Magnetic resonance imaging: comparison of four pulse sequences in assessing primary bone tumours

Significance of Frequency-Selective Fat Saturation T2-Weighted MR Images for the Detection of Bone Marrow Edema in the Mandibular Condyle

The objective of this study was to evaluate the utility of frequency-selective fat saturation (FS) T2-weighted images (T2WI) for the detection of bone marrow edema in the mandibular condyle. MR evidence of bone marrow abnormalities was examined on the set of FS T2WI and conventional T1WI or of conventional T2WI and T1WI in 200 patients with temporomandibular joint (TMJ) related pain. Other parameters studied were TMJ effusion, disk displacement categories, and cortical bone abnormalities. The detection rate and area of bone marrow edema by FS T2WI and T1WI were significantly greater than those assessed by conventional T2WI and T1WI. The correlation between bone marrow abnormalities on FS T2WI and T1WI and pain was significantly stronger than with conventional T2WI and T1WI. This study confirms that FS T2WI is useful for the detection of the "edema pattern" in the mandibular condylar associated with TMJ-related pain.

Instability of background fat intensity suppression using fat-saturated (FS) MR imaging techniques according to region and reconstruction procedure in patients with oral cancer

The purpose of the present study is to evaluate the background fat intensity suppression instability of each area in the head and neck region, and in the post-reconstruction with metal plate and myocutaneous flap, of patients with oral cancer using fat-saturated (FS) images. STIR and FS T2-weighted images at pre- and post-surgery in 59 patients with oral cancer were scored for uniformity of fat suppression and tissue conspicuity in each region of the head and neck. The scores of FS on uniformity of fat suppression pre-operatively were worse than those of STIR in the mandibular level, but not lesion and tissue conspicuity. However, the deterioration both of scores between pre- and post-surgery using FS was worse than that using STIR using metal plate and/or myocutaneous flap. At diagnosis, we should recognize on MR images using FS that instability of the status of fat suppression might be brought about by respective area and reconstruction with metal plate and myocutaneous flap of patients with oral cancer.

Magnetic resonance imaging in reflex sympathetic dystrophy syndrome of the foot

OBJECTIVE

The purpose was to analyze magnetic resonance imaging (MRI) abnormalities in reflex sympathetic dystrophy syndrome (RSDS) of the foot, with the goal of helping to meet the difficult diagnostic challenges raised by this condition.

METHODS

Retrospective study of 20 patients with RSDS of the foot, 15 at the warm phase and five at the dystrophic phase.

RESULTS

Of the 15 patients at the warm phase, seven had evidence of bone edema (low signal on T1-weighted images and high signal on T2, T2 STIR, and fat saturation images) and five had occult fractures (linear band of low signal on T1 and T2 weighted images with no enhancement after contrast injection). Other abnormalities included soft tissue changes in three patients, joint effusion in five, and synovial hypertrophy in one. Of the five patients at the dystrophic phase, one had a fracture with a joint effusion, one had isolated joint edema, and three had normal MRI findings.

CONCLUSION

Bone marrow edema is inconsistent at the warm phase of RSDS and is never present at the dystrophic phase. Thus, absence of bone edema does not rule out RSDS. Fractures may be visible by MRI in one-third of patients with RSDS and no clinical or plain radiography evidence of fracturing.

The use of MRI in the diagnosis of benign and malignant bone and soft tissue tumours

Two hundred and thirty four suspected primary bone and soft tissue tumours were investigated using plain films and MRI. The MR appearance of 200 of these tumours was assessed with respect to the intensity of the lesion, the homogeneity of the tumour, the presence or absence of a capsule or lobulation, whether the tumour was whorled or not and whether it contained either fluid or blood. Apart from benign lipomas and some malignant myxoid liposarcomas, however, it seemed virtually impossible to tell one tumour from another and in many cases to differentiate a benign lesion from a malignant tumour using MRI alone. We recommend that the workup of a suspected soft tissue tumour should be initially by MR scanning and that the workup of a suspected malignant bone tumour should be plain films followed by an MRI scan.