Preliminary assessment of benign maxillofacial and neck lesions with in vivo single-voxel 1H magnetic resonance spectroscopy

Actual applications of magnetic resonance imaging in dentomaxillofacial region

Magnetic resonance imaging (MRI) is a versatile imaging modality utilized in various medical fields. Specifically used for evaluation of soft tissues, with non-ionizing radiation and multiplanar sections that has provided great guidance to diagnosis. Nowadays, use of MRI in dental practice is becoming more pervasive, especially for the evaluation of head-and-neck cancer, detection of salivary gland lesions, lymphadenopathy, and temporomandibular joint disorders. Understanding the basic principles, its recent advances, and multiple applications in dentomaxillofacial region helps significantly in the diagnostic decision making. In this article, the principle of MRI and its recent advances are reviewed, with further discussion on the appearance of various maxillofacial pathosis.

Multimodality fMRI with perfusion, diffusion-weighted MRI and 1 H-MRS in the diagnosis of lympho-associated benign and malignant lesions of the parotid gland

BACKGROUND

Differential diagnosis of the mucosa-associated lymphoid tissue lymphoma (MALToma) and tumor-like benign lymphoepithelial lesion (BLEL) in the parotid gland is difficult.

PURPOSE

To distinguish MALToma and BLEL with multimodality MRI including hydrogenproton magnetic resonance spectroscopy (¹ H-MRS), diffusion-weighted imaging (DWI-MR), and dynamic contrast-enhanced (DCE-MR), and evaluate each sequence.

STUDY TYPE

Retrospective.

POPULATION

Twenty-five patients with parotid tumor-like BLEL and 20 with parotid MALToma.

FIELD STRENGTH/SEQUENCE

1.5-T/T₁ WI, T₂ WI, single-voxel ¹ H-MRS, DWI-MR, and DCE-MR.

ASSESSMENT

All MR images were interpreted and agreed upon by two radiologists who were blinded to clinical information and histopathologic results. The imaging diagnoses were then compared to the histopathologic results.

STATISTICAL TESTS

Youden index was used to determine the optimized threshold value. The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic efficiency of different functional (f)MRI methods.

RESULTS

Fisher's exact test indicated a significant difference between the ¹ H-MRS images of the two lesions (P < 0.001). The sensitivity, specificity, and accuracy of positive choline (Cho) peak in ¹ H-MRS of parotid MALToma were 80%, 76%, and 77.7%, respectively. The mean apparent diffusion coefficient (ADC) was 0.992 × 10^-3 mm² /s in patients with parotid tumor-like BLEL and 0.634 × 10^-3 mm² /s in patients with parotid MALToma, and the difference was statistically significant (t-test, P < 0.001). Choosing the Youden index as 0.669 × 10^-3 mm² /s, the sensitivity, specificity, and accuracy of the assay were 78.9%, 95.8%, and 88.4%, respectively. Assuming that time-intensity curve (TIC) type I indicated parotid MALToma (positive), and type II and type III indicated parotid tumor-like BLEL (negative), the sensitivity, specificity, and accuracy of time-to-peak (TTP) and initial slope of increase (ISI) in diagnosing MALToma were 94.1%, 95.2%, and 94.7%, respectively. Combining methods of TTP, ADC, and Cho peak reached the highest AUC (1.000).

DATA CONCLUSION

Combined use ¹ H-MRS, DWI-MR, and DCE-MR increased the accuracy of the differential diagnosis between these lesions to 100%. Cho peak in ¹ H-MRS, ADC less than 0.669 × 10^-3 mm² /s, TIC type I together indicated parotid MALToma.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:423-432.

State of the art MRI in head and neck cancer

Head and neck cancer affects more than 11,000 new patients per year in the UK¹ and imaging has an important role in the diagnosis, treatment planning, and assessment, and post-treatment surveillance of these patients. The anatomical detail produced by magnetic resonance imaging (MRI) is ideally suited to staging and follow-up of primary tumours and cervical nodal metastases in the head and neck; however, anatomical images have limitations in cancer imaging and so increasingly functional-based MRI techniques, which provide molecular, metabolic, and physiological information, are being incorporated into MRI protocols. This article reviews the state of the art of these functional MRI techniques with emphasis on those that are most relevant to the current management of patients with head and neck cancer.

Cutaneous Rosai-Dorfman Disease of the Face: A Comprehensive Literature Review and Case Report

PURPOSE

Cutaneous Rosai-Dorfman disease (C-RDD) is a rare, benign, non-Langerhans cell histiocytosis that can affect any skin area. The purpose of this study was to characterize C-RDD of the face through a literature review of published case reports of this lesion and present a new case of C-RDD.

MATERIALS AND METHODS

An English-language search of 3 databases (PubMed, Scopus, and EBSCO Search) was conducted for cases of C-RDD of any skin area that had been published since 1969. Repeated citations of the same article in more than 1 database were deleted. Cases of C-RDD with solely facial involvement or involving the face and other skin parts were included and analyzed. Details of C-RDD cases (demographic features, regional distribution, clinical presentation, treatment, and follow-up course) were methodically reviewed and collected in Excel spreadsheets. Simple statistical analyses were conducted using Excel.

RESULTS

The literature search yielded 578 published cases of C-RDD affecting any skin area; of these, 65 cases (11.2%) had facial skin involvement. The male-to-female ratio was 1:1.5, and the average age at presentation was 43.5 years (standard deviation, 12.4 yr). The racial distribution of facial C-RDD was, in descending order, 74.5% in Asians, 20% in Caucasians, and 5.5% in blacks. The most commonly affected facial skin regions were the cheeks and periorbital area, and most lesions were multiple in number and bilaterally distributed. The vast majority of facial C-RDD lesions presented as asymptomatic, nonulcerative, red, nodular plaques with durations ranging from 1 month to a few years. Many methods have been attempted for the treatment of facial C-RDD. However, the combined cure rate for all published treatment methods was only 28.6%. Surgical excision was the most effective treatment method, and corticosteroids were the least effective.

CONCLUSION

This article has tried to characterize facial C-RDD lesions for easier management by maxillofacial surgeons.

MR spectroscopy of head and neck cancer

The aim of this review is to discuss the technique and potential applications of magnetic resonance spectroscopy (MRS) in head and neck cancer. We illustrate the technical issues related to data acquisition, post processing and interpretation of MRS of head and neck lesions. MRS has been used for differentiation of squamous cell carcinoma from normal tissue. The main potential clinical application of proton MRS ((1)H-MRS) is monitoring patients with head and neck cancer undergoing therapy. Pretreatment prediction of response to therapy can be done with phosphorus MRS ((31)P-MRS). Although performance of MRS of head and neck is challenging, technological advances in both software and hardware has the potential to impact on the clinical management of patients with head and neck cancer.

Desmoplastic fibroma of the mandible

Desmoplastic fibroma (DF) of the bone, also know as desmoid tumour, is a rare non-metastasizing but locally aggressive tumour. In this case report, we present imaging findings of a histopathologically proven desmoplastic fibroma involving the left mandibular region in a 15-year-old Chinese patient. We have also discussed the usefulness of different imaging modalities (plain film radiography, CT and MRI) in DF diagnosis and treatment.