The substantia nigra in Parkinson disease: proton density-weighted spin-echo and fast short inversion time inversion-recovery MR findings.

BACKGROUND AND PURPOSE: A reduction in the area of the substantia nigra (SN) has been shown in patients with Parkinson disease. The substantia nigra is anteroinferolateral to the red nucleus, and it is important to precisely locate its true anatomic location to accurately measure SN area. Our purpose was to determine the exact location of the substantia nigra by correlating imaging and anatomic findings. We also attempted to quantitate SN area in patients with Parkinson disease compared with that in healthy control subjects on the basis of proton density-weighted spin-echo (SE) and fast short inversion time inversion-recovery (STIR) MR imaging findings. METHODS: In four healthy volunteers, dual-echo SE and fast STIR MR images were obtained in three orthogonal planes and an oblique coronal plane. These images were correlated with anatomic specimens to determine the location of the SN. The area of the SN was also measured on oblique coronal fast STIR images obtained at a plane perpendicular to the SN in 22 patients with Parkinson disease and in 22 age- and sex-matched healthy volunteers. RESULTS: The true anatomic location of the SN, anteroinferolateral to the red nucleus, was accurately identified, not on T2-weighted images, but on proton density-weighted SE images and fast STIR images as an area of hyperintense gray matter. The hypointense area seen on T2-weighted images corresponded to the anterosuperior aspect of the SN and to the adjacent crus cerebri. No statistically significant differences were noted in the size of the SN when the oblique coronal images of patients with Parkinson disease were compared with those of the control groups. CONCLUSION: The SN is located mainly beneath the red nucleus. Its location cannot be determined on the basis of T2-weighted imaging results but rather on the basis of proton density-weighted SE or fast STIR findings. SN volume loss is not found in Parkinson disease, and this finding is compatible with that of recent pathology reports in the literature.

Failure in presumption of residual disease by quantification of FDG uptake in esophageal squamous cell carcinoma immediately after radiotherapy.

To assess whether differentiation is possible between residual disease and complete response, 18F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography was performed in 17 cases of primary squamous cell carcinoma of the thoracic esophagus before (five control cases) or immediately after full-dose irradiation (12 treated cases). The FDG counts in the esophageal tumors were corrected by the dose of injected isotope and the weight of the patient, to produce a standardized uptake value (SUV). Endoscopy for post-treatment evaluation showed almost complete clearance of the tumor in seven treated cases (good-responders) and apparent residual tumor in the other five cases (poor-responders). There was a significant difference in the average median SUV between the controls and the treated (8.1 +/- 1.6 vs. 3.3 +/- 1.1), and between the poor-responders and good-responders (4.1 +/- 0.8 vs. 2.7 +/- 0.9). Three of the good-responders showed locoregional recurrence after four, six, and 18 months. Among the good-responders, the SUV of the cases of local recurrence was not inevitably higher than that of the others. The rate of FDG uptake in irradiated esophageal cancer approximately represents tumor response to radiotherapy, but it seemed impossible to differentiate residual disease from complete response.

Combining time-resolved and single-phase 3D techniques in contrast-enhanced carotid MR angiography.

We established an easy-to-use technique for performing contrast-enhanced carotid MR angiography (MRA) with a commercial scanner. Twenty-three patients with suspected carotid or vertebral arterial lesions were prospectively studied. Two techniques were applied in the study. After performing sagittal time-resolved acquisitions, we undertook a coronal single-phase 3D acquisition, in which the injection timing was estimated from the preceding images. In each case, we obtained multidirectional images with sufficient venous suppression. The combined use of time-resolved and single-phase 3D MRA is a feasible technique for obtaining selective arterial images without the use of special applications or hardware.