Biomedical subjects

Hiroto Hatabu

Publications and source records attributed to Hiroto Hatabu.

At least 37 records · Page 2Linked to original sources

PubMed2005

Multislice CT evaluation of airway stents.

Tracheobronchial stents are playing an increasing role in the palliative treatment of large airway obstruction due to a variety of conditions, including extrinsic compression, intraluminal disease, and malacia. Computed tomography (CT) plays an important role in aiding planning of stent placement and in detecting various stent complications. In this pictorial essay, we illustrate and review the role of multislice CT in the pre- and post-stent placement settings. A special emphasis is placed upon the characteristic CT appearance of specific stent complications and upon the role of CT multiplanar reformations and 3-dimensional (3-d) reconstruction techniques.

Airway Obstruction↗

PubMed2005

Volumetric expiratory HRCT imaging with MSCT.

Expiratory HRCT is a powerful adjunct to inspiratory HRCT for detecting various small airway diseases. Current standard expiratory HRCT protocol consists of a limited number of non-contiguous scans at selected levels. We have developed a new volumetric expiratory HRCT protocol that allows volumetric data acquisition of lungs both at end-inspiration and end-expiration. By reducing the x-ray tube current, the radiation dose of this new protocol is equivalent to the standard expiratory HRCT protocol at our institution. This volumetric expiratory HRCT has been applied in patients with diffuse lung disease with small airway abnormalities. In this review, we describe: (1) technical considerations of VEHRCT including dose reduction, (2) the advantages of contiguous scans and multiplanar reformations, (3) clinical application of volumetric expiratory HRCT in various diffuse lung diseases, and (4) future directions including computational qualitative assessment of lung biomechanics.

Exhalation↗

PubMed2005

High-resolution computed tomography findings of P. westermani.

Paragonimiasis westermani, or Oriental lung fluke, is a common parasitic zoonosis, which is acquired from eating the flesh of wild boar or freshwater crabs. After being ingested by humans, the larvae of P. westermani migrate across small intestinal mucosa into the intra-abdominal space, and then finally into to the pleural space and lung parenchyma. High-resolution CT findings of P. westermani consist of worm cysts, migration track, peripheral density, bronchial wall thickening, and centrilobular nodules, which prompt serological tests and detection of eggs in sputum or BAL fluid for definitive diagnosis.

Adult↗

PubMed2004

Single-shot half-Fourier RARE sequence with ultra-short inter-echo spacing for lung imaging.

PURPOSE: To improve the image quality of pulmonary magnetic resonance (MR) imaging using an ultra-short inter-echo spacing half-Fourier single shot rapid acquisition with relaxation enhancement (USHA-RARE) sequence. MATERIALS AND METHODS: Pulmonary MR images were acquired by USHA-RARE sequence with various inter-echo spacings. The sequence parameters were as follows: repetition time (TR)/effective TE: infinite/39-41 msec; section thickness: 10 mm; acquisition matrix: 128 x 128; field of view: 450 x 450 mm. Inter-echo spacing varied (2.5 msec, 3.0 msec, 3.5 msec, 4.0 msec, 4.5 msec, 5.0 msec), and the respective phase-encoding steps were 80, 77, 75, 74, 73, and 72. Signal-to-noise ratios (SNRs), the signal ratios between lung and fat (lung-to-fat ratio: LFRs), and the signal ratios between the lung and the serratus anterior muscle (lung-to-muscle ratio: LMRs) of each inter-echo spacing were calculated, and statistically evaluated. RESULTS: The SNRs at inter-echo spacings of < or = 3.0 msec were significantly higher than those > or = 4.0 msec (P < 0.05). The LFRs and LMRs at inter-echo spacing < or = 3.0 msec were significantly higher than those > or = 4.0 msec (P < 0.05). CONCLUSION: USHA-RARE sequence does improve signal intensity from the lung.

