Steven E. Harms

A physics-based coordinate transformation for 3-D image matching

Many image matching schemes are based on mapping coordinate locations, such as the locations of landmarks, in one image to corresponding locations in a second image. A new approach to this mapping (coordinate transformation), called the elastic body spline (EBS), is described. The spline is based on a physical model of a homogeneous, isotropic three-dimensional (3-D) elastic body. The model can approximate the way that some physical objects deform. The EBS as well as the affine transformation, the thin plate spline and the volume spline are used to match 3-D magnetic resonance images (MRIs) of the breast that are used in the diagnosis and evaluation of breast cancer. These coordinate transformations are evaluated with different types of deformations and different numbers of corresponding (paired) coordinate locations. In all but one of the cases considered, using the EBS yields more similar images than the other methods.

Changes in signs and symptoms following temporomandibular joint disc repositioning surgery

Fifty-one subjects with documented intra-articular pathology refractory to non-surgical therapy underwent temporomandibular joint (TMJ) disc repositioning surgery. Following surgery, subjects were evaluated for 6 months to 6 years by clinical examinations and questionnaires at designated times, and by postsurgical joint imaging. Significant decreases were noted in pain (headache, TMJ pain, ear pain, and neck/shoulder pain), the incidence of joint sounds and locking, and the presence of dietary restrictions. However, 35% of the subjects continued to have residual TMJ pain, and a similar percentage continued to need periodic nonsteroidal anti-inflammatory drugs for analgesia. Some degree of dietary restriction remained in approximately 50% of the subjects, and joint sounds persisted in a similar percentage following surgery. Mean mouth opening was improved by 8 mm, although lateral movements were increased by less than 0.5 mm. Surgery did not decrease the occurrence of jaw deviation, and disc position was unchanged in 86% of the joints imaged at an average of 2 years following surgery. Although TMJ disc repositioning surgery significantly improved pain and dysfunction in TMJ surgery patients, the improvement in disc position was not maintained in most subjects following surgery.

Arthroscopic TMJ surgery: effects on signs, symptoms, and disc position.

Nineteen subjects with documented intra-articular pathology refractory to nonsurgical therapies underwent temporomandibular joint (TMJ) arthroscopy involving lysis and lavage in the superior joint space. Following surgery, subjects were evaluated for 6 to 12 months by clinical examinations and questionnaires at designated time periods and by postsurgical joint imaging. Significant improvement was noted in pain, mandibular movement, and diet. No improvement was noted in the incidence of joint sounds, and disc position was unchanged in 80% of the joints. The findings suggest that disc repositioning may not be needed to achieve clinical success.

Magnetic resonance imaging: Techniques

Method for MR imaging of an object in which various RF and magnetic field gradient pulse sequences are used to produce transverse magnetization and to generate echoes. The RF pulse sequence may include a sinusoidal waveform component defined by either y=sin x, 0≦x ≦4π; y=cos x, 0≦x ≦4π; or y=sin x, 0≦x≦π/2, y=cos x, π/2≦x≦π; and a phase component defined by either y=0, 0≦x≦2π, y=π, 2π≦x≦4π; or y =-2πcos x, 0≦x≦π/2, y=-2πsin x, π/2≦x≦π. The selected waveform and phase components may be combined to form a first, composite RF signal and the Hilbert transform of the composite RF signal selected as a second RF signal. Alternately, the second RF pulse sequence may be comprised of first and second phase shifting linear ramps. The selected gradient magnetic field pulse sequences may include a first sinusoidal readout pulse sequence defined by y=ax sin x, 0≦x≦nπ and a second sinusoidal readout pulse sequence defined by y=ax cos x, 0≦x≦nπ, first and second constant magnitude phase encoding pulse sequences, or a square wave as a readout pulse sequence and a series of positive amplitude spikes positioned at each transition for the readout pulse sequence as a phase encode pulse sequence.

Diagnostic and therapeutic processes utilizing magnetic resonance imaging techniques

Method for diagnosing and treating tissue suspected of containing a lesion. A shaped pulse sequence is selected for each of waveform, phase and frequency components of an RF signal based upon characteristics of the tissue suspected of containing a lesion and an RF signal comprised of the selected waveform, amplitude and frequency shaped pulse sequences generated. A series of echoes is received in response to the generated RF signal and a real-time MR image of the tissue suspected of containing a lesion is produced using the series of received echoes. The tissue is then diagnostically evaluated for the presence of lesions using the produced real-time MR image. Using the produced real-time MR image of the tissue, boundaries between the tissue and each lesion detected during the evaluation of the tissue are determined and the lesion removed from the surrounding healthy tissue using a therapeutic delivery system while observing the boundary between the lesion and the surrounding healthy tissue using the produced real-time MR image.

MR evaluation of giant cell tumors of the tendon sheath

Giant cell tumor of the tendon sheath (GCTTS) is a benign condition that involves the synovium of the tendon sheaths. Histologically, GCTTS is similar to pigmented villonodular synovitis. The MRI findings in two cases of GCTTS are reported. In both cases, predominantly low signal is seen on T1-weighted, proton density weighted, and T2-weighted images. This information may be useful in distinguishing GCTTS from other mass lesions involving the tendon sheaths.

Three-dimensional MR imaging of the knee using surface coils.

The selective three-dimensional magnetic resonance imaging acquisition method is used to obtain thin (0.8 mm), contiguous slices of the knee. When combined with the improved signal-to-noise ratio of surface coils, this method produces excellent anatomical definition of the knee. Two fresh cadaver specimens were imaged and dissected. Normal anatomy was defined on three normal volunteers. Four patients with knee injuries were imaged. This method may be useful in the routine imaging of patients with certain traumatic knee injuries.

MR imaging of pseudoaneurysms in aortocoronary bypass graft.

Aneurysm formation may complicate aortocoronary saphenous vein bypass grafts. Because of multiplanar imaging capabilities and the potential for flow evaluation, magnetic resonance (MR) is useful as a noninvasive diagnostic technique. Two cases of pseudoaneurysm formation were evaluated by MR and demonstrate the clinical value of this modality.

Magnetic resonance imaging of the temporomandibular joint using a surface coil

Magnetic resonance imaging (MRI) was done in 454 temporomandibular joints of 240 patients and the images produced were correlated with arthrographic, tomographic, and, in the 85 patients who were operated on, surgical findings. The MRI was found to be more accurate than arthrography in demonstrating soft tissue changes. In addition, the technique does not expose the patient to ionizing radiation and has no known biological hazard.

Elastic body splines: a physics based approach to coordinate transformation in medical image matching

In a landmark based medical image matching scheme, a coordinate transformation maps a set of landmark locations in one image onto a corresponding set in a second image. A novel approach to this transformation, the elastic body spline, is introduced. The development of the spline is outlined. An example of using the spline to match 3D magnetic resonance images (MRIs) of the breast is described. The elastic body spline is compared to the thin plate spline and, for 3D breast MRIs, is found to have superior performance as assessed by several measures of the similarity of the matched images.<<ETX>>