Incidence of antiresorptive agent-related osteonecrosis of the jaw: A multicenter retrospective epidemiological study in Hyogo Prefecture, Japan.

Background/purpose: The incidence of medication-related osteonecrosis of the jaw is increasing worldwide, mostly due to the use of antiresorptive agents (ARAs) such as bisphosphonate (BP) and denosumab (Dmab). However, the proportion of BP-related osteonecrosis of the jaw (BRONJ) and Dmab-related osteonecrosis of the jaw (DRONJ) among all ARA-related osteonecrosis of the jaw (ARONJ) cases is not clear; this hinders appropriate treatment, recurrence-prevention planning, and avoidance of unnecessary Dmab withdrawal. Moreover, the causative drug administered at each disease stage remains unknown. Therefore, we conducted a retrospective study of patients with ARONJ who visited oral and maxillofacial surgery departments at hospitals in Hyogo Prefecture, Japan, over 3 years to classify and compare patient characteristics with those having BRONJ and DRONJ. We sought to identify the proportion of DRONJ in ARONJ. Materials and methods: After excluding stage 0 patients, 1021 patients were included (471 high-dose; 560 low-dose). ARA treatment for bone metastases of malignant tumors and multiple myeloma was considered high dose, while that for cancer treatment-induced bone loss and osteoporosis was low dose. Results: Low doses of BP and Dmab accounted for >50% patients; the results differed from those in other countries. DRONJ accounted for 58% and 35% of high-dose and low-dose cases, respectively. Stage 3 ARONJ cases comprised 92 (19.5%) low-dose BRONJ, 39 (20.1%) high-dose BRONJ, 24 (30%) low-dose DRONJ, and 68 (24.5%) high-dose DRONJ. Eighty-nine patients who received switch therapy were divided into BRONJ or DRONJ, but there was no difference in the ratio of each stage compared to the non-switch therapy. Conclusion: To the best of our knowledge, this is the first study to clarify the proportion of BRONJ and DRONJ cases, causative drug, and its doses by disease stages. DRONJ accounted for approximately 30% of the ARONJ, approximately 60% of which was due to high doses.

Comparative Efficacy of Granisetron and Droperidol After Orthognathic Surgery for Prophylaxis of Postoperative Nausea and Vomiting: A Retrospective Study.

BACKGROUND: In the fall of 2021, granisetron was approved for postoperative nausea and vomiting (PONV) management in Japan. However, the comparative efficacy of droperidol and granisetron in the field of orthognathic surgery has not been determined. PURPOSE: We compare the efficacy of droperidol and granisetron for PONV prophylaxis following orthognathic surgery. STUDY DESIGN, SETTING, SAMPLE: We performed a retrospective cohort study of patients who underwent orthognathic surgery at a single institution from September 2020 to December 2022. Patients who had undergone Le Fort I osteotomy with sagittal split ramus osteotomy or isolated sagittal split ramus osteotomy were included. Patients were divided into three groups; the isolated droperidol (D), isolated granisetron (G), and droperidol with granisetron (DG) groups. General anesthesia was performed using total intravenous anesthesia for all patients; however, droperidol and granisetron were administered at the anesthesiologist's discretion. PREDICTOR VARIABLE: PONV prophylactic therapy included isolated droperidol, isolated granisetron, and droperidol with granisetron administration. OUTCOME VARIABLES: Postoperative nausea (PON) and postoperative vomiting (POV) were determined through medical examination within 48 hours following surgery. Secondary outcomes included complications due to droperidol and/or granisetron administration. COVARIATES: Age, sex, body mass index, Apfel's score, duration of surgery, duration of anesthesia, intraoperative blood loss, and type of surgery. ANALYSES: Statistical analysis was conducted using Fisher exact test, Mann-Whitney U test with Bonferroni correction for univariate comparison, and modified Poisson regression for comparison of PON and POV prophylactic efficacy for multivariate analyses. P values <.05 were considered statistically significant. RESULTS: Our study included 218 participants. There were no significant differences in covariates between groups D (n = 111), G (n = 52), and DG (n = 55). No significant difference in PON incidence was observed between groups. However, POV incidence was significantly lower in group DG than group D (relative risk, 0.21; 95% confidence interval, 0.05 to 0.86; P = .03). No significant difference in complication incidence was observed between groups. CONCLUSIONS AND RELEVANCE: Granisetron was as effective as droperidol for PONV management, while droperidol combined with granisetron was more effective than isolated droperidol for POV management. As compared to the use of each drug separately, their combination was considered safe, with no increase in complication rates.

