Value of retrospective image fusion of ¹8F-FDG PET and MRI for preoperative staging of head and neck cancer: comparison with PET/CT and contrast-enhanced neck MRI.

PURPOSE: To assess the clinical value of retrospective image fusion of neck MRI and (18)F-fluorodeoxyglucose ((18)F-FDG) PET for locoregional extension and nodal staging of neck cancer. MATERIALS AND METHODS: Thirty patients with carcinoma of the oral cavity or hypopharynx underwent PET/CT and contrast-enhanced neck MRI for initial staging before surgery including primary tumor resection and neck dissection. Diagnostic performance of PET/CT, MRI, and retrospective image fusion of PET and MRI (fused PET/MRI) for assessment of the extent of the primary tumor (T stage) and metastasis to regional lymph nodes (N stage) was evaluated. RESULTS: Accuracy for T status was 87% for fused PET/MRI and 90% for MRI, thus proving significantly superior to PET/CT, which had an accuracy of 67% (p=0.041 and p=0.023, respectively). Accuracy for N status was 77% for both fused PET/MRI and PET/CT, being superior to MRI, which had an accuracy of 63%, although the difference was not significant (p=0.13). On a per-level basis, the sensitivity, specificity and accuracy for detection of nodal metastasis were 77%, 96% and 93% for both fused PET/MRI and PET/CT, compared with 49%, 99% and 91% for MRI, respectively. The differences for sensitivity (p=0.0026) and accuracy (p=0.041) were significant. CONCLUSION: Fused PET/MRI combining the individual advantages of MRI and PET is a valuable technique for assessment of staging neck cancer.

¹8F-FDG-PET/CT findings of retroperitoneal tumors: a pictorial essay.

A variety of different tumors can arise from any of the tissues present in the retroperitoneum, and they exhibit a wide range of pathologic types. Although computed tomography (CT) and magnetic resonance imaging (MRI) can demonstrate important characteristics of these tumors, diagnosis is often challenging for radiologists. The purpose of this pictorial essay is to review (18)F-fluorodeoxyglucose positron emission tomography/CT (FDG-PET/CT) features of different kinds of benign and malignant retroperitoneal tumors in comparison with CT or MRI findings alone and to become familiar with the wide variety of imaging characteristics.

Tractography for arteriovenous malformations near the sensorimotor cortices.

We sought to use diffusion-tensor imaging-based tractography to assess the relationship between the arteriovenous malformations (AVM) and the sensorimotor cortices/tracts. Three patients who had an AVM closely situated to the sensorimotor tracts were studied. The relationship between the sensorimotor tracts and the AVM was well demonstrated in all patients. Tractography was also helpful in identifying the location of the motor cortex in some of the cases.

Stroke patients' evolving symptoms assessed by tractography.

PURPOSE: To test the hypothesis that an interval evolution in the location of the depicted sensorimotor tract relative to the infarct (the "tract-infarct relationship") may be related to stroke victims' symptom progression. MATERIALS AND METHODS: Patients (N = 7) who underwent multiple diffusion-tensor imaging (DTI) studies during symptomatic progression were included in this study. DTI was performed using a single-shot echo-planar imaging (EPI) technique with a motion-probing gradient in six orientations, a b-value of 800 seconds/mm2, and six image averages. The total scan time was four minutes and 24 seconds. Fiber-tracking of the sensorimotor pathways was performed, and the locations of these tracts were retrospectively assessed in relation to the evolution of the symptoms. RESULTS: Five of the seven patients showed an interval enlargement of the infarct on diffusion-weighted (DW) images. In two of these cases the lesion enlarged to involve the sensorimotor tracts, while in three cases the lesion enlarged only so far to come into close proximity to the sensorimotor tract. In the remaining two cases there was no interval enlargement of the infarct, and therefore the tract-infarct relationship could not account for the evolution of the symptoms in these cases. CONCLUSION: A tract-infarct relationship can be observed with the use of a fiber-tracking technique, and the results may improve our understanding of the symptom progression seen in stroke victims.