Yukio Sugai

CT detection of facial canal dehiscence and semicircular canal fistula : Comparison with surgical findings

OBJECTIVE The purpose of this study was to determine the accuracy of high resolution CT (HRCT) in the detection of facial canal dehiscence and semicircular canal fistula, the preoperative evaluation of both of which is clinically very important for ear surgery. MATERIALS AND METHODS We retrospectively reviewed the HRCT findings in 61 patients who underwent mastoidectomy at Yamagata University between 1989 and 1993. The HRCT images were obtained in the axial and semicoronal planes using 1 mm slice thickness and 1 mm intersection gap. RESULTS In 46 (75%) of the 61 patients, the HRCT image-based assessment of the facial canal dehiscence coincided with the surgical findings. The data for the facial canal revealed sensitivity of 66% and specificity of 84%. For semicircular canal fistula, in 59 (97%) of the 61 patients, the HRCT image-based assessment and the surgical findings coincided. The image-based assessment in the remaining two patients, who both had massive cholesteatoma, was false-positive. CONCLUSION HRCT is useful in the diagnosis of facial canal dehiscence and labyrinthine fistula, but its limitations should also be recognized.

Clinical assessment of hepatic functional reserve using99mTc DTPA galactosyl human serum albumin SPECT to prognosticate chronic hepatic diseases —Validation of the use of SPECT and a new indicator—

Rationale: It is generally known that scintigraphy of99mTc diethylenetriamine pentaacetic acidgalactosyl human serum albumin (99mTc-GSA) is useful for assessing hepatic functional reserve. For hepatic functional indicators, the index of the calculated planar image has been used in previous studies. However, there have been few reports that suggest that the indicators calculated from static SPECT data would be useful for the assessment of hepatic function. The aims of this study were to establish a simple method for assessing hepatic functional reserve using the liver SPECT of99mTc-GSA and to apply this method for rich stratification in patients with chronic hepatic diseases.Methods: A liver phantom (a 50% concentration of99mTc solution) was used to compare the planar and SPECT methods. According to the definition of the new indicator, the liver SPECT of99mTc-GSA was divided by a syringe SPECT of99mTc-GSA and was called the liver uptake ratio (LUR). We correlated the LUR and the liver uptake ratio calculated according to the blood-sampling method.99mTc-GSA SPECT was performed in 137 patients with hepatic diseases, including chronic hepatic diseases, and 20 healthy volunteers. The LUR was correlated between the formed subtypes for all subjects.Results: The acquired phantom-count ratio calculated by the SPECT method was more accurate than that acquired by the planar method. A good correlation was obtained between the LUR and the blood-sampling method (r=0.971). The LUR was significantly lower in subjects with severe cirrhosis than in healthy subjects or those with chronic hepatitis and mild cirrhosis, and it was significantly lower in subjects with chronic hepatitis and mild cirrhosis than in healthy subjects. The LUR was significantly correlated with other hepatic function tests. Based on LUR, the chronic hepatic diseases were divided into two groups: Group A, with LURs 30% and higher, and Group B, with LURs below 30%. An LUR of 30% marked the 25th percentile of the mildcirrhosis group. The cumulative survival rates were lower in Group B than in Group A.Conclusion: The SPECT method was superior to the planar method for assessing LURs. LUR was a suitable inducator of99mTc-GSA clearance from the blood pool and of binding to the asialo-glycoprotein receptor. LUR is a simple and clinically useful indicator for the assessment of hepatic functional reserve in chronic hepatic diseases.

Abducens nerve enhancement demonstrated by multiplanar reconstruction of contrast-enhanced three-dimensional MRI

Abstract We describe contrast enhancement of the cisternal portion of the abducens nerve and discuss its clinical significance. We examined 67 patients with ophthalmoplegia using contrast-enhanced 3-dimensional (3D) MRI with multiplanar reconstruction along the nerves and found 16 patients (ten men, six women), aged 10–73 years (mean 34.4 years), with contrast enhancement of the abducens nerve. Of the 36 patients who had an abducens palsy, 14 (39 %) showed contrast enhancement. In the 16 patients, 23 abducens nerves enhanced; 13 were symptomatic and 10 asymptomatic at the time. The causes were disseminated tumour (1), an inflammatory process (3), trauma (2), ischaemia (2) and autoimmune diseases (8), such as the Miller Fisher syndrome, acute ophthalmoparesis, polyneuropathy and multiple sclerosis. Abducens and/or oculomotor nerve enhancement was the only abnormality on MRI in the patients with traumatic or ischaemic neuropathy or autoimmune diseases. There were 14 patients who recovered fully within 1–6 months after treatment, and resolution of the enhancement correlated well with recovery.