Clinical risk factors for severity and prognosis of antiresorptive agent-related osteonecrosis of the jaw: a retrospective observational study.

INTRODUCTION: The incidence of antiresorptive agent-related osteonecrosis of the jaw (ARONJ) is rare, and its management has not yet been established. This study aimed to investigate the predictors for advanced stage and healing of ARONJ to establish an appropriate treatment strategy. MATERIALS AND METHODS: We retrospectively analyzed patients diagnosed with ARONJ at Kobe City Medical Center General Hospital between April 2014 and March 2020. Outcomes were defined as stage ≥ 2 ARONJ (primary) and healing of ARONJ (secondary). Multivariate logistic regression analysis was used to detect factors associated with the outcomes, and odds ratios (OR) and 95% confidence intervals (CI) were calculated. RESULTS: This study included 143 patients (stage ≥ 2 ARONJ, 51%; healing of ARONJ, 60%). Multivariate logistic regression analysis revealed that advanced age (per year) (OR 1.037; 95% CI 1.003-1.072; p = 0.028) and serum albumin (per g/dL) (OR 0.430; 95% CI 0.213-0.869; p = 0.018) were significantly associated with stage ≥ 2 ARONJ. Furthermore, multivariate logistic regression analysis revealed that cancer (yes) (OR 0.099; 95% CI 0.029-0.339; p < 0.001), conservative surgical treatment (yes) (OR 15.42; 95% CI 5.657-42.0; p < 0.001), C-reactive protein (per mg/dL) (OR 0.599; 95% CI 0.415-0.864; p < 0.001), and vitamin D analog (yes) (OR 0.167; 95% CI 0.034-0.827; p = 0.028) were factors associated with healing. CONCLUSION: Our findings suggest that age and hypoalbuminemia are associated with the severity of ARONJ, and cancer, high inflammation, and vitamin D analog may impair healing. In contrast, conservative surgical treatment can overcome the poor treatment outcomes associated with ARONJ.

Clinical features and antimicrobial susceptibility of oral bacteria isolated from the blood cultures of patients with infective endocarditis.

Background/purpose: The epidemiology of infective endocarditis (IE) is under constant change due to the aging society and increases in antimicrobial-resistant pathogens. However, IE remains severe. This study aimed to review the current clinical characteristics of IE and the antimicrobial susceptibility of oral bacteria (OB) isolated from blood cultures to implement appropriate antimicrobial prophylaxis. Materials and methods: We retrospectively investigated the clinical features of 180 patients with IE in whom OB and pathogens except OB (eOB) were identified as causative microorganisms via blood cultures. The susceptibility of the OB group to eight antibiotics was examined by broth microdilution. Results: Among causative microorganisms, the isolation rate of staphylococci was slightly higher than that of OB; however, the difference was not significant (36.7% vs. 33.8%, p = 0.3203). The number of patients with underlying cardiac disease was significantly higher in the OB group than in the eOB group (53.7% vs. 34.1%, p = 0.0113). Only one ampicillin-resistant OB was detected (2.0%). OBs were significantly less susceptible to clarithromycin and azithromycin than to ampicillin (98.0% vs. 66.7% and 98.0% vs. 60.0%, p = 0.0003 and p = 0.0003, respectively). Moreover, OBs were significantly less susceptible to clarithromycin and azithromycin than to clindamycin (66.7% vs. 88.2% and 60.0% vs. 88.2%, p = 0.0301 and p = 0.0217, respectively). Conclusion: OBs were susceptible to ampicillin. However, the susceptibility of OBs to clarithromycin and azithromycin was significantly lower than that to ampicillin and clindamycin. These results are important and should help decisions regarding guide antimicrobial prophylaxis.

