Development of a medical-text parsing algorithm based on character adjacent probability distribution for Japanese radiology reports.

OBJECTIVES: The objectives of this study were to investigate the transitional probability distribution of medical term boundaries between characters and to develop a parsing algorithm specifically for medical texts. METHODS: Medical terms in Japanese computed tomography (CT) reports were identified using the ChaSen morphological analysis system. MeSH-based medical terms (51,385 entries), obtained from the metathesaurus in the Unified Medical Language System (UMLS, 2005AA), were added as a medical dictionary for ChaSen. A radiographer corrected the set of results containing 300 parsed CT reports. In addition, two radiologists checked the medical term parsing of 200 CT sentences. RESULTS: We obtained modified inter-annotator agreement scores for the text corrected by the radiologists. We retrieved the transitional probability as the conditional probability of a uni-gram, bi-gram, and tri-gram. The highest transitional probability P(Ci | Ci- 2(*)Ci- 1) was 1.00. For an example of anatomical location, the term "pulmonary hilum" was parsed as a tri-gram. CONCLUSIONS: Retrieval of transitional probability will improve the accuracy of parsing compound medical terms.

Effect of temporary hepatic venous occlusion on hepatic arterial embolization. An experimental study.

RATIONALE AND OBJECTIVES: The authors evaluated the effect of hepatic venous occlusion on hepatic arterial embolization in rats. METHODS: A Lipiodol-Iopamidol mixture was injected into the proper hepatic artery in rats during clamping the right side of the hepatic venous confluence. The distribution of Lipiodol-Iopamidol mixture in the sinusoids was analyzed by histological examination with en bloc silver impregnation. The extent of the distribution of Lipiodol-Iopamidol mixture was compared in sinusoids with hepatic venous occlusion and in sinusoids without hepatic venous occlusion. RESULTS: Lipiodol-Iopamidol mixture was more widely distributed in the lobules with hepatic venous occlusion than in the lobules without occlusion. CONCLUSIONS: Hepatic venous occlusion may enhance the effect of hepatic arterial embolization using Lipiodol emulsions and could be useful in the treatment of hepatocellular carcinoma.

MR imaging of the brain in lymphomatoid granulomatosis.

BACKGROUND AND PURPOSE: Clinical diagnosis of lymphomatoid granulomatosis (LG) of the brain, in patients without skin or chest lesions, usually is difficult because of the nonspecific neurologic manifestations, laboratory data, and CT appearance. Our aim was to characterize the MR appearance of LG of the brain. METHODS: We retrospectively reviewed the MR images in four patients (35 to 72 years old) with histologically confirmed LG of the brain. RESULTS: On T2-weighted images, we noted diffuse hyperintense lesions in the cerebral white matter bilaterally (n = 3), in the brain stem and cerebellar hemisphere (n = 1), and patchy hyperintense lesions the brain stem (n = 2). On contrast-enhanced T1-weighted images, we observed multiple punctate or linear enhancements residing along the perivascular space (n = 4), nodular enhancements (n = 2), ringlike enhancements (n = 1), and a large, enhanced mass (n = 1). All patients had multifocal lesions. CONCLUSION: Although the MR appearance of LG of the brain varies, multiple punctate or linear enhancements that reside along the perivascular space suggest LG.

MR findings in spinal hemangioblastoma: correlation with symptoms and with angiographic and surgical findings.

BACKGROUND AND PURPOSE: To our knowledge, a detailed analysis of MR findings in spinal hemangioblastoma has not been conducted to date. Our purpose was to elucidate the MR features of this disease with special attention to tumor size, correlation with MR findings and clinical symptoms, and any differences between patients with and without von Hippel-Lindau disease (VHLD). METHODS: MR images in five patients with VHLD and seven patients without VHLD were reviewed retrospectively for spinal hemangioblastoma by two neuroradiologists. The MR findings were correlated with clinical symptoms and with angiographic and surgical findings. RESULTS: The MR features depended on the size of the spinal hemangioblastoma. Small (10 mm or less) hemangioblastomas were mostly isointense on T1-weighted images, hyperintense on T2-weighted images, and showed homogeneous enhancement. Larger hemangioblastomas tended to be hypointense or mixed hypo- and isointense on T1-weighted images, heterogeneous on T2-weighted images, and tended to show heterogeneous enhancement. Small hemangioblastomas were located at the surface of the spinal cord, most frequently along its posterior aspect. These were subpial in location at surgery and showed well-demarcated, intense enhancement. Symptomatic small hemangioblastomas had relatively large associated syringes, whereas asymptomatic ones did not. A hemangioblastoma larger than 24 mm was invariably accompanied by vascular flow voids. There was no difference in the MR findings between the two patient groups except for the multiplicity and higher percentage of small tumors in patients with VHLD. CONCLUSION: Knowledge of these MR features helps to differentiate spinal hemangioblastoma from other diseases that show enhancing nodules.