Adult↗

PubMed2004

Quantitative assessment of regional pulmonary perfusion in the entire lung using three-dimensional ultrafast dynamic contrast-enhanced magnetic resonance imaging: Preliminary experience in 40 subjects.

PURPOSE: To assess regional differences in quantitative pulmonary perfusion parameters, i.e., pulmonary blood flow (PBF), mean transit time (MTT), and pulmonary blood volume (PBV) in the entire lung on a pixel-by-pixel basis in normal volunteers and pulmonary hypertension patients. MATERIALS AND METHODS: Three-dimensional ultrafast dynamic contrast-enhanced MR imaging was performed in 15 normal volunteers and 25 patients with pulmonary hypertension. From the signal intensity-time course curves, PBF, MTT and PBV maps were generated using deconvolution analysis, indicator dilution theories, and the central volume principle, on a pixel-by-pixel basis. From pulmonary perfusion parameter maps of normal volunteers and pulmonary hypertension patients, regional PBF, MTT, and PBV were statistically evaluated. RESULTS: Regional PBF, MTT, and PBV showed significant differences in the gravitational and isogravitational directions (P < 0.05). The quantitative pulmonary perfusion parameter maps demonstrated significant differences between normal volunteers and pulmonary hypertension patients (P < 0.05). CONCLUSION: Three-dimensional ultrafast dynamic contrast-enhanced MR imaging is feasible for the assessment of regional quantitative pulmonary perfusion parameters in the entire lung on a pixel-by-pixel basis in normal volunteers and pulmonary hypertension patients.

Adult↗

PubMed2004

Use of personal digital assistants in diagnostic radiology resident education.

RATIONALE AND OBJECTIVES: Personal digital assistants (PDAs) are gaining widespread use in the medical community. We introduced a PDA-based mobile system that provides departmental and educational information with a seamless connection to the intranet. The objective of this study is to determine the impact a PDA has on educational resources (learning or data reference) brought to work and used at home by a radiology resident based on user surveys. MATERIALS AND METHODS: Survey was performed on 32 radiology residents in our department before and 6 months after the release of the PDA-based system. We assessed the changes in (1) sources of learning at home and at work, and in (2) data reference. The second survey also evaluated the usefulness of each component of the system. RESULTS: After the release of the PDA-based mobile system, the use of "digital books and references" as data references and educational resources that were brought to work every day significantly increased (P = .016, P < .0001, respectively). "Traditional books and references" remained the "most useful source in learning radiology"; however, "digital books and references" increased as the residents' first choice from 0% to 16% within 6 months of introducing the package (P = .125). CONCLUSION: The introduction of a PDA-based system consisting of educational and departmental information had a statistically significant impact in increasing the use of digitized information in radiology resident education.

Computers, Handheld↗

PubMed2004

Comprehensive innovative solution for resident education using the Intranet Journal of Chest Radiology.

RATIONALE AND OBJECTIVES: Because of the rapid increase in clinical workload in academic radiology departments, time for teaching rotating residents is getting more and more limited. As a solution to this problem, we introduced the Intranet Journal of Chest Radiology as a comprehensive innovative tool for assisting resident education. MATERIALS AND METHODS: The Intranet Journal of Chest Radiology is constructed using Microsoft FrontPage version 2002 (Microsoft Corp, Redmond, WA) and is hosted in our departmental web server (Beth Israel Deaconess Medical Center, Boston, MA). The home page of the intranet journal provides access to the main features, "Cases of the Month," "Teaching File," "Selected Articles for Residents," "Lecture Series," and "Current Publications." These features provide quick access to the selected radiology articles, the interesting chest cases, and the lecture series and current publication from the chest section. RESULTS: Our intranet journal has been well utilized for 6 months after its introduction. It enhances residents' interest and motivation to work on case collections, to search and read articles, and to generate interest in research. Frequent updating is necessary for the journal to be kept current, relevant, and well-utilized. CONCLUSION: The intranet journal serves as a comprehensive innovative solution for resident education, providing basic educational resources and opportunities of interactive participation by residents.