Ulcers on the bilateral palate mucosa following mRNA-based vaccination for coronavirus disease 2019 (COVID-19): A case report.

Severe acute respiratory syndrome coronavirus 2 has spread globally. Vaccination for coronavirus disease 2019 (COVID-19) is anticipated to reduce morbidity and mortality. However, the safety of vaccines against COVID-19 is a cause for concern and uncertainty, which leads to vaccine hesitancy. There have been some self-reported questionnaire studies regarding adverse effects after COVID-19 vaccination; however, adverse effects on the oral region are rare. In this report, we present one case of ulcers arising on the bilateral palate mucosa following COVID-19 vaccination, which was suspected to be an adverse effect of vaccination.

Postoperative dysphagia caused by a delay in mandibular fracture treatment in a patient with severe intellectual disability: a case report.

BACKGROUND: The postoperative complications of mandibular fracture include malocclusion, infection, nonunion, osteomyelitis, and sensorial mental nerve dysfunction. However, there are no reports regarding postoperative dysphagia as a complication of mandibular fracture. Herein, we report a rare case of postoperative dysphagia caused by delayed mandibular fracture treatment in a patient with severe intellectual disability. CASE PRESENTATION: A 46-year-old Japanese male patient with severe intellectual disability fell down and struck his chin. The patient was referred to our department 10 days after the accident. Upon examination, he could not close his mouth because of severe left mandibular body fracture. Open reduction and internal fixation was performed under general anesthesia 16 days after sustaining the injury, and normal occlusion was eventually achieved. However, the patient could not swallow well a day after surgery. He was then diagnosed with postoperative dysphagia caused by disuse atrophy of muscles for swallowing based on videoendoscopic examination findings. Adequate dysphagia rehabilitation could not be facilitated because of the patient's mental status. Postoperative dysphagia did not improve 21 days after surgery. Therefore, percutaneous endoscopic gastrostomy was required. CONCLUSIONS: The treatment course of the patient had two important implications. First, postoperative dysphagia caused by disuse atrophy may occur if treatment is delayed in severe mandibular body fracture. Second, in particular, if a patient with severe intellectual disability develops postoperative dysphagia caused by disuse atrophy, adequate dysphagia rehabilitation cannot be facilitated, and percutaneous endoscopic gastrostomy may be required. Therefore, early open reduction and internal fixation is required for mandibular fracture in a patient with severe intellectual disability.

Risk evaluation of denosumab and zoledronic acid for medication-related osteonecrosis of the jaw in patients with bone metastases: a propensity score-matched analysis.

PURPOSE: This study evaluated the risk of medication-related osteonecrosis of the jaw (MRONJ) in patients with cancer who received denosumab or zoledronic acid (ZA) for treating bone metastasis. METHODS: The medical records of patients were retrospectively reviewed. Patients who did not undergo a dental examination at baseline were excluded. The primary endpoint was a comparison of the risk of developing MRONJ between the denosumab and ZA groups. Propensity score matching was used to control for baseline differences between patient characteristics and compare outcomes for both groups. RESULTS: Among the 799 patients enrolled, 58 (7.3%) developed MRONJ. The incidence of MRONJ was significantly higher in the denosumab group than in the ZA group (9.6% [39/406] vs. 4.8% [19/393], p = 0.009). Multivariate Cox proportional hazards regression analysis revealed that denosumab treatment (hazard ratio [HR], 2.89; 95% confidence interval [CI], 1.65-5.25; p < 0.001) and tooth extraction after starting ZA or denosumab (HR, 4.26; 95% CI, 2.38-7.44; p < 0.001) were significant risk factors for MRONJ. Propensity score-matched analysis confirmed that the risk of developing MRONJ was significantly higher in the denosumab group than in the ZA group (HR, 2.34; 95% CI, 1.17-5.01; p = 0.016). CONCLUSION: The results of this study suggest that denosumab poses a significant risk for developing MRONJ in patients treated for bone metastasis, and thus these patients require close monitoring.