Gd-DTPA-enhanced MR imaging of injured spinal cord.

We retrospectively reviewed 15 gadolinium-enhanced magnetic resonance imaging examinations of the cervical spine in eight patients who had spinal cord injury. Enhancement was demonstrated at the periphery of the intramedullary lesion in three patients at 1 to 14 weeks after injury. The enhancement might reflect vascularized granulation in a reparative phase. Spinal cord injury should be considered in the differential diagnosis of enhanced intramedullary spinal cord lesions.

Telephone line transfer using a local filing system in Hokkaido.

An image-data transfer system using a public telephone line has been constructed between Hokkaido University Hospital (HUH) and Nakashibetsu Town Hospital (NTH). The latter is situated about 420 km from Sapporo and does not have full-time radiologists. A local filing system coupled with a film reader and an optical disk had been installed in HUH in 1986, and in NTH in 1988. Both systems were connected by a public telephone line along which the transfer speed is 9600 bps. Images originating at NTH, mostly CT, were digitized by the film reader and sent to HUH after compression at a ratio of about 5:1 to 10:1. Clinical information concerning a patient was also sent to HUH using facsimile. Radiologists interpreted the transferred data (12 CT images on a film) on the CRT and sent back a written report to NTH using facsimile. The system and its image quality are largely acceptable, especially in an emergency case for brain and abdomen, although the transfer of a film takes about 7 to 20 min.

A hospital-wide PACS: 7 year experience and new development.

Hokkaido university picture archiving and communication system (HU-PACS) began clinical service in the Hokkaido university hospital in 1989. For the first 5 years the service was limited to the radiology department and the outpatient clinics. This paper describes the outline of the HU-PACS, how we have extended the service to all wards and managed the increasing image data accompanied by the installation of new CTs and MRI since 1994. A plan of future HU-PACS is also described.

Clinical experience of Hokkaido University-PACS and FCR-angiography.

Three years' experience with Hokkaido University-PACS (HU-PACS) is reported. In particular, this paper describes the suitability of FCR-angiography for HU-PACS, which has been in clinical use since March 1991. Image quality of FCR-arteriograms was evaluated in the head-and-face region and the abdominal region independently. The image quality in both regions was excellent. Quality of transferred images to image workstation for HU-PACS with 10:1 data compression was also evaluated, and no appreciable image degradation or loss of information was found in the transferred images. There was no significant difference in the examination time required for one patient in abdominal angiography between conventional angiography and FCR-angiography. In summary, FCR-angiography is suitable for HU-PACS as its image acquisition modality.

[Neuroimaging findings in intravascular malignant lymphomatosis].

We reviewed the neuroimaging studies of five patients with intravascular malignant lymphomatosis (IML). All five patients had cerebral symptoms and three had spinal cord or root symptoms. Initial brain CTs, in two patients at the onset of cerebral symptoms, were normal. Brain MR imaging, conducted in four patients during the course of IML, showed multiple white matter lesions which were hyperintense on T2-weighted images. Some of the lesions involved cerebral cortices, and some had mass effect. Serial MR imaging was performed in three patients, and the lesions decreased in size during steroid or CHOP therapy. Gd-DTPA-enhanced study which was conducted in one patient demonstrated enhancement of the white matter lesions. Review of the literature revealed various CT or MR findings; single or multiple cortical or subcortical lesions with or without mass effect, periventricular lesions, and spinal cord lesions. Lesions may or may not be enhanced. Because neuroimaging findings are non-specific, correct diagnosis is difficult to make by imaging studies alone. One should always consider the possibility of IML in the interpretation of radiological images.

Differential diagnosis of hyperintense cerebrospinal fluid on fluid-attenuated inversion recovery images of the brain. Part I: pathological conditions.

The fluid-attenuated inversion recovery imaging sequence is a widely used MRI sequence of the brain. It is an inversion recovery pulse sequence, designed to suppress signals from the cerebrospinal fluid. It is highly sensitive in detection of lesions adjacent to or within the cerebrospinal fluid associated with T(2) prolongation or T(1) shortening. The term "hyperintense cerebrospinal fluid" is used to describe failed suppression, or hyperintensity, of cerebrospinal fluid on fluid-attenuated inversion recovery imaging of the brain. It is often encountered in many important pathological conditions, including subarachnoid haemorrhage, meningitis and leptomeningeal metastasis. However, certain non-pathological states in which there is no definite cerebrospinal fluid abnormality can also present with hyperintense cerebrospinal fluid. Correct interpretation of abnormalities is important to arrive at an appropriate diagnosis. This pictorial review provides fluid-attenuated inversion recovery images of hyperintense cerebrospinal fluid of the brain and describes distinguishing features. Part I features pathological conditions whereas Part II focuses on non-pathological conditions.