Computer Communication Networks↗

PubMed2004

Sagittal reformations of volumetric inspiratory and expiratory high-resolution CT of the lung.

RATIONALE AND OBJECTIVES: The purpose of this study is to determine whether sagittal reformations of volumetric high-resolution computed tomography (CT) provide additional information in evaluating lung abnormalities compared to axial high-resolution CT images. MATERIALS AND METHODS: Twenty-two consecutive patients who underwent combined inspiratory and expiratory volumetric high-resolution CT from May to July 2003 were studied. Using end-inspiratory and end-expiratory sagittal reformatted images, respiratory motion artifacts were evaluated at upper, middle, and lower lung areas bilaterally. Diaphragmatic motion artifacts were evaluated bilaterally. The detection of major and minor fissures was assessed. Additional findings on sagittal reformations were graded using a three-point scale: grade 1 = no additional findings; grade 2 = additional findings of no diagnostic significance; grade 3 = additional findings of diagnostic significance. RESULTS: Respiratory motion artifacts were either imperceptible or present but not diagnostically limiting except for one case, in which diagnostically limiting image degradation was noted in the bilateral lower lung areas. Diaphragmatic motion artifacts were frequently present: 95% (21/22) at end-inspiration, and 86% (19/22) at end-expiration; however, diagnostically limiting artifacts were observed in only two cases. The grading of additional findings on sagittal reformatted images was statistically significant (grade 1, n = 13; grade 2, n = 7; grade 3, n = 2; median, 1; P = .004) compared to axial images. Additional findings included relationship between mass/nodules and fissure/pleura/pericardium (grade 2, n = 4; grade 3, n = 2), distribution of interstitial abnormalities of the lung (grade 2, n = 2), and diaphragmatic eventration (grade 2, n = 1). CONCLUSION: Sagittal reformatted images of volumetric high-resolution CT provided additional information compared to volumetric axial images alone with statistical significance.

Adult↗

PubMed2004

Volumetric expiratory high-resolution CT of the lung.

We developed a volumetric expiratory high-resolution CT (HRCT) protocol that provides combined inspiratory and expiratory volumetric imaging of the lung without increasing radiation exposure, and conducted a preliminary feasibility assessment of this protocol to evaluate diffuse lung disease with small airway abnormalities. The volumetric expiratory high-resolution CT increased the detectability of the conducting airway to the areas of air trapping (P<0.0001), and added significant information about extent and distribution of air trapping (P<0.0001).

Adult↗

PubMed2004

Dynamic MR imaging: value of differentiating subtypes of peripheral small adenocarcinoma of the lung.

PURPOSE: To determine the utility of dynamic magnetic resonance imaging (MRI) in the differential subtyping of small adenocarcinomas of the lung. MATERIALS AND METHODS: Twenty-nine pathologically diagnosed peripheral adenocarcinomas (less than 20 mm in diameter) underwent dynamic contrast-enhanced MRI. Maximum relative enhancement ratio, slope of enhancement, and corrected start time of enhancement were calculated from signal intensity-time curve of pulmonary lesion for each subject, and were statistically compared among bronchioloalveolar carcinoma (BAC) group (7 cases), mixed BAC group (10 cases), and adenocarcinoma group (12 cases). RESULTS: Maximum relative enhancement ratio (P<0.001) and slope of enhancement (P<0.001) of BAC group were significantly higher than those of mixed BAC and adenocarcinoma groups. Start times of BAC group were significantly earlier than those of mixed BAC (P=0.0001) and adenocarcinoma groups (P<0.0001). Adapting the thresholds values of MR indexes from the positive tests, sensitivity, specificity, positive predictive value, negative predictive value and accuracy for differentiating BAC from other subtypes were 85.7, 100.0, 100.0, 95.7, and 96.6%, respectively. CONCLUSIONS: Dynamic MRI is useful for differentiating subtypes of small peripheral adenocarcinoma.