Diagnosis of the Ossicular Chain in the Middle Ear by High-Resolution CT

This study was conducted to assess the usefulness and limitation of high-resolution CT for evaluating the condition of ossicular chain in the middle ear. Preoperative CT findings of the ossicular chain were compared with the operative findings of ossicles in 26 patients with chronic otitis media or congenital ossicular anomaly who underwent tympanoplasty. Total defect of head of the malleus, body of the incus and long process of the incus were completely detected by high-resolution CT. But the reliability in detecting the defect of handle of the malleus and superstructure of the stapes were 33.3% and 60%, respectively. Defect of the I-S joint (1 case) and partial defect of stapes crus (2 cases) could not be diagnosed correctly in the preoperative estimation. Although these findings demonstrate the limitations of high-resolution CT in the diagnosis of ossicular chain, it will be diminished by the advanced space resolution of CT in the future.

High-resolution computed tomography using multiplanar reconstruction for the facial nerve canal.

Multiplanar reconstruction (MPR) images along the facial nerve canal were prepared with high-resolution computed tomography (HRCT) and their clinical usefulness was evaluated. Over a period of 6 years, temporal bone HRCT was performed on 628 cases. Of these cases, 6 patients exhibited facial nerve lesions, including facial nerve schwannoma ( n =3), traumatic facial nerve palsy ( n =2) and congenital facial nerve palsy ( n =1). Thirty patients without facial nerve lesions, such as chronic otitis media, were randomly selected as controls. Two types of MPR image were composed. One was along the labyrinthine and tympanic segment, and the other was along the tympanic and mastoid segment. Other MPR images, such as those along the facial nerve canal and bone fracture line, were composed as needed. All MPR images were prepared with real-time observation of delicate angles. In all cases, MPR images delineated the labyrinthine and tympanic segment in one image, and the tympanic and mastoid segment in another image. In two patients with traumatic facial nerve palsy, the MPR images revealed a relationship between the facial nerve canal and the bone fracture. In conclusion, MPR images of the facial nerve canal are easy to obtain and are useful in detecting facial nerve schwannoma, traumatic facial nerve palsy and congenital facial nerve palsy.

Development of “super rapid dynamic SPECT,” and analysis of retention process of99mTc-ECD in ischemie lesions: Comparative study with133Xe SPECT

To analyze the retention process of technetium-99m ethyl cysteinate dimer (99mTc-ECD) in normal and ischemic lesions, we developed a super rapid dynamic SPECT system based on the CERASPECT (DSI, Inc., Waltham, MA, USA). The system made it possible to take a SPECT series every 2 seconds. Each SPECT series contains a maximum of 16 slices (6.6 mm slice interval) in a matrix size of 32 ? 32. The sensitivity of this system is 175 kcps/MBq/ml/cm slice thickness, and resolution is 12 mm FWHM at the center of a 20x0444; water phantom.Using the super rapid SPECT system, the kinetic behavior of the99mTc-ECD during retention in normal and ischemie lesions was analyzed. Twenty patients with ischemie lesions that were clearly demonstrated by133Xe-rCBF (regional cerebral blood flow) SPECT but unclear on static “Tc-ECD SPECT were examined. For the dynamic SPECT, 700 MBq of ““Tc-ECD was injected intravenously, and dynamic SPECT data were acquired every 2 seconds during a 90-second period. The serial dynamic SPECT and time-activity curves at some lesions with reduced rCBF and at the contralateral normal brain were analyzed. These dynamic SPECT data were compared with conventional static99mTc-ECD SPECT and quantitative133Xe-rCBF SPECT.All of mildly or moderately reduced rCBF lesions on the133Xe-rCBF SPECT were recognized as low activity regions only at the early phase (during about 2-20 sec or less), with the lesions then gradually vanishing. These lesions were not recognized on the conventional static SPECT taken after the dynamic study. The time-activity curve at the reduced rCBF lesion was lower than that of contralateral normal brain at the early phase, and overtook the activity in the normal region with a gradual increase.The early phase images of99mTc-ECD SPECT within 20 seconds by the super rapid dynamic SPECT were very useful to the same extent as the133Xe-rCBF SPECT for detecting mild or moderate ischemie lesions.This study suggests that esterase activity, participating in the ECD retention mechanism, may be tolerable to mild or moderate ischemia. This tolerance may be the main cause of the nonlinear relationship between ECD accumulation and cerebral blood flow.

