Mitsuomi Matsumoto

Characteristic bright signal of parotid pleomorphic adenomas on T2-weighted MR images with pathological correlation

The purpose of this study was to correlate the MR features and histological findings of pleomorphic adenomas, which are the most common tumour of the parotid gland, and to distinguish them from other types of tumour in the parotid gland. The materials studied consisted of 20 pleomorphic adenomas, including 12 untreated and eight recurrent cases, 17 other benign parotid tumours, and 12 malignant tumours. T1- and T2-weighted images and Gd-DTPA enhanced T1-weighted images were obtained. Characteristic bright signals with a higher intensity than that of CSF were seen in all of the pleomorphic adenomas on T2-weighted images, and were found to represent myxoid areas histologically. Although the cystic spaces in some benign tumours produced bright signals, these areas were distinguished from myxoid areas due to nonenhancement with Gd-DTPA. No bright signals were seen in the malignant tumours. In conclusion, bright signals on T2-weighted images represent myxoid tissue and are useful findings for diagnosing pleomorphic adenomas.

Image processing for computer‐aided diagnosis of lung cancer by CT (LSCT)

This paper reports a special-purpose CT for early detection of lung cancer and presents the basic idea. The parallel use of the following two systems is investigated as the diagnosis-support image display method needed in such a system, and a satisfactory result is obtained. (1) The maximum intensity projection (MIP) is applied as a means to realize the two-dimensional projection display from the three-dimensional information composed of 40 slices of lung tissue while retaining the information concerning the pathological shadows. When the simple MIP is applied, there is a large disturbance due to unnecessary organ signals. Consequently, a method is developed in which unnecessary information is deleted by thresholding; (2) The automatic recognition of candidates for the pathological shadows is applied to each slice. Only the CT image containing a shadow candidate is displayed on CRT, which helps to reduce greatly the number of cross sections to be displayed. In the automatic recognition of the pathological shadow, the quoit filter recently developed by the authors is employed.

Image processing for computer-aided diagnosis of lung cancer screening system by CT (LSCT)

In this paper, we report the image processing technique for computer-aided diagnosis of lung cancer screening system by CT (LSCT). LSCT is the newly developed mobile-type CT scanner for the mass screening of lung cancer by our project team. In this new LSCT system, one essential problem is the increase of image information to be diagnosed by a doctor to about 30 slices per patient from 1 X-ray film. To solve this difficult problem, we are trying to reduce the image information drastically to be displayed for the detector by image processing techniques. We propose a new method named Variable-New-Quoit filter for the automatic recognition of the pathological shadow candidates. Our computer aided diagnosis system can satisfactorily reduce the number of CT cross sections by this method, containing the abnormal shadow candidates.

Quoit filter-a new filter based on mathematical morphology to extract the isolated shadow, and its application to automatic detection of lung cancer in X-ray CT

We propose a new algorithm named Quoit filter (Q-filter) to extract the isolated but low amplitude shadow located in the background which has extremely high amplitude fluctuation. Q-filter is a kind of mathematical morphology and its formulation is quite simple. This simplicity brings about a unique merit that output from this filter is analytically expressive for the case of analytical input shapes like ball, cone, or rotation of cosine function, which have characteristics of rotation symmetry and monotonic decreasing from the origin. This Q-filter is composed of two sequential operations named Q Trans. and Q Inv. Trans., Q Trans. corresponds to extracting feature parameters like a matched filter from the input image having a nonideal isolated shadow, and Q Inv. Trans. corresponds to restoring isolated images using extracted feature parameters. This filter is applied to detecting the cancer candidate shadow automatically in the CT cross sections of lung areas, aiming to reduce drastically the number of cross sections to be diagnosed by the doctor.