Switching from zoledronic acid to denosumab increases the risk for developing medication-related osteonecrosis of the jaw in patients with bone metastases.

PURPOSE: Switch from zoledronic acid (ZA) to denosumab may increase the risk of medication-related osteonecrosis of the jaw (MRONJ) owing to the additive effect of denosumab on the jawbone and residual ZA activities. We evaluated the risk of developing MRONJ in patients who received ZA, denosumab, or ZA-to-denosumab for the treatment of bone metastases. METHODS: The medical charts of patients with cancer who received denosumab or ZA for bone metastases were retrospectively reviewed. Patients who did not undergo a dental examination at baseline were excluded. Primary endpoint was the evaluation of the risk of developing MRONJ in the ZA-to-denosumab group. Secondary endpoints were probability of MRONJ and the relationship between risk factors and the time to the development of MRONJ. RESULTS: Among the 795 patients included in this study, 65 (8.2%) developed MRONJ. The incidence of MRONJ was significantly higher in the ZA-to-denosumab group than in the ZA group [7/43 (16.3%) vs. 19/350 (5.4%), p = 0.007]. Multivariate Cox proportional hazards regression analysis revealed that denosumab treatment [hazard ratio (HR), 2.41; 95% confidence interval (CI), 1.37-4.39; p = 0.002], ZA-to-denosumab treatment (HR, 4.36; 95% CI, 1.63-10.54, p = 0.005), tooth extraction after starting ZA or denosumab (HR, 4.86; 95% CI, 2.75-8.36; p < 0.001), and concomitant use of antiangiogenic agents (HR, 1.78; 95% CI, 1.06-2.96; p = 0.030) were significant risk factors for MRONJ. CONCLUSION: Our results suggest that switching from ZA to denosumab significantly increases the risk for developing MRONJ in patients with bone metastases.

Acquired hemophilia A that required surgical hemostasis of hematomas occupying oral cavity: a case report.

BACKGROUND: Acquired hemophilia A is a rare coagulopathy caused by inhibitors of blood coagulation factor VIII. Patients with acquired hemophilia A have a higher mortality risk (5-10%) than those with congenital hemophilia. Moreover, there is no established evidence of management recommended for patients with acquired hemophilia A. Previous studies have reported the presence of hematomas in the oral cavities of patients with acquired hemophilia A, which were treated conservatively. Here, we describe the case of a patient with acquired hemophilia A, where emergency surgical hemostasis was required for large intraoral hematomas. CASE PRESENTATION: A 65-year-old Japanese man was referred to our hospital with a chief complaint of bleeding from large intraoral hematomas. On examination, he could not close his mouth because of the hematomas, which were bleeding spontaneously. Computed tomography angiography revealed no evidence of arteriovenous malformation, and blood test results showed that the activated partial thromboplastin time was elevated beyond the normal limit. To avoid a life-threatening hemorrhage from hematomas, emergency surgical hemostasis was performed with nasotracheal intubation using fiberoptic bronchoscopy. Hemostasis was successfully performed, as the hematomas were carefully removed. Moreover, the clinical course was successfully completed using intravenously administered activated prothrombin complex concentrate for hemostasis after operation. CONCLUSIONS: Acquired hemophilia A can cause a life-threatening hemorrhage without predictive factors. Intraoral hematoma may cause airway obstruction. There is no consensus regarding the management of hemorrhage in patients with acquired hemophilia A. As shown here, exophytic hematomas in the oral cavity can be safely removed and nasotracheal intubation with fiberoptic bronchoscopy may be useful in patients with coagulopathy disease.

