Imaging Inflammatory Processes of the Oral Cavity and Suprahyoid Neck

Distinguishing sterile inflammation from graft infection

We describe the case of a 68-year-old man who underwent ascending aortic replacement and thoracic endovascular aortic repair. Four years later, the patient developed neck pain on the right side and chest computed tomography showed expansion of fluid in the mediastinum which had extended to the neck. Echocardiography revealed advanced severity of aortic regurgitation and decreased ejection fraction. Given the progression of aortic regurgitation, decreased cardiac function, and rapidly expanding fluid accumulation causing neck pain, reoperation was indicated. All microbiological test including polymerase chain reaction were negative indicating absence of any infection. The patient is being followed-up without antibiotics and CT has not shown peri-graft fluid 2 years postoperatively. Since infection cannot be excluded completely, it is important to assess the condition with selective medium, extended culture periods, genetic testing, and consultations with microbiology laboratories when normal culture tests for general bacteria, and fungi are negative which can help avoid drug-resistant bacteria count, elevated medical costs, and drug side effects due to the improper use of antibiotics through proper diagnosis.

CT differentiation of abscess and non-infected fluid in the postoperative neck

BACKGROUND

Differentiation of postoperative neck abscess from non-infected fluid is important because the treatment is different.

PURPOSE

To determine specific CT findings that might help to differentiate abscesses from non-infected fluid collections in the postoperative neck.

MATERIAL AND METHODS

We retrospectively reviewed CT scans of 50 patients (43 men and 7 women; mean age, 62.5 ± 8.9 years) who had postoperative fluid collections in the neck (26 abscesses and 24 non-infected fluid collections). Diagnosis of an abscess was determined by a positive bacteria culture from the fluid collection. Diagnoses were correlated with the following CT findings: anatomic spaces involved, the maximum transverse diameter, margin, attenuation, rim enhancement, gas bubbles, and manifestations of soft tissue adjacent to a fluid collection.

RESULTS

Rim enhancement pattern and soft tissue manifestations showed significant differences between abscess and non-infected fluid. The reliable CT findings for abscess were: (i) rim enhancement > 50% of the circumference, 54% sensitive, 71% specific, and 62% accurate; and (ii) severe soft tissue manifestations, 39% sensitive, 92% specific, and 64% accurate. There were no significant differences in the anatomic spaces involved, the maximum transverse diameter, margin, attenuation, and gas bubbles between abscess and non-infected fluid.

CONCLUSION

CT findings that may help differentiate postoperative neck abscess from non-infected fluid were rim enhancement > 50% of the circumference and severe soft tissue manifestations.

MR imaging of benign and malignant lesions in the buccal space

OBJECTIVES

To evaluate MRI characteristics of buccal space lesions and to discuss the sensitivity of MRI in predicting malignancy of those lesions.

METHODS

Thirty patients with malignant (n=7) or benign (n=23) lesions originating in the buccal space were reviewed retrospectively. MR images were assessed for the margins, internal architecture, signal intensity of lesions and their relation to the surrounding structures.

RESULTS

Two cases of soft tissue sarcoma were shown as ill-defined masses with infiltration into adjacent muscles and bone. On the other hand, all tumors of minor salivary gland origin, whether malignant (n=4) or benign (n=2), were well-defined and confined within the buccal fat pad without infiltration into surrounding structures. All haemangiomas (n=9) had very high T2-weighted signal intensity. Three out of them contained signal voids on all sequences thought to represent phleboliths, a finding strongly suggestive of the diagnosis. Inflammatory lesions were characterized by the presence of edema in the surrounding fat. When ill-defined margins, infiltration into muscles and bone destruction were used as the criteria for the malignancy, only two out of seven malignant tumors were correctly diagnosed (sensitivity 29%).

CONCLUSIONS

Although MR imaging was useful in demonstrating the extent of buccal space lesions, its diagnostic value in predicting malignancy was very limited. It was especially true for malignant tumors of minor salivary gland origin, which were typically seen as well-defined masses without infiltration into surrounding structures on MRI.

Acute neck infections: prospective comparison between CT and MRI in 47 patients

PURPOSE

The purpose of this work was to assess the advantages and disadvantages of MRI versus CT in the initial evaluation of acute infections involving the neck.

