Utility of apparent diffusion coefficient in characterization of different sinonasal pathologies

A practical overview of CT and MRI features of developmental, inflammatory, and neoplastic lesions of the sphenoid body and clivus

The sphenoid bone is an unpaired bone that contributes to the formation of the skull base. Despite the enormous progress in transnasal endoscopic visualisation, imaging techniques remain the cornerstones to characterise any pathological condition arising in this area. In the present review, we offer a bird’s-eye view of the developmental, inflammatory, and neoplastic alterations affecting the sphenoid body and clivus, with the aim to propose a practical diagnostic aid for radiologists based on clinico-epidemiological, computed tomography, and magnetic resonance imaging features.

MR imaging of Nasal and Paranasal Sinus Malignant Neoplasms

MRI is useful for evaluating sinonasal malignancies. In particular, MRI can provide important information pertinent to treatment planning, such as delineating the presence of intracranial and orbital extension. This article reviews the MRI protocols, staging, imaging features, and differential diagnosis related to malignant nasal and paranasal sinus neoplasms.

The value of the apparent diffusion coefficient calculated from diffusion-weighted magnetic resonance imaging scans in the differentiation of maxillary sinus inflammatory diseases

OBJECTIVES

This study examined the value of the apparent diffusion coefficient (ADC) calculated by using diffusion-weighted imaging (DWI) in the differentiation of inflammatory lesions of the maxillary sinus.

STUDY DESIGN

Sixty-five maxillary sinus magnetic resonance imaging (MRI) scans with findings suggestive of inflammatory lesions were qualitatively categorized into 4 distinct groups by using T2-weighted images: group 1: presence of mucosal thickening; group 2: presence of sinonasal polyps or mucous retention cysts; group 3: presence of fluid identified by air-fluid levels with a homogeneous signal intensity; and group 4: presence of fluid identified by air-fluid levels with a heterogeneous signal intensity. The ADC of each imaging finding was measured by using a 5-mm area of interest. Statistical differences between the groups were determined by using nonparametric tests with a 5% significance level.

RESULTS

Statistically significant differences were observed between group 1 and the other groups. Mucosal thickening was associated with lower ADC values compared with the other inflammatory lesions.

CONCLUSIONS

The ADC can be useful in differentiating mucosal thickening from other inflammatory alterations in the maxillary sinuses. Mucosal thickening had more restricted water diffusion compared with the other inflammatory lesions.

Diffusion-weighted magnetic resonance imaging of the paranasal sinuses: A systematic review

OBJECTIVES

This was a systematic review of studies on the use of diffusion-weighted imaging (DWI) for paranasal sinus diseases. The applications of DWI were analyzed along with the main results, and conclusions were obtained by the investigators.

STUDY DESIGN

Databases were searched using the keyword "diffusion" combined with "sinonasal," "paranasal sinus," "maxillary sinus," "frontal sinus," "ethmoid sinus," and "sphenoid sinus," including only articles that were published from 2008 to 2018. Only original English language studies with sinonasal disease samples were selected.

RESULTS

Sixteen studies about various sinonasal diseases were included. The main objectives of most of the studies were related to the use of the apparent diffusion coefficient (ADC) in the differentiation of benign lesions and malignant neoplasms. We concluded that the ADC for malignant neoplasms is lower. Histologic features of samples evaluated in the studies were heterogeneous.

CONCLUSIONS

The ADC may improve the quality of the diagnostic hypothesis, particularly in differentiating benign and malignant diseases. Furthermore, the differences between certain types of lesions could be determined by using the ADC. However, further studies focusing on inflammatory diseases should be performed. Overall, DWI and the ADC are promising methods that can be incorporated into routine evaluations.

Diffusion-Weighted Magnetic Resonance Imaging in Maxillary Sinuses Inflammatory Diseases: Report of Three Cases and Literature Review

Background

Magnetic resonance imaging is considered a preferable imaging examination in the diagnosis of inflammatory maxillary sinus disease and can provide precise sinonasal characterization. Diffusion-weighted magnetic resonance imaging and apparent diffusion coefficient are complementary magnetic resonance imaging tools that can be applied to the differentiation of sinus diseases. In this report, 3 cases of inflammatory maxillary sinus diseases imaging findings considering diffusion-weighted magnetic resonance imaging features were described. Additionally, a literature review considering the use of diffusion-weighted magnetic resonance imaging in inflammatory lesions is provided.

Methods

The cases reported were: presence of air-fluid levels, mucosal thickening and a mucous retention cyst. Conventional magnetic resonance imaging and apparent diffusion coefficient (ADC) maps, with ADC values were demonstrated. In the literature review, the studies considering inflammatory lesions were detailed, as well as ADC values established by investigators.

Results

ADC values for presence of air-fluid levels, mucosal thickening and mucous retention cyst were respectively: 1.99 x 10^-3 mm²/s; 1.83 x 10^-3 mm²/s; 2.05 x 10^-3 mm²/s.

Conclusions

It was observed that apparent diffusion coefficient values from the inflammatory lesions described in this report were different and apparent diffusion coefficient may be useful in the differentiation of these maxillary sinus alterations. Further larger sample investigations considering apparent diffusion coefficient values focusing in inflammatory lesions are recommended. The lack of studies considering the use of diffusion-weighted magnetic resonance imaging on inflammatory diseases diagnostic was the major limitation to the literature review.

The added value of pretreatment DW MRI in characterization of salivary glands pathologies

OBJECTIVE

To evaluate the added value of diffusion weighted magnetic resonance imaging (DW-MRI) in characterization of salivary gland lesions.

STUDY DESIGN

A prospective study was carried out between January 2013, and March 2015.

METHODS

The study included 46 patients. The consultant radiologist, who reviewed the scans to comment on the apparent diffusion coefficient (ADC) value and ADC histogram was blind to the suspected pathology. Radiological findings were then compared to clinical and histological findings.

RESULTS

The diagnostic performance of DW-MRI for identification of malignant lesions showed that the sensitivity, specificity, and positive and negative prediction value were 100%, 92%, 91.3%, and 100%, respectively.

CONCLUSION

The specific ability of DW-MRI to probe tissue microstructures is an interesting complement to the currently used imaging procedures in the characterization, and even grading of malignancies. ADC mapping is an easy, cost effective promising tool that has neither radiation exposure, nor amalgam artifacts and can be used in helping characterization of salivary glands lesions.

LEVEL OF EVIDENCE

1B.

Magnetic resonance imaging in sinonasal disease

Computed tomography (CT) is often the primary imaging modality for the evaluation of sinonasal disease. For some indications, magnetic resonance imaging (MRI) may provide additional information. There are established indications for using MRI in complicated sinonasal inflammatory disease, invasive fungal sinus disease, and sinonasal mass lesions. When MRI is used in the evaluation of sinonasal disease, it is usually used as a complementary modality in addition to CT. Magnetic resonance imaging in sinonasal disease can be used to further characterize the primary sinonasal disease process and to evaluate the extent of complications such as orbital or intracranial involvement. When MRI is used in sinonasal disease, it should be evaluated in the context of the clinical situation and CT imaging features. This will help radiologists provide a meaningful differential diagnosis to assist in clinical management.