Toru Chikui

Imaging findings of lipomas in the orofacial region with CT, US, and MRI

OBJECTIVE The aim of this study was to document retrospectively the imaging findings of lipomas with the use of computed tomography, ultrasonography, and magnetic resonance imaging. STUDY DESIGN Thirteen patients with 11 lipomas and 2 lipomatoses were evaluated. Eleven cases were examined by computed tomography, 9 by ultrasonography, and 3 by magnetic resonance imaging. RESULTS Lipomas had a density ranging from -134 to -83 Hounsfield units, (mean-108) on the computed tomography images. The margins were ill defined in 9 of 10 cases. The superficial muscles were displaced externally in 8 cases and internally in 2 cases. With ultrasonography, 8 lesions were hypoechoic, and one was hyperechoic. All three lesions had a high signal intensity on both T1- and T2-weighted images. CONCLUSIONS Lipomas had a specific range of computed tomography Hounsfield unit values and also displaced the surrounding soft tissue. Although some variation in the ultrasonographic appearance was observed, the lesions tended to be hypoechoic. These findings may be useful for diagnosing lipomas in the orofacial region.

THE COMBINED USE OF US AND MR IMAGING FOR THE DIAGNOSIS OF MASSES IN THE PAROTID REGION

Purpose: To evaluate the usefulness of the combination of the two non-invasive modalities US and MR imaging to diagnose masses in the parotid region. Material and Methods: The US and MR findings of 21 patients with parotid masses were analyzed retrospectively by two radiologists without any clinical or histopathological information. The specific points evaluated were location, shape, margin, internal architecture, and intensity level on both US and MR, posterior echo enhancement on US, and capsule-like lining of the tumor on MR. Results: The findings concerning the shape and margin on US and MR were in fairly good agreement. Concerning the findings of the internal architecture, US could reveal the minute structures of the tumor while MR demonstrated differences in the signal intensities of histological tissue types of the various tumors. The posterior echo enhancement on US and the capsule-like lining on MR of the tumors were also useful for the diagnosis. Conclusion: Our results suggest that the combination of US and MR is useful for examining soft tissue masses in the parotid region to make a more accurate diagnosis, and not just differentiate malignant lesions from those which are benign.

Pharmacokinetic analysis based on dynamic contrast-enhanced MRI for evaluating tumor response to preoperative therapy for oral cancer

To evaluate whether a pharmacokinetic analysis is useful for monitoring the response of oral cancer to chemoradiotherapy (CRT).

Clinical Significance of Combined Assessment of the Maximum Standardized Uptake Value of F-18 FDG PET with Nodal Size in the Diagnosis of Cervical Lymph Node Metastasis of Oral Squamous Cell Carcinoma

RATIONALE AND OBJECTIVES This study aimed to elucidate the diagnostic accuracy of F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) for nodal involvement in oral squamous cell carcinoma (OSCC), and to reveal clinically useful factors to distinguish between true-positive (TP) and false-positive (FP) nodes. MATERIALS AND METHODS Thirty-eight patients with primary OSCC who underwent neck dissection were assessed. The diagnostic accuracy of F-18 FDG PET/CT was evaluated, and then compared with that of CT/ultrasonography (US). Furthermore, the association of the maximum standardized uptake value (SUVmax) and nodal size with the histopathologic findings was examined. RESULTS Sensitivity and specificity using F-18 FDG PET/CT were 77.1% and 97.3%, and those using CT/US were 72.9% and 98.9%, respectively. The SUVmax of TP nodes was significantly higher than that of FP nodes. Nodes with SUVmax >4.5 were pathologically confirmed as metastasis. Nodes with SUVmax ≤4.5 were further discriminated between TP and FP nodes by using the long axis diameters or the ratios of long to short axis diameter as clinical parameters. Positive correlation between the SUVmax and the short-axis diameter was found in TP nodes. The AUC obtained from the ROC curves of the SUVmax alone (AUC, 0.804) was improved by combination with the long-axis diameter (AUC, 0.867) or the short-axis diameter (AUC, 0.846), although no significant difference was found. CONCLUSIONS These results indicated that F-18 FDG PET/CT was potentially useful in diagnosing preoperative nodal state. Furthermore, combined assessment of SUVmax with nodal size could be significant in the identification of metastatic lymph nodes in OSCC patients.