Associated characteristics and treatment outcomes of medication-related osteonecrosis of the jaw in patients receiving denosumab or zoledronic acid for bone metastases.

PURPOSE: This study aimed to evaluate the association between clinical characteristics and development of medication-related osteonecrosis of the jaw (MRONJ) in patients who underwent dental examinations before the initiation of treatment with denosumab or zoledronic acid, which are bone-modifying agents (BMAs), for bone metastases. Additionally, the clinical outcomes of patients who developed MRONJ were evaluated along with the time to resolution of MRONJ. METHODS: The medical charts of patients with cancer who received denosumab or zoledronic acid for bone metastases between January 2012 and September 2016 were retrospectively reviewed. Patients were excluded if they did not undergo a dental examination at baseline. RESULTS: Among the 374 included patients, 34 (9.1%) developed MRONJ. The incidence of MRONJ was significantly higher in the denosumab group than in the zoledronic acid (27/215 [12.6%] vs 7/159 [4.4%], P = 0.006) group. Multivariate Cox proportional hazards regression analysis revealed that denosumab treatment, older age, and tooth extraction before and after starting BMA treatments were significantly associated with developing MRONJ. The time to resolution of MRONJ was significantly shorter for patients who received denosumab (median 26.8 months) than for those who received zoledronic acid (median not reached; P = 0.024). CONCLUSION: The results of this study suggest that treatment with denosumab, age > 65 years, and tooth extraction before and after starting BMA treatments are significantly associated with developing MRONJ in patients undergoing treatment for bone metastases. However, MRONJ caused by denosumab resolves faster than that caused by zoledronic acid.

A Case of Infective Endocarditis Due to Oral Streptococci After Perioperative Oral Function Management.

Infective endocarditis is an extremely serious disease that can present with a variety of clinical manifestations, including infection of valves and endocardium, in patients with cardiac disease, and is associated with risk factors such as invasive dental procedures, caries, and periodontal disease. On the other hand, it has been shown that perioperative oral function management before various surgeries, such as those for malignant tumors, cardiovascular disease, and transplantation, may prevent or reduce postoperative complications. Close coordination between the dentist and cardiac surgeon is especially necessary before heart valve surgery because of the risk of severe complications. The number of perioperative oral management procedures being performed in community dental clinics is increasing. In the absence of clear guidelines, the physician-in-charge usually determines how to best perform oral management while considering the patient's needs. We report a case of infective endocarditis occurring after perioperative oral management in a young patient with good oral hygiene. This case shows that standardization of the techniques and widespread dissemination of the guidelines are required. Patients should be counseled regarding the importance of maintaining oral hygiene from a young age. This case report should act as a cautionary tale not only for hospital clinicians but also for community medical and dental practitioners, as the number of such patients is expected to increase in the future.

A Splint-to-CT Data Registration Strategy for Maxillary Navigation Surgery.

Computer-assisted navigation plays an important role in modern craniomaxillofacial surgery. Although headpins and skull posts are widely used for the fixation of the reference frame, they require the use of invasive procedures. Headbands are easily displaced intraoperatively, thus reducing the accuracy of the surgical outcome. This study reported the utility of a novel splint integrated with a reference frame and registration markers for maxillary navigation surgery. A maxillary splint with a 10 cm resin handle was fabricated before surgery, to fix the reference frame to the splint. The splint was set after the incorporation of fiducial gutta-percha markers into both the splint and resin handle for marker-based pair-point registration. A computed tomography (CT) scan was acquired for preoperative CT-based planning. A marker-based pair-point registration procedure can be completed easily and noninvasively using this custom-made integrated splint, and maxillary navigation surgery can be performed with high accuracy. This method also provides maximum convenience for the surgeon, as the splint does not require reregistration, and can be removed temporarily when required. The splint-to-CT data registration strategy has potential applicability not only for maxillary surgery but also for otolaryngologic surgery, neurosurgery, and surgical repair after craniofacial trauma.

