In recent years, proactive surgical treatment has been reported to be effective for medication-related osteonecrosis of the jaw (MRONJ). However, an uncertain resection entails the risk of recurrence, whereas an extensive surgical procedure may lead to a marked reduction in quality of life as a result of reduced masticatory function and poor cosmesis. Therefore, radiological assessment can be helpful to accurately localize MRONJ before surgery. The integrated single-photon emission computed tomography and computed tomography system (SPECT/CT) allows oral and maxillofacial surgeons to identify an area of MRONJ, especially when three-dimensional (3D) SPECT and CT fusion images are offered. A patient for whom 3D SPECT and CT image fusion (as developed in the radiology department of the study institution) contributed to determining the extent of the lesion, thereby leading to a favourable patient prognosis, is reported herein. There was exact correlation between the histological and radiological results.
The 2014 American Association of Oral and Maxillofacial Surgeons (AAOMS) Position Paper on medication-related osteonecrosis of the jaw (MRONJ) states that conservative treatment is the primary therapy for stage 1 and 2 MRONJ, and a combination of surgery and medication is recommended for stage 3. Surgical treatment is a practical choice to achieve complete cure. However, an uncertain resection may result in further enlargement of the lesion, and overtreatment, such as an extensive jaw resection, may negatively impact quality of life (QOL). In this regard, a more accurate identification of the affected area is crucial for a successful surgical procedure.
A variety of radiological techniques have been applied to the evaluation of MRONJ. Among these is bone scintigraphy with bone-seeking radiopharmaceuticals including technetium-99m hydroxymethylene diphosphonate (99mTc-HMDP), which is based on the degree of tracer accumulation. Integrated single photon emission computed tomography and computed tomography (SPECT/CT) technology has recently been introduced to make it easier to identify an area of abnormal uptake by generating metabolic and morphological fusion images.
A three-dimensional (3D) SPECT/CT image fusion technique has been developed at Keio University School of Medicine and evaluated in the lung and sentinel lymph node. Since oral and maxillofacial surgeons often refer to replicas of the mandible when performing mandibular surgeries, this technique could serve as a guide for mandible MRONJ resection.
The case of a patient with MRONJ, in whom preoperative 3D SPECT/CT images showed a good correlation between radiological and histological results, is reported herein. Surgical removal of the affected region and reconstruction were achieved successfully, with favourable cosmetic and functional results. It is concluded that this new technique could be useful for detecting MRONJ, determining the region for surgical removal, and correlating the uptake area with the surgical specimen.
Patient and methods
A 51-year-old woman presented to the study hospital with the chief complaint of persistent drainage of pus from the lower jaw. She had been treated with zoledronic acid, 4 mg once a month for a total of 22 months, for spinal metastases of breast cancer. Her history was negative for other diseases or radiotherapeutic treatment. At the initial examination, loosening of all of the lower teeth was observed, with sequestra exposed in the oral cavity and purulent drainage from the submandibular area. A submandibular fistula was seen in the lower third of her face.
The patient was diagnosed with stage 3 MRONJ according to the diagnostic criteria in the 2014 AAOMS Position Paper. The preoperative radiological assessment consisted of panoramic X-ray, magnetic resonance imaging (MRI), and SPECT/CT. SPECT was performed 3 h after the administration of 99mTc-HMDP. For attenuation correction, which is generally employed as a part of a SPECT/CT scan to improve SPECT image quality in terms of quantitation of tracer uptake, a low-dose CT scan was performed followed by the SPECT acquisition. However, the image quality of low-dose CT is high enough to obtain 3D volume rendering images with our state-of-the-art SPECT/CT scanner (Discovery NM/CT 670pro, GE Healthcare) even though radiation exposure is minimized. The SPECT/CT data were processed using a Xeleris Workstation (GE Healthcare), and 3D SPECT/CT fusion images were generated using another image workstation (AW Server 2; GE Healthcare) ( Fig. 1 ).
In brief, the method of generating 3D fusion images developed by the present study group involves projecting SPECT data in colour onto the surface of the 3D volume rendered CT data after extracting the target tissue (i.e. mandibular bone). Therefore, this fusion image technique allows an abnormal uptake area to be exhibited on the CT data, providing a visual effect similar to that of contrast enhancement of the mandible in CT.
Based on the preoperative assessment, including the 3D fusion imaging, the extent of the resection was determined with a 1-cm margin from the abnormal accumulation of 99mTc-HMDP. A segmental resection of the mandible and a plate reconstruction procedure were then performed. A substantial amount of periosteum could be saved because there was no sign of periostitis.
Three months after the operation, complete improvement of the soft tissue inflammation around the surgical region without significant progression of mucosal atrophy was confirmed. In addition, the blood supply from periosteum and bone marrow at the resection stump was maintained. Therefore, it was decided to use a non-vascularized iliac bone graft for hard tissue reconstruction after providing the patient with a detailed explanation of the risks and benefits of this treatment. No intraoral incisions were performed during the reconstruction. Following this, the implantation of four Brånemark System Mk3 3.75 mm × 11.5 mm implants ( Fig. 2 ), a vestibuloplasty, free gingival grafting, and the installation of dentures were performed.
Histopathological assessment of the resected mandible revealed that chronic inflammatory cell infiltration and bacterial masses had spread to the site nearly 1 cm from the resection stumps ( Figs. 3 and 4 ); this was consistent with the area of abnormal accumulation on the SPECT/CT images ( Fig. 1 ). The resection stumps on both sides remained intact. No tumour cells were found in the resected tissues.
With regard to QOL, the patient’s Geriatric Oral Health Assessment Index (GOHAI) scores were 27, 29, and 47 points before the operation, just after the mandibular resection, and at the time of the final denture placement, respectively ( Table 1 ). Thus, satisfactory results in terms of both masticatory function and cosmesis were achieved.
|GOHAI items||Preoperative||Post initial operation||1-year postoperative|
|1. Limit the kinds of food eaten||1||1||3|
|2. Trouble biting or chewing||1||1||3|
|3. Problems swallowing comfortably||5||4||5|
|4. Problems speaking clearly||4||2||4|
|5. Discomfort when eating any kind of food||1||1||3|
|6. Limit contact with people||3||3||4|
|7. Pleased with appearance of teeth||1||2||4|
|8. Use medication to relieve pain||3||4||5|
|9. Worried about teeth, gums, or dentures||1||2||3|
|10. Self-conscious about teeth, gums, or dentures||2||3||4|
|11. Uncomfortable eating in front of others||2||1||4|
|12. Sensitive to hot, cold, or sweet foods||3||5||5|