single-photon emission tomography (SPECT) using iodine-123-alpha-methyl-tyrosine (IMT) for the diagnosis of recurrent or residual gliomas is well established. In the current study we investigated whether IMT-SPECT could also be useful in the follow-up of brain metastases and other intracranial tumours of non-astrocytic origin. The study included 22 patients with suspected recurrent intracranial tumours of non-astrocytic origin (12 brain metastases, one supratentorial primitive neuroendocrine tumour (PNET), one rhabdoid tumour, two clivus chordomas, three ependymomas, two pituitary tumours, one anaplastic meningioma) who had previously been treated by surgery and/or radio/chemotherapy. SPECT results were correlated with clinical and MRI follow-up data. The study was true positive in 13 patients, true negative in five, false positive in one and false negative in three patients. Notably, all false negative findings were <13 mm. The resulting sensitivity of the IMT-SPECT was 81%. We concluded that the IMT-SPECT is a promising complementary imaging tool for the detection of recurrences of non-astrocytic intracranial tumours and their distinguishing from treatment-induced changes. The limitation of the IMT-SPECT is its low sensitivity for the detection of small lesions.