Osteomyelitis of the Mandible Caused by Late Fracture following Third Molar Extraction.

The common postoperative complications of the extraction of third molars are frequently reported; however, reports about osteomyelitis of the mandible caused by late fracture following third molar extraction are rare. Here, we report a case of osteomyelitis of the mandible caused by late fracture following third molar extraction. A 38-year-old Japanese man was referred to the surgery department with chief complaints of dull pain and swelling in the right masseteric region and paresthesia of his lower lip and mental region in March 2018. A family dentist removed his lower third molar in the right side in January 2018. When the patient was chewing an innards stew 23 days after the procedure, he heard a cracking sound from the right mandible. Thus, we diagnosed the patient as having osteomyelitis of the mandible caused by late fracture following third molar extraction and performed sequestrectomy and curettage under general anesthesia in April 2018. In conclusion, it is necessary to recognize the possibility that late fracture following third molar extraction can cause osteomyelitis. Furthermore, once osteomyelitis of the mandible caused by late fracture occurred, early and appropriate treatment is necessary because the osteomyelitis may progress rapidly and in some cases may result in pathological fracture.

Development of Antiresorptive Agent-Related Osteonecrosis of the Jaw After Dental Implant Removal: A Case Report.

Dental implant treatment is a highly predictable therapy, but when potentially lethal symptoms or complications occur, dentists must remove the implant fixture. Recently, reports on antiresorptive agent-related osteonecrosis of the jaw have increased in the field of dental implants, although the relationship between dental implant treatment and antiresorptive agents remains unclear. Here, we report a case of antiresorptive agent-related osteonecrosis of the jaw that developed after dental implant removal. A 67-year-old Japanese woman with a medical history of osteoporosis and 7 years of oral bisphosphonate treatment was referred to our hospital with a chief complaint of painful right mandibular bone exposure. A family dentist removed the dental implants from the right mandible using a trephine drill without flap elevation in August 2016. However, the healing was impaired; she was referred to our hospital 3 months after the procedure. We performed a sequestrectomy of the mandible under general anesthesia. In conclusion, this patient's course has two important implications: First, the removal of dental implants from patients who are prescribed oral bisphosphonates for long durations can cause antiresorptive agent-related osteonecrosis of the jaw. Second, meticulous procedures are required to prevent and treat the development of antiresorptive agent-related osteonecrosis of the jaw after dental implant removal.

Actinomycotic Osteomyelitis of the Mandible Diagnosed Using Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry: A Case Report.

Actinomycosis is a rare, chronic, slowly progressive granulomatous disease caused by filamentous gram-positive anaerobic bacteria from the Actinomycetaceae family (genus Actinomyces). It has become a rare condition because of the widespread use of antibiotics. When clinical symptoms are not typical, diagnosis of this condition becomes difficult. This report describes a case involving an 82-year-old woman who was diagnosed with actinomycotic osteomyelitis of the mandible using matrix assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). The patient was referred to the authors' department with chief complaints of swelling, multiple fistulae in the left preauricular region, and trismus. The authors performed fine-needle aspiration microbiology (FNAM) and identified Actinomyces oris using MALDI-TOF MS. A diagnosis of actinomycotic osteomyelitis of the mandible was made and the patient was treated with minocycline and extraction of the culprit tooth. The findings from this case have 2 important implications. First, for patients with clinically suspected actinomycosis, bacteriologic examinations should include not only surface swab tests but also FNAM; moreover, communication with the laboratory medical technologist is important to improve detection of the causative organisms. Second, MALDI-TOF MS could be an effective tool for improving the diagnosis and treatment outcomes of actinomycosis.

Surgical Ciliated Cyst Following Maxillary Sinus Floor Augmentation: A Case Report.