Differential diagnosis of hyperintense cerebrospinal fluid on fluid-attenuated inversion recovery images of the brain. Part II: non-pathological conditions.

The fluid-attenuated inversion recovery imaging sequence is a widely used MRI sequence of the brain. It is an inversion recovery pulse sequence, designed to suppress signals from the cerebrospinal fluid. It is highly sensitive for detection of lesions adjacent to or within the cerebrospinal fluid, associated with T(2) prolongation or T(1) shortening. The term "hyperintense cerebrospinal fluid" is used to describe failed suppression or hyperintensity of cerebrospinal fluid on fluid-attenuated inversion recovery imaging of the brain. It is often encountered in many important pathological conditions, including subarachnoid haemorrhage, meningitis and leptomeningeal metastasis. However, certain non-pathological states in which there is no definite cerebrospinal fluid abnormality can also present with hyperintense cerebrospinal fluid. Correct interpretation of abnormalities is important to arrive at an appropriate diagnosis. This pictorial review provides fluid-attenuated inversion recovery images of hyperintense cerebrospinal fluid of the brain and describes distinguishing features, focusing on non-pathological conditions.

Nonenhancing primary central nervous system lymphoma.

Primary central nervous system lymphoma (PCNSL) is rare, although its frequency has increased in recent years. Radiographically, almost all PCNSL enhance on CT and/or MRI, and nonenhancing PCNSL has been thought to be extremely rare. We present PCNSL showing multiple nonenhancing lesions on MRI in an immunocompetent patient.

MRI of wallerian degeneration of the injured spinal cord.

OBJECTIVE: We assessed the MR appearance of wallerian degeneration following spinal cord injury. MATERIALS AND METHODS: We retrospectively reviewed the MR examinations of 13 patients with spinal cord injury. Thirty-one MR examinations were performed at various time intervals (1 day to 4 years) following injury. RESULTS: High signal intensity was observed in six patients (11 examinations) at the level of the posterior columns cephalad to the primary injury site on T2-weighted and proton density-weighted imaging at 10 week to 12 month intervals postinjury. In these six patients the posterior column was involved at the primary injury site. CONCLUSION: The abnormal intensity cephalad to the injury site is thought to represent wallerian degeneration, which should be considered in the differential diagnoses of spinal intramedullary lesions.

Significance of Gd-DTPA-enhanced magnetic resonance imaging for lumbar disc herniation: the relationship between nerve root enhancement and clinical manifestations.

Gd-DTPA-enhanced magnetic resonance (MR) imaging can depict not only the morphology but also the pathological changes of a nerve root compressed by herniated disc. Enhanced MR imaging was performed on 115 patients treated surgically for lumbar disc herniation. Nerve root enhancement was seen in 39.1% of the patients preoperatively and in 58.7% postoperatively. Preoperative root enhancement reflects the radicular pain intensity rather than the degree of neurological deficits, whereas postoperative enhancement did not correlate with the radicular symptoms. Nerve root enhancement represents an intraneural edema in the affected nerve root. Enhanced MR imaging is a potential method for the identification of an affected nerve root in patients with a discrepancy between the level of disc herniation and neurological manifestations.

Monitoring the evolution of intramedullary lesions in cervical spinal cord injury. Qualitative and quantitative analysis with sequential MR imaging.

The evolution of intramedullary lesions following an acute spinal cord injury was monitored with sequential magnetic resonance (MR) imaging. Seven patients who had sustained cervical spinal cord injuries were followed up from the acute to the chronic phase of the cord injury. MR images were evaluated not only qualitatively but also quantitatively. All intramedullary lesions were quantitatively analysed by T2 values. In the qualitative analysis, the regions with hyperintensity on T2-weighted images and isointensity on T1-weighted images were consistent with the region of simple oedema or gliosis. The former gradually disappeared after the acute phase, whereas the latter remained until the chronic phase. The regions with hyperintensity on T2-weighted images and hypointensity on T1-weighted images may represent cysts filled with necrotic tissue or clear fluid, or necrosis. The evolution of these lesions was also able to be monitored quantitatively by T2 values.