METHOD

We prospectively evaluated 47 patients with neck infections. All patients underwent CT and MRI with contrast of the area of interest using similar slice thickness. Final diagnosis was achieved by percutaneous aspiration, surgical exploration and drainage, or follow-up after successful antibiotic therapy in all patients. Two radiologists reviewed all imaging studies with special attention to lesion conspicuity, location, extension, bone involvement, source of infection (odontogenic versus nonodontogenic), and presence of gas and/or calcium in the lesions. A 3 point scale was used to grade these parameters, and statistical comparison was done using paired t test.

RESULTS

As used in our population, MRI was superior to CT in regard to lesion conspicuity, number of anatomic spaces involved, extension, and source. Additionally, although not statistically significantly, MRI detected a greater number of abscess collections. CT was superior to MRI in the detection of intralesional gas and calcium and showed fewer motion artifacts. These advantages of CT were, however, not significantly better than those of MRI.

CONCLUSION

As used in our study, MRI was considered superior to CT in the initial evaluation of neck infections. Our findings suggest that MRI may be used as the first and perhaps the only modality to initially evaluate patients with neck infections when clinically feasible.

Odontogenic versus nonodontogenic deep neck space infections: CT manifestations

PURPOSE

The purpose of this study was to evaluate deep neck space infection (DNSI) with particular attention to the differences in the spaces involved and in complications between odontogenic and nonodontogenic groups with CT.

METHOD

Forty-four patients (21 odontogenic and 23 nonodontogenic) were included in this study. Among odontogenic DNSI cases, 15 had dental infection in the second or third mandibular molar. We compared the CT features between odontogenic and nonodontogenic DNSI cases, with special emphasis on the differences in the spaces involved and in the rate and type of complications.

RESULTS

In all patients, CT clearly differentiated abscess from cellulitis. The most common spaces involved in 21 patients with odontogenic DNSI were the parapharyngeal (n = 18), the submandibular (n = 18), the anterior visceral (n = 13), the masticator (n = 9), and the sublingual (n = 7) spaces. In contrast, in 23 patients with nonodontogenic DNSI, the anterior visceral space (n = 14) was most frequently involved. The parapharyngeal, submandibular, and masticator spaces were statistically more frequently involved in odontogenic than in nonodontogenic DNSI (p < 0.05). Twenty-two patients had one or more complications shown by CT, of which airway compromise was more frequent and severe in odontogenic than in nonodontogenic DNSI.

CONCLUSION

We conclude that the parapharyngeal, submandibular, and masticator spaces are more significantly vulnerable in odontogenic DNSI than in nonodontogenic DNSI. The predilection for certain spaces of the neck in odontogenic DNSI seems to originate from the intimate relationship of the mandibular molars to the adjacent deep neck spaces.

Advances in maxillofacial imaging

The maxillofacial region, extending from the base of the skull to the hyoid bone, is one of the most anatomically complex regions of the body. This area contains elements and organs belonging to a number of different systems that can be affected by a variety of local and systemic pathologic processes. Diagnostic imaging has assumed a central role in the evaluation of this region. In the following monograph, we present the reader with an overview of contemporary maxillofacial imaging, focusing on three areas: recent technical advances that impact on the diagnosis of the maxillofacial region, the appearances of various maxillofacial lesions on different imaging modalities, and an overview of the role of diagnostic imaging in the evaluation of the orthognathic patient. In the first section, we focus on recent technical advances in diagnostic imaging as they relate to the maxillofacial region. Imaging modalities discussed include panoramic radiography and three-dimensional imaging. We also examine the uses of recently developed computed tomography software for the evaluation of the dental implant patient and discuss the roles of both noninteractive and interactive software in this process. The second section focuses on the radiographic appearance of a number of common lesions involving the maxillofacial region. In this section, we use the gamut approach to examine a number of developmental, inflammatory, neoplastic, metabolic, and traumatic lesions or disorders. In the last section, we briefly review the subject of orthognathic surgery and the role of diagnostic imaging in the preoperative and postoperative evaluation of the orthognathic patient. The radiographic appearance of some of the more commonly performed midfacial osteotomies are presented.