Maxillary sinus floor augmentation is considered to play a critical role in dental implant treatment. Although many complications, such as maxillary sinusitis and infection, are well known, few reports are available on the risk of surgical ciliated cyst following the procedure. Here, we report a case of surgical ciliated cyst following maxillary sinus floor augmentation. A 55-year-old Japanese woman was referred to our hospital because of alveolar bone atrophy in the bilateral maxilla. We performed bilateral maxillary sinus floor augmentation by the lateral window technique without covering the window. The Schneiderian membrane did not perforate during the operation. She returned to our hospital after 9 years due to swelling of the left buccal region. Computerized tomography revealed a well-defined radiolucent area with radiodense border intraosseously localized in the left maxilla. We performed enucleation of the cyst with the patient under general anesthesia. Histological examination of the specimen showed a surgical ciliated cyst. In conclusion, the course of this patient has 2 important implications. First, the sinus membrane entrapped in the grafted bone without visible perforation and or tearing can develop into a surgical ciliated cyst. Second, there is a possibility that covering the lateral window tightly might prevent the development of a surgical ciliated cyst.

Case series: conditions inhibiting eruption of permanent first molars.

PURPOSE: The purpose of this study was to evaluate the radiological and histopathological findings of 11 patients with unerupted first molars to verify the factors obstructing spontaneous eruption. METHODS: The patients' clinical, radiological, and histopathological data were evaluated retrospectively to determine histopathological diagnosis, radiographic findings, methods of surgical management, and postoperative course. RESULTS: This study involved 4 male and 7 female patients (mean age=9.5 years old). Nine cases involved the mandible. The patients' histopathological diagnoses included 3 odontogenic tumors, 2 odontogenic cysts, and 6 hyperplastic dental follicles. Radiographically, 10 cases showed characterless enlargement of the follicular space, while only 1 displayed radiopaque bodies. One patient with a tumor underwent enucleation, and 1 with a cyst underwent cystectomy and tooth extraction. The others underwent wide excision or partial excision of the surrounding tissue at the top of the impacted tooth. Tumor relapse was observed in 3 cases. CONCLUSION: Surgeons should perform aggressive treatment for patients with unerupted teeth because spontaneous eruption is rare in cases involving non-neoplastic lesions such as hyperplastic dental follicles.

Magnetic resonance imaging (MRI) and dynamic MRI evaluation of extranodal non-Hodgkin lymphoma in oral and maxillofacial regions.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic value of magnetic resonance imaging (MRI), especially dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), in extranodal non-Hodgkin lymphoma (NHL) of oral and maxillofacial regions. STUDY DESIGN: Thirteen cases with extranodal NHL were examined using MRI. T1-weighted images (T1WI) and T2-weighted images (T2WI) or short TI inversion recovery (STIR) images were obtained in all cases. Contrast-enhanced images and DCE-MRI were acquired in 10 and 7 cases, respectively. On DCE-MRIs, we analyzed the parameters as follows: contrast index at maximal contrast enhancement (CImax), maximum contrast index (CI) gain/CImax ratio, and washout ratios (WR(300), WR(600), and WR(900)) at 300, 600, and 900 seconds after contrast medium injection. RESULTS: The signal intensity of all lesions was hypointense to isointense on T1WIs and showed variable contrast enhancement patterns. On T2WIs and STIR images, the signal intensity was isointense to hyperintense in almost all cases. Analysis of DCE-MRI parameters in extranodal NHLs resulted in the identification of 4 types of CI curves according to CImax and WR: (1) CImax greater than 2.0 and WR(900) greater than 40%, (2) CImax greater than 2.0 and WR(900) less than 40%, (3) CImax less than 1.5 and WR(900) greater than 40%, and (4) CImax less than 1.5 and WR(900) greater than 40%. CONCLUSIONS: The signal intensities on MRI were not specific to extranodal NHL and resembled those of other tumor types. When CImax was less than 1.5 or WR900 was less than 40%, these parameters contributed to diagnosis in extranodal NHLs.