Adenocarcinoma↗

PubMed2004

Centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo sequence: improvement of the image quality of oxygen-enhanced MRI.

PURPOSE: The purpose of the study presented here was to determine the improvement in image quality of oxygen-enhanced magnetic resonance (MR) subtraction imaging obtained with a centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo (c-IR-HASTE) sequence compared with that obtained with a conventional sequentially reordered inversion recovery single-shot HASTE (s-IR-HASTE) sequence for pulmonary imaging. MATERIALS AND METHODS: Oxygen-enhanced MR imaging using a 1.5 T whole body scanner was performed on 12 healthy, non-smoking volunteers. Oxygen-enhanced MR images were obtained with the coronal two-dimensional (2D) c-IR-HASTE sequence and 2D s-IR-HASTE sequence combined with respiratory triggering. For a 256x256 matrix, 132 phase-encoding steps were acquired including four steps for phase correction. Inter-echo spacing for each sequence was 4.0 ms. The effective echo time (TE) for c-IR-HASTE was 4.0 ms, and 16 ms for s-IR-HASTE. The inversion time (TI) was 900 ms. To determine the improvement in oxygen-enhanced MR subtraction imaging by c-IR-HASTE, CNRs of subtraction image, overall image quality, and image degradation of the c-IR-HASTE and s-IR-HASTE techniques were statistically compared. RESULTS: CNR, overall image quality, and image degradation of c-IR-HASTE images showed significant improvement compared to those s-IR-HASTE images (P<0.05). CONCLUSION: Centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo (c-IR-HASTE) sequence enhanced the signal from the lung and improved the image quality of oxygen-enhanced MR subtraction imaging.

Adult↗

PubMed2004

Transthoracic CT-guided biopsy with multiplanar reconstruction image improves diagnostic accuracy of solitary pulmonary nodules.

OBJECTIVE: To evaluate the utility of multiplanar reconstruction (MPR) image for CT-guided biopsy and determine factors of influencing diagnostic accuracy and the pneumothorax rate. MATERIALS AND METHODS: 390 patients with 396 pulmonary nodules underwent transthoracic CT-guided aspiration biopsy (TNAB) and transthoracic CT-guided cutting needle core biopsy (TCNB) as follows: 250 solitary pulmonary nodules (SPNs) underwent conventional CT-guided biopsy (conventional method), 81 underwent CT-fluoroscopic biopsy (CT-fluoroscopic method) and 65 underwent conventional CT-guided biopsy in combination with MPR image (MPR method). Success rate, overall diagnostic accuracy, pneumothorax rate and total procedure time were compared in each method. Factors affecting diagnostic accuracy and pneumothorax rate of CT-guided biopsy were statistically evaluated. RESULTS: Success rates (TNAB: 100.0%, TCNB: 100.0%) and overall diagnostic accuracies (TNAB: 96.9%, TCNB: 97.0%) of MPR were significantly higher than those using the conventional method (TNAB: 87.6 and 82.4%, TCNB: 86.3 and 81.3%) (P < 0.05). Diagnostic accuracy were influenced by biopsy method, lesion size, and needle path length (P < 0.05). Pneumothorax rate was influenced by pathological diagnostic method, lesion size, number of punctures and FEV1.0% (P < 0.05). CONCLUSION: The use of MPR for CT-guided lung biopsy is useful for improving diagnostic accuracy with no significant increase in pneumothorax rate or total procedure time.

Adolescent↗

PubMed2004

Mixture distribution analysis of a computer assisted diagnostic method for the evaluation of pulmonary nodules on computed tomography scan.

