Image fusion of thallium-201 SPECT and MR imaging for the assessment of recurrent head and neck tumors following flap reconstructive surgery

Surveillance Imaging Following Head and Neck Cancer Treatment and Microvascular Reconstruction

OBJECTIVES/HYPOTHESIS

To assess the accuracy and utility of positron emission tomography/computed tomography (PET/CT) compared with magnetic resonance imaging (MRI) for detecting head and neck cancer (HNC) recurrence after microvascular reconstructive surgery.

STUDY DESIGN

Retrospective cohort study.

METHODS

Analysis of HNC patients who underwent microvascular reconstruction at a single, tertiary academic center following ablative surgery from 1998 to 2015. Forty-six patients aged 61.4 ± 15.8 years with both PET/CT and MRI examinations were identified. Two radiologists were blinded and interpreted each imaging study. Recurrence certainty scores were determined via continuous (0-100) and Likert ("Likely" to "Unlikely") scales, with larger values indicating a higher likelihood of recurrence. Pathologic confirmation of recurrence was confirmed in 23 patients (50%).

RESULTS

Among those with primary site recurrences, mean recurrence certainty was significantly higher with PET/CT versus MRI on the continuous scale (63.9 vs. 44.4, P = .006). A receiver operating characteristic analysis for predicting primary site recurrence demonstrated a significantly larger area under the curve of 0.79 for PET/CT compared to 0.64 for MRI (P = .044). Categorization of "Likely" primary site recurrence on PET/CT, versus MRI, had higher sensitivity (0.63 vs. 0.40), but lower specificity (0.90 vs. 1.0). MRI demonstrated higher sensitivity (1.0 vs. 0.78) at detecting regional site recurrences.

CONCLUSION

PET/CT demonstrates greater sensitivity than MRI as a surveillance tool for primary site recurrence following microvascular reconstruction where clinical evaluation is hindered by anatomical distortion. Therefore, PET/CT should be pursued as first-line imaging, with MRI utilized for confirmation of positive imaging findings at the primary site.

LEVEL OF EVIDENCE

2 Laryngoscope, 2021.

Correlating molecular character of NIR imaging agents with tissue-specific uptake

Near-infrared (NIR) fluorescent contrast agents are emerging in optical imaging as sensitive, cost-effective, and nonharmful alternatives to current agents that emit harmful ionizing radiation. Developing spectrally distinct NIR fluorophores to visualize sensitive vital tissues to selectively avoid them during surgical resection of diseased tissue is of great significance. Herein, we report the synthetic variation of pentamethine cyanine fluorophores with modifications of physicochemical properties toward prompting tissue-specific uptake into sensitive tissues (i.e., endocrine glands). Tissue-specific targeting and biodistribution studies revealed localization of contrast agents in the adrenal and pituitary glands, pancreas, and lymph nodes with dependence on molecular characteristics. Incorporation of hydrophobic heterocyclic rings, alkyl groups, and halogens allowed a fine-tuning capability to the hydrophobic character and dipole moment for observing perturbation in biological activity in response to minor structural alterations. These NIR contrast agents have potential for clinical translation for intraoperative imaging in the delineation of delicate glands.

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.

Combined SPECT/CT imaging using 123I-IMT in the detection of recurrent or persistent head and neck cancer

The aim of the study was to assess the clinical value of combined SPECT/CT imaging using L: -3-[123I]iodine-alpha-methyl tyrosine (IMT) for the differential diagnosis of recurrences in patients pre-treated for head and neck cancer. Thirty-four consecutive patients with biopsy-proven carcinomas, who had previously been treated by surgery and/or radio/chemotherapy, were examined at our clinic by IMT-SPECT using a dual-head system with integrated low-dose CT. SPECT results were correlated with histopathology, clinical and CT/MRI follow-up data. In the follow-up after SPECT examination, the final diagnosis of recurrent tumour was established in 26 patients; the remaining eight patients were recurrence-free (follow-up >6 months). IMT-SPECT/CT correctly detected recurrent disease and/or neck lymph node metastases in 22 patients. In addition, distant metastases were displayed in two patients. The study was false-negative in four patients (sensitivity 85%). True-negative results were registered in seven patients, and false-positive in one patient. Image fusion with coregistered low-dose CT facilitates the localisation and interpretation of IMT-SPECT findings. IMT-SPECT using integrated low-dose CT is a promising non-invasive imaging tool for the detection of head and neck cancer recurrences and their differentiation from treatment-induced changes.

Value of image fusion using single photon emission computed tomography with integrated low dose computed tomography in comparison with a retrospective voxel-based method in neuroendocrine tumours

The objective was the evaluation of single photon emission computed tomography (SPECT) with integrated low dose computed tomography (CT) in comparison with a retrospective fusion of SPECT and high-resolution CT and a side-by-side analysis for lesion localisation in patients with neuroendocrine tumours. Twenty-seven patients were examined by multidetector CT. Additionally, as part of somatostatin receptor scintigraphy (SRS), an integrated SPECT-CT was performed. SPECT and CT data were fused using software with a registration algorithm based on normalised mutual information. The reliability of the topographic assignment of lesions in SPECT-CT, retrospective fusion and side-by-side analysis was evaluated by two blinded readers. Two patients were not enrolled in the final analysis because of misregistrations in the retrospective fusion. Eighty-seven foci were included in the analysis. For the anatomical assignment of foci, SPECT-CT and retrospective fusion revealed overall accuracies of 91 and 94% (side-by-side analysis 86%). The correct identification of foci as lymph node manifestations (n=25) was more accurate by retrospective fusion (88%) than from SPECT-CT images (76%) or by side-by-side analysis (60%). Both modalities of image fusion appear to be well suited for the localisation of SRS foci and are superior to side-by-side analysis of non-fused images especially concerning lymph node manifestations.