MR detectability of posterior pituitary high signal and direction of frequency encoding gradient

The reported rate of detection of the posterior pituitary high signal (PPHS) in Tl-weighted MR images has varied. The purpose of this study was to clarify the influence of the direction of the chemical shift on the detectability of the PPHS. Fifty-three subjects with a normal pituitary gland (n = 41) or an empty sella (n = 12) were studied with sagittal Tl-weighted spin-echo imaging using two or three different frequency encoding gradient (FEG) directions: caudocephalad (FEG: CH), cephalocaudad (FEG: HC), and anteroposterior (FEG: AP). The PPHS was detected and clearly separated from the high signal of the fatty marrow of the dorsum sellae in 54% of the normal pituitary gland and 25% of the empty sella cases with FEG: CH, and in none of the cases (n = 5) with FEG: HC. The chemical shift of the fatty marrow in the dorsum sellae tended to overshadow the PPHS when FEG: CH and HC were used. In contrast, when FEG: AP was used, the PPHS was clearly separated from the dorsum sella marrow fat in all cases. Frequency encoding gradient: AP represents the optimal setting for evaluating the posterior pituitary gland.

Serial MR intensity changes of the posterior pituitary in a patient with anorexia nervosa, high serum ADH, and oliguria

The posterior pituitary high signal (PPHS) seen on MRI of the sella in normal individuals probably reflects antidiuretic hormone (ADH) granules stored in the posterior pituitary lobe (PPL). We present a case with anorexia nervosa, high serum ADH, and oliguria who underwent three cerebral MR studies over the course of treatment. The first MR examination showed absence of PPHS and early enhancement of the PPL on dynamic MRI. In subsequent MR examinations PPHS became evident in concomitance with clinical improvement. This case suggests that PPHS changes may reflect reaccumulation of ADH granules and that dynamic MR of the PPL may be useful for assessing the vascularity of the PPL and/or the reversibility of its function.

Image processing for computer-aided diagnosis of lung cancer by CT(LSCT)

This paper reports the image processing technique for computer-aided diagnosis of lung cancer by CT(LSCT). LSCT is the newly developed mobile-type CT scanner for the mass screening of lung cancer by our project team. In this new LSCT system, one essential problem is the increase of image information to about 30 slices per person from 1 X-ray film. To solve this difficult problem, we tried to reduce the image information drastically to be displayed for the doctor, by image processing techniques.

A Recognition Method of Lung Nodule Shadows in X-Ray CT Images Using 3D Object Models

In this paper, we describe a recognition method of lung nodule shadows in X-ray CT images using 3-dimensional nodule and blood vessel models. From these 3D object models, artificial CT images are generated as templates. The templates are then applied to input images which comprise of suspicious shadows. If any parameters of the suspicious shadow matches a nodule template rather than any blood vessel template, then it is determined to be abnormal. Otherwise, it is determined to be normal. By applying our new method to the actual lung CT images of 38 patients, the false positive ratio is reduced to 4.31 [shadow/patient] with the sensitivity exceeding 95%.

Transient unilateral reverse ventilation/perfusion mismatch in a patient with lung cancer.

The authors report a transient, unilateral reverse ventilation/perfusion (V/P) mismatch in a patient with squamous cell lung cancer. The right lung was well perfused but not ventilated (unilateral reverse V/P mismatch). However, lung imaging performed 3 days later demonstrated the absence of both perfusinon and ventilation (V/P match). Reverse V/P mismatch may be a transient process.

Bilateral breast uptake of Tl-201 chloride in a nursing woman

A 35-year-old woman with a 10-month-old infant was evaluated with pulmonary SPECT using Tl-201 chloride to assess the probability of malignant liver for a pulmonary nodule in left upper lobe. No increased Tl-201 uptake in her pulmonary lesion was found. However, there was bilateral breast uptake on early images. This uptake diminished by approximately 50% on delayed images without excretion of milk from the breasts. Tl-201 breast uptake in a nursing woman might be caused by diffusion of Tl-201 into the extravascular space, and the mechanism appears to be different from Ga-67 citrate breast uptake in a nursing woman.