Sonographic diagnosis for Mikulicz disease

OBJECTIVE The aim was to investigate the diagnostic imaging characteristics of Mikulicz disease (MD), especially sonographic ones, and to clarify the differences between them and those in Sjögren syndrome (SS), based on new criteria of MD. STUDY DESIGN The sonographic and sialographic images, as well as clinical, histopathologic, and serologic findings of 9 patients satisfying the new criteria of MD were analyzed and compared with those in SS. RESULTS All swollen submandibular glands showed bilateral nodal hypoechoic areas with high vascularization on sonograms and a parenchymal defect on sialograms, whereas parotid glands showed normal or slight change on both images. Nodal areas in submandibular gland sonograms were unclear on computerized tomography and on magnetic resonance imaging, but showed accumulation on gallium scintigraphy. CONCLUSION Mikulicz disease showed a high rate of bilateral nodal change in submandibular glands, which was completely different from SS. For detection and follow-up of these changes, sonography may be the best imaging modality.

Submandibular gland duct endoscopy: Diagnostic value for salivary duct disorders in comparison to conventional radiography, sialography, and ultrasonography

The purpose of this study is to evaluate the usefulness of endoscopy as a procedure for the diagnosis of submandibular gland duct disorders. Endoscopy of the submandibular glands was performed on 12 patients with symptoms of obstructive sialoadenitis to identify the cause of obstruction. The endoscopic findings were then compared to those of diagnostic procedures such as conventional radiography, sialography, and ultrasonography. Six normal subjects also underwent endoscopy to better understand the normal findings of the duct system. Endoscopy demonstrated salivary gland calculus in 5 of 12 patients, which was revealed as filling defects on sialograms and as strongly echogenic structures on ultrasonograms in 4 of the patients. Endoscopy revealed secretion plugs, secretion plaques, and/or stenosis, which could not be seen by any other diagnostic procedures in 5 patients, as the cause of recurrent swelling in all 7 patients not demonstrating sialolith. Abnormal findings of the duct wall such as vasodilatation, fibrosis, edema, or erythema were seen in four patients, three of whom exhibited dilatation of the duct system on sialograms. In four patients, a decreasing internal echo level of the gland was seen on ultrasonograms. Our initial results for submandibular gland duct endoscopy thus appear to be promising.

Mucoepidermoid carcinoma in the mandible: Findings of panoramic radiography and computed tomography

Six patients with mucoepidermoid carcinoma in the mandible were studied with both panoramic radiography and computed tomography. Lesion shape and margin were evaluated on panoramic radiography, and bony expansion and cortical plate destruction were evaluated on computed tomography. In addition, a possible correlation among radiographic findings, histologic findings, and prognosis was investigated. Lesions found on panoramic radiography were classified into three types; each type pertained to two of the six patients. The lesion types were as follows: cystic, characterized by a large, cystic radiolucent area; rarefying, characterized by rarefying changes of the trabeculae; and infiltrative, characterized by a central ill-defined area of bony destruction. The results show that computed tomography is useful in the identification of tumor extent, bony expansion, and cortical plate destruction resulting from tumors. None of the patients whose lesions were of the cystic or rarefying type showed evidence of disease after surgery. In contrast, both of the patients whose lesions were of the infiltrative type died of their tumors. Histologic findings of the cystic and rarefying types showed tumors that were well-differentiated or moderately well-differentiated, whereas findings of the infiltrative type showed poorly differentiated tumors. Radiographic findings correlated with histologic findings and prognosis of mucoepidermoid carcinoma in the mandible in this limited series.

