Sonographic Scans of Maxillofacial Osteonecrosis
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Sonographic image through the jaw shows only a small area of missing or dry marrow.

The Maxillofacial Center, 165 Scott Avenue, Suite 100, Morgantown, WV 26508 USA
Phone: 304-292-4429   Fax: 304-291-5149    Email: MFC@aol.com

Sonographic Scans

A new technique is available to find diseased bone and bone marrow with the use of ultrasound, whether that disease is from infection or ischemic damage.  It does not use the standard ultrasound technique of interpreting scatter or background (reflected) sonic signals, but rather picks up residual sonic waves after the sound has traveled completely through the bone.  This technique is based on the fact that sound travels faster through water (or the liquefied fat in fat cells) or moist tissues than dry tissues or air, and so is ideal for a disease such as osteonecrosis with its many hollow, air-filled spaces and its dry bone and fibrous marrow.

Sonography of the jaws is accomplished by the use of a stand-alone computerized sound generating and sensing machine, the CAVITAT™, which is now commercially available  (CAVITAT™Medical Technologies, 5768 S. Malta St., Aurora, CO 80015; phone: 303-693-5019).  The sound is sent through the bone via a customized ultrasonic transducer placed on the facial skin over the alveolar bone, it can be safely held in place by the doctor or the patient.  A digitized sensor screen is placed on the lingual surface of the alveolar bone.  A computer connected to the screen interprets the speed and strength of the generated sound after it has passed through the bone, converting the signal into a three-dimensional image representing a 1/2 inch square of alveolar bone (Figures 1 & 2). The image is color coded to distinguish the intensity of destruction (disease? damage? desiccation?), with normal bone represented by dark green and increasingly damaged bone represented by: light green, yellow/green, yellow (moderate loss), brown, brown/red, and red (most severe disease).  Additionally, sound traveling through normal, moist bone and marrow (and teeth roots) is represented by a tall column, while increasingly slow or weak signals are represented by increasingly short columns.  Each 1/2 inch square has 64 columns. The CAVITAT™ image can also be viewed in two dimensions and the image can be rotated at will on the computer screen.  The image can be printed out as a form which also includes patient demographics.

The image interpretation requires a certain amount of skill and placement of the sensor and transducer is very important, hence, this is something of a user-sensitive technique, but with careful use it appears to be a valuable adjunct to radiographic interpretation in the dental office.  The next generation machine is being designed to move along adjacent sites and create a collage image which may eventually be superimposed onto a patient's pantograph by lining up appropriate anatomic markers.

Initial animal studies proved the safety of the machine and were even successful in finding a few intraosseous cavitations (Figure 3) because by luck the jaws evaluated were from pigs.  Pigs have long been one of the major animal models for osteonecrosis of the hip, where that disease most often occurs.  Investigation with large numbers of humans has further demonstrated safety and appears to have also shown the machine's effectiveness in identifying even small marrow defects in the jaws, whether they are produced by dental infections (periapical lesions) or ischemic damage.  Ongoing research is attempting to analyze this and other features of the Cavitat, including a cadaver study of mandibles, comparing radiographic, gross and ultrasonic alterations (Figure 4). 

The idea to use a customized ultrasonic sound generator to find alveolar bone marrow defects in patients with minimal or no evidence of change on routine periapical and panographic dental radiographs was conceived by an ultrasonic engineer  in Colorado who suffered from an extremely severe, debilitating osteonecrosis of multiple sites of his jawbones.  His was not, however, a pain-producing case of maxillofacial osteonecrosis, but was associated instead with extreme fatigue, a very common "side effect" of such lesions.  The exact relationship between chronic fatigue and osteonecrosis is unclear.  There may be a common underlying disease process, such as a coagulation disorder, or it may be a consequence of the release of locally generated toxins or anti-myelin antibodies into the systemic circulation, or perhaps a consequence of a completely unknown process.  Be that as it may, the symptoms dramatically improved for this engineer once his diseased marrow was removed.

Sonographic Scans of Maxillofacial Osteonecrosis.

Click to Enlarge or Return to Text		Sonographic Feature
	[Return to text]	Figure 1: Small intramedullary cavitation. Area of missing or dry rotted bone is obvious.  Image is color coded to distinguish the intensity of destruction (brown = great loss of bone, yellow = moderate loss, dark green = no loss).
	[Return to text]	Figure 2: Large Intramedullary Cavitation. This was an area of completely hollow marrow which showed only subtle radiographic changes on routine dental x-rays.
	[Return to text]	Figure 3: Cavitations found in pig jaw during safety testing of Cavitat (first generation machine).
	[Return to text]	Figure 4: Cadaver examples.  A photo album of gross, radiographic and ultrasonic (sonographic) changes in cadaver mandibles.  To see the album click on photo at left.