RATIONALE AND OBJECTIVES: To compare the effectiveness of a new computational scheme for pulmonary nodule detection in computed tomography images against human observers. MATERIALS AND METHODS: The study involved evaluation of 81 potential nodules by four radiologists. Each radiologist separately evaluated the potential nodules and provided a confidence level for the presence of pulmonary nodules. Their performance was compared with that of the new computational scheme by mixture distribution analysis. RESULTS: Mixture distribution analysis of the results of the four radiologists demonstrated a relative proportion agreement of 0.84. The kappa statistic was used to compare the agreement of the computational scheme with the results of the four radiologists. A kappa value of .65 (se = .11) was shown to be significantly different from chance (P = .99). CONCLUSION: The new computational scheme correlates well with the radiologists' subjective rankings of pulmonary nodules on computed tomography scans and may prove a useful tool in the evaluation of algorithms for the screening and diagnosis of lung cancer.

Humans↗

PubMed2004

Architecture of the lung: morphology and function.

The architecture of the lung is discussed with special focus on lung parenchyma. The lung parenchyma is mainly comprised of numerous air-containing passages and intervening fine structures, corresponding to alveolar ductal lumens and alveoli, as well as alveolar septa and small pulmonary vessels occupying 10% of total parenchymal volume. The shapes and relative arrangements of alveolar ducts and alveoli are discussed in detail, which is followed by a brief description of bronchial circulation and pulmonary lymphatics.

Bronchi↗

PubMed2004

MR evaluation of pulmonary blood flow.

Pulmonary blood flow is one of the primary determinants of gas exchange. While a number of methods can be used to evaluation pulmonary perfusion, these have substantial limitations. In this paper, we discuss the use of magnetic resonance imaging techniques for the evaluation of pulmonary blood flow. While these methods are not commonly used at present, they have the potential to contribute greatly to the evaluation of suspected pulmonary vascular disease.

Animals↗

PubMed2004

Metastases in mediastinal and hilar lymph nodes in patients with non-small cell lung cancer: quantitative and qualitative assessment with STIR turbo spin-echo MR imaging.

PURPOSE: To evaluate short inversion time inversion-recovery (STIR) turbo spin-echo (TSE) magnetic resonance (MR) imaging for detection of metastases in lymph nodes by using quantitative and qualitative analyses. MATERIALS AND METHODS: One hundred ten patients (68 men and 42 women) with non-small cell lung cancer who ranged in age from 36 to 82 years (mean age, 64 years) were examined with respiratory-triggered STIR TSE MR imaging. Ratios of signal intensity in a lymph node to that in a 0.9% saline phantom (lymph node-saline ratios [LSRs]) for all lymph nodes were classified into three groups according to nodal short-axis diameter. LSRs of each group were compared by using pathologic diagnosis as the standard of reference. For quantitative analysis, the LSR threshold value for a positive test was determined on a per-node basis and tested for ability to enable a correct diagnosis on a per-patient basis. For qualitative analysis, signal intensities of lymph nodes were assessed by using a five-point visual scoring system. Results of quantitative and qualitative analyses were compared on a per-patient basis with McNemar testing. RESULTS: In 110 patients, 92 of 802 lymph nodes were pathologically diagnosed as containing metastases, while 710 lymph nodes did not contain metastases. Mean LSR in the lymph node group with metastasis was higher than that in the group without metastasis (P <.05). When an LSR of 0.6 was used as the positive-test threshold at quantitative analysis, sensitivity was 93% (37 of 40 patients) and specificity was 87% (61 of 70 patients) on a per-patient basis. With a score of 4 as the positive-test threshold at qualitative analysis, sensitivity was 88% (35 of 40 patients) and specificity was 86% (60 of 70 patients) on a per-patient basis. There was no significant difference (P >.05) between results of quantitative and those of qualitative analysis. CONCLUSION: Quantitative and qualitative analyses of STIR TSE MR images enable differentiation of lymph nodes with metastasis from those without. Qualitative analysis can substitute for quantitative analysis of STIR TSE MR imaging data.