Visualization of the Trochlear Nerve in the Cistern with Use of High-Resolution Turbo Spin-Echo Multisection Motion-Sensitized Driven Equilibrium

BACKGROUND AND PURPOSE: The trochlear nerve is so thin that it is rarely observed with MR imaging. Therefore, we used high-resolution MSDE to reliably visualize the cisternal segments of the trochlear nerve. MATERIALS AND METHODS: Participants were 10 healthy young adults (mean age, 24 years), and 20 trochlear nerves were examined. HR-MRC, BS-MRC, and HR-MSDE were performed. A neuroradiologist judged the visibility of the trochlear nerves as 1 of 4 grades (“Excellent,” “Good,” “Fair,” and “Not”) in each MR imaging sequence. The findings were then statistically analyzed with the χ2 test. RESULTS: Of all 20 trochlear nerves, 6 with HR-MRC, 13 with BS-MRC, and 18 with HR-MSDE were judged as “Excellent.” CSF flow-related artifacts and vessels in the cistern and cerebellar tentorium in HR-MRC tended to prevent the neuroradiologists from identifying the trochlear nerve. Vessels in the cistern and cerebellar tentorium in BS-MRC also tended to prevent the neuroradiologists from identifying the trochlear nerve. Compared with other sequences, HR-MSDE visualized the trochlear nerve more often. The χ2 test revealed statistically significant differences among the 3 MR imaging sequences (P < .01). The scan time of HR-MSDE was approximately 1.5–2.2 times longer than that of the other sequences. CONCLUSIONS: HR-MSDE is able to clearly visualize the trochlear nerve and has the same or better ability to delineate the trochlear nerve compared with other MR imaging sequences, though its long scan time does not yet yield practical use.

Radiological Image Features of the Atypical Teratoid/Rhabdoid Tumor in Adults: A Systematic Review

PurposeAtypical teratoid/rhabdoid tumor (AT/RT) occurs in children less than 3 years old, and has a very poor prognosis. AT/RT seldom occurs in adult. We have experienced four cases of AT/RT at our institute. The purpose of this study is to evaluate the radiological image findings of adult-onset AT/RT and to conduct a systematic review.MethodsImage findings of four AT/RTs in our institute were retrospectively evaluated by an experienced neuroradiologist. If the images were unavailable, image findings were evaluated from the former image interpretation report. We assembled papers of adult-onset AT/RT (n = 38) and evaluated the image findings.ResultsAT/RT occurs in a variety of sites (spinal region, pineal region, suprasellar region, jugular foramen, and so on). High density on computed tomography (CT) was seen in 10 of 11 cases; mixed intensity in T2-weighted image was seen in 13 of 18 cases; and high intensity on diffusion-weighted image (DWI) was seen in 3 of 3 cases. Contrast enhancement was observed in all cases in which images were available.ConclusionsWe have experienced four adult-onset AT/RT cases at our institute and have evaluated image findings through systematic review. The image findings of high density on CT, high intensity on DWI, with low apparent diffusion coefficient, and a heterogenous component should lead to an inclusion of AT/RT in the differential diagnosis of a tumor; these findings may be able to suggest AT/RT; however, they cannot make the diagnosis.

Focal deformity of the cranial nerves observed on multislice motion-sensitized driven equilibrium (MSDE) in patients with neurovascular compression.

Objective Our purpose is to demonstrate the deformity of the cranial nerves by arterial compression using a novel technique, multislice motion-sensitized driven equilibrium (MSDE). Methods Subjects were 10 patients with neurovascular compression (5 patients with trigeminal neuralgia and 5 patients with hemifacial spasm). We observed the existence and extent of deformity of nerves by MSDE. Afterward, we compared operative findings with preoperative imaging findings and evaluated the validity of the latter. Results All compressing, blood vessels could be correctly identified through preoperative evaluation. Of all patients, 7 showed deformity of the cranial nerves, which was consistent with operative findings except in one case. In postoperative evaluation, patients’ neurological symptoms improved and the deformity disappeared. Three patients did not show deformity on preoperative MSDE images. In these patients, neural compression was also not observed during the operation. Conclusions The deformity of cranial nerves in patients with neurovascular compression was clearly shown using MSDE. Abbreviation CT - computed tomography IVH - intraventricular hemorrhage ICH - intracerebral hemorrhage DICOM - Digital Imaging and Communications in Medicine DSI - dice statistical index CLEAR-IVH - Clot Lysis Evaluating Accelerated Resolution of Intraventricular Hemorrhage Trial GT_Vol - ground truth volume Seg_Vol - segmented volume min - minimum max - maximum

Characteristics of three cases of hepatocellular carcinoma showing enhanced technetium‐99m‐diethylenetriaminepentaacetic acid‐galactosyl human serum albumin accumulation by single photon emission computed tomography analysis

Background:  The asialoglycoprotein receptor (ASGP‐R) is abundantly expressed on the sinusoidal surfaces of hepatocytes. However, the majority of hepatocellular carcinomas (HCC) lack ASGP‐R on their cell surface membranes. We describe three cases of HCC showing increased expression of ASGP‐R in comparison with the surrounding liver tissue.