The Principal of Dynamic Contrast Enhanced MRI, the Method of Pharmacokinetic Analysis, and Its Application in the Head and Neck Region

Many researchers have established the utility of the dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) in the differential diagnosis in the head and neck region, especially in the salivary gland tumors. The subjective assessment of the pattern of the time-intensity curve (TIC) or the simple quantification of the TIC, such as the time to peak enhancement (T peak) and the wash-out ratio (WR), is commonly used. Although the semiquantitative evaluations described above have been widely applied, they do not provide information on the underlying pharmacokinetic analysis in tissue. The quantification of DCE-MRI is preferable; therefore, many compartment model analyses have been proposed. The Toft and Kermode (TK) model is one of the most popular compartment models, which provide information about the influx forward volume transfer constant from plasma into the extravascular-extracellular space (EES) and the fractional volume of EES per unit volume of tissue is used in many clinical studies. This paper will introduce the method of pharmacokinetic analysis and also describe the clinical application of this technique in the head and neck region.

Imaging findings of neurogenic tumours in the head and neck region

OBJECTIVE The aim of this study was to describe the CT, MRI and ultrasonography findings of five cases of neurogenic tumours in the head and neck region. METHODS Five neurogenic tumours were analysed with respect to their CT value, the presence of cystic change, target sign, lobulation, connection to the nerve and vascularity. RESULTS The contrast-enhanced CT (ECT) of the schwannomas demonstrated either a mass with low enhancement (two out of three cases), which reflected the predominant Antoni B components, or a mass with cystic changes, which was an Antoni A-based schwannoma displaying cystic changes (one out of three cases). On MRI, all tumours showed homogeneous and isointense signals for muscle on T₁ weighted images (T₁ WIs). T₂ weighted images (T₂ WIs) and gadolinium (Gd)-enhanced T₁ WIs demonstrated target sign in both schwannomas. Ultrasound examination showed a well-defined, ovoid or round hypoechoic mass. The direct connection to the nerve was demonstrated in two of the five cases. Lobulation was observed in only one of the five cases and cystic changes were observed in one of the five cases. In all of the cases, no vascularity was seen in power Doppler images (PDIs) obtained percutaneously. CONCLUSIONS Low-enhanced areas on ECTs can be specific for schwannomas, which suggests the predominance of Antoni B components. The target sign on T₂ WIs and Gd-enhanced T₁ WIs can be specific, which can be used to differentiate the two different components (Antoni A and Antoni B). The direct connection to the nerve can be a specific finding for neurogenic tumours; however, at present the sensitivity is 40%.

A Quantitative Analysis of Sonographic Images of the Salivary Gland: A Comparison Between Sonographic and Sialographic Findings

We performed three quantitative analyses (particle analysis, fractional Brownian motion [fBM] model analysis, two-dimensional [2-D] fractal analysis) of the ultrasonographic (US) images of the salivary gland and evaluated whether the obtained indices correlated with the sialographic stage of Rubin-Holt. Our study included 192 patients suspected of having Sjögrens syndrome (SS). In 89 patients, sialography demonstrated abnormal findings. Based on a particle analysis, we calculated both the average size of the particles (avg-area) and the area ratio to evaluate the presence of hypoechoic areas and echogenic lines, which are characteristic of SS. According to the fBM model, we calculated the Hurst index of the original image (Hurst-ori) and the background-subtracted image (Hurst-bs) to evaluate the complexity of the pixel value distribution. We also obtained the 2-D fractal dimension (2-D-FD) to evaluate the complexity of the contour lines. We entered these indices of the parotid glands (PG) into a logistic regression analysis and evaluated which indices were useful predictors for detecting an abnormal sialographic stage. Significant differences were observed between the normal and abnormal groups in all five indices of the PG (Mann-Whitney U test) and all five indices were correlated with the Rubin-Holt stage (Spearmans Rank Correlation Test). As the Rubin-Holt stage became more severe, both the Hurst-ori and 2-D-FD became smaller. Alternatively, the Hurst-bs, avg-area, and area ratio became higher. Three indices (avg-area, area ratio and Hurst-ori) were selected as useful predictors for detecting abnormal sialographic stages. This quantitative analysis system is therefore considered to have potentially useful clinical applications for the detection of abnormal sialographic findings.