Adult↗

PubMed2004

Bronchial artery dilatation on MDCT scans of patients with acute pulmonary embolism: comparison with chronic or recurrent pulmonary embolism.

OBJECTIVE: The purpose of our study was to compare the bronchial arteries of patients with acute pulmonary embolism with those of patients with chronic or recurrent pulmonary embolism. MATERIALS AND METHODS: Twenty-seven patients with acute pulmonary embolism and 14 patients with chronic or recurrent pulmonary embolism were retrospectively identified from 700 consecutive patients with suspected pulmonary embolism. The case data for the patients were assessed by two thoracic radiologists whose final judgments were reached by consensus. On the MDCT pulmonary angiograms obtained in these patients, the bronchial arteries were assessed by finding enhancing, small, round or curvilinear structures within the mediastinum and tracing their paths along the bilateral main bronchi. Bronchial arteries with a diameter greater than 1.5 mm were considered to be dilated. RESULTS: The diameters of the bronchial arteries in the group with chronic or recurrent pulmonary embolism were significantly larger than diameters of the bronchial arteries in the group with acute pulmonary embolism (p = 0.0002). Dilatation of bronchial arteries was observed in two of the 27 patients with acute pulmonary embolism and in seven of 14 patients with chronic or recurrent pulmonary embolism. This difference was statistically significant (p = 0.004). No dilated bronchial arteries were seen in patients who had acute pulmonary embolism but had no a history of deep venous thrombosis. CONCLUSION: Acute pulmonary embolism did not appear to cause dilatation of bronchial arteries, whereas chronic or recurrent pulmonary embolism was frequently associated with dilated bronchial arteries. In patients in whom the distinction between acute and chronic or recurrent pulmonary embolism on MDCT pulmonary angiography is clinically unclear and in whom the bronchial arteries are dilated, a diagnosis of chronic or recurrent pulmonary embolism should be favored.

Acute Disease↗

PubMed2004

Dynamic perfusion MRI versus perfusion scintigraphy: prediction of postoperative lung function in patients with lung cancer.

OBJECTIVE: The purpose of this study was to determine the capability of dynamic perfusion MRI as an alternative to pulmonary perfusion scintigraphy for prediction of postoperative lung function in patients with lung cancer. SUBJECTS AND METHODS. Sixty patients with lung cancer (35 men, 25 women) underwent dynamic perfusion MRI, perfusion scintigraphy, and preoperative and postoperative pulmonary function tests (forced expiratory volume in 1 sec [FEV(1)]). Perfusion MRIs were obtained with a 3D turbo field-echo sequence (TR/TE, 2.7/0.6; flip angle, 40 degrees; matrix, 128 x 96) using a 1.5-T scanner. Regional blood flow was calculated from the signal intensity-time curves after bolus injection of contrast medium on MRI (Q(MRI)) and uptake ratios of radioisotope on perfusion scintigraphy (Q(PS)). Postoperative lung functions predicted by MRI (FEV(1,MRI)) and perfusion scintigraphy (FEV(1,PS)) were calculated from preoperative FEV(1) and regional Qs. To determine the capability of MRI as an alternative to scintigraphy, we evaluated correlations and the limits of agreement between predicted FEV(1,MRI) and postoperative FEV(1) and between predicted FEV(1,PS) and postoperative FEV(1). RESULTS: The correlation coefficient of postoperative FEV(1) with FEV(1,MRI) (r = 0.93, p < 0.0001) was better than that with FEV(1,PS) (r = 0.89, p < 0.0001). The limits of agreement between postoperative FEV(1) and predicted FEV(1,MRI) (0.9% +/- 10.4%) were smaller than those between postoperative FEV(1) and predicted FEV(1,PS) (2.1% +/- 13.2%). CONCLUSION: Dynamic perfusion MRI is a feasible alternative to pulmonary perfusion scintigraphy for predicting postoperative lung function in patients with lung cancer.

Adult↗