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Biomedical subjects

Yukihiro Hama

Publications and source records attributed to Yukihiro Hama.

At least 19 recordsLinked to original sources
PubMed2006

Successful coil embolization of a ruptured hepatic aneurysm in a patient with polyarteritis nodosa accompanied by angioimmunoblastic T cell lymphoma.

Polyarteritis nodosa (PN) occasionally develops in association with malignant disorders. A 71-year-old man suddenly suffered from bleeding due to the rupture of a hepatic artery aneurysm. The ruptured lesion was embolized endovascularly by coiling, and the bleeding was stopped. A biopsy of the right inguinal lymph node demonstrated angioimmunoblastic T cell lymphoma (AITL). He received immunosuppressive treatment with transient response, although he relapsed 4 months later. To our knowledge, this is the first case of which PN was associated with AITL.

Aged↗
PubMed2006

Simultaneous two-color spectral fluorescence lymphangiography with near infrared quantum dots to map two lymphatic flows from the breast and the upper extremity.

Due to their small size and poor access, the lymphatic function has been difficult to study in vivo. Especially difficult is the mapping of lymphatic drainage from two basins into the same node. Quantum dots can be used to perform multicolor images with high fluorescent intensity and are of a nano-size size suitable for lymphatic imaging via direct interstitial injection. Here we show simultaneous two-color in vivo wavelength-resolved spectral fluorescence lymphangiography using two near infrared quantum dots with different emission spectra, which allow non-invasive and simultaneous visualization of two separate lymphatic flows draining the breast and the upper extremity and variations in the drainage patterns and the water sheds within the axillary node. Two-color spectral fluorescence lymphangiography can provide insight into mechanisms of drainage from different lymphatic basins that may lead to sentinel lymph nodes detection of the breast cancer as well as prevention of complications such as lymphedema of the arm.

Animals↗
PubMed2006

Targeted optical imaging of cancer cells using lectin-binding BODIPY conjugated avidin.

Lectins (asialo-receptor family) are expressed on a number of tumors that develop peritoneal metastases. To demonstrate that fluorescence imaging based on lectin binding is applicable for a variety of tumors, we conjugated BODIPY to avidin (avidin-BODIPY), and studied the efficacy of tumor targeting in 9 cancer cell lines in vitro and an ovarian cancer cell line in vivo using a murine peritoneal cancer model. All 9 cell lines showed specific intracellular accumulation with avidin-BODIPY on fluorescence microscopy and flow cytometry. In vivo spectral molecular imaging clearly visualized the peritoneal tumor foci with avidin-BODIPY, whereas, deglycosylated avidin-BODIPY (neutravidin-BODIPY) showed only minimal fluorescence from the tumor foci and was accompanied by higher background signals. These results suggest the lectin-targeted molecular imaging technique using a targeted green fluorescence probe is potentially useful in a wide variety of cancers with a proclivity for dissemination in the peritoneal space.

Animals↗
PubMed2006

Impact of written information consent on the number of intravenous contrast--enhanced CT and MR studies.

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the impact of written informed consent on the number of intravenous contrast-enhanced CT and MR imaging studies. MATERIALS AND METHODS: On December 2002, the Conference of Physicians and Medical Directors in our institution decided that all referring physicians must obtain written informed consent in each case before intravenous injection of contrast material for CT and MR imaging studies. The numbers and proportions of contrast-enhanced CT and MR imaging studies before introduction of the written informed consent requirement (January 2002-December 2002) were compared with those after (January 2003-December 2003). RESULTS: The number of contrast-enhanced CT studies decreased from 5930 (50.6% of all CT studies) to 5539 (49.0% of all CT studies) (odd ratio [OR]: 0.94, 95% confidence interval [CI]: 0.89-0.99). The number of contrast-enhanced MR studies also decreased from 1895 (46.5% of all MR studies) to 1712 (43.4% of all MR studies) (OR: 0.88, 95% CI: 0.81-0.96). CONCLUSION: Findings suggest that the written informed consent requirement reduces the number of intravenous contrast-enhanced CT and MR imaging studies.

Contrast Media↗
PubMed2006

In vivo spectral fluorescence imaging of submillimeter peritoneal cancer implants using a lectin-targeted optical agent.

Intraperitoneal metastases commonly recur after surgery because small tumor foci escape detection within the complex anatomy of the peritoneal cavity and mesentery. Accurate localization of peritoneal implants during surgery could improve the resection of ovarian cancer and other malignancies, but few practical techniques to enhance detectability are currently available. Here, we describe a targeted molecular imaging method that employs fluorescently labeled avidin to detect submillimeter peritoneal implants of ovarian cancer in mice. After binding to surface lectins on the tumor, fluorescein-conjugated avidin enabled the spectral fluorescence imaging of disseminated peritoneal implants. High spatial resolution and high tumor-to-background ratio allowed the visualization of implants as small as 0.3 mm (with 100% sensitivity and specificity; n = 150) and the identification of even smaller lesions ex vivo. These results suggest that targeted molecular imaging with a fluorescence-labeled lectin-ligand system is a promising technique for the detection of disseminated submillimeter foci of cancer.

Animals↗
PubMed2006

Mucinous adenocarcinoma arising from fistula in ano: MRI findings.

OBJECTIVE: The purpose of this study was to describe MRI findings in 11 patients with mucinous adenocarcinomas arising from fistula in ano. CONCLUSION: More than half of patients had a mass filled with markedly hyperintense content on T2-weighted fast spin-echo images, enhancing solid components within the mass, mesh-like internal enhancement, fluid collections without a thick fibrous capsule, contrast enhancement of peritumoral areas, and a fistula between the mass and the anus. Regional areas of lymph node enlargement were considered indirect findings of locally advanced mucinous adenocarcinoma. These MRI findings may help diagnose mucinous adenocarcinomas arising from fistula in ano.

Adenocarcinoma, Mucinous↗
PubMed2006

Retaining self-determined goals and the impact on examination scores.

OBJECTIVE: To determine how many students retained their own goals during a 6-month radiology course and to evaluate the impact on the final examination scores. METHODS: At the beginning of the radiology course in 2003, all first-year military nursing students (N = 60) were asked to list their self-determined goals for learning radiology. After the 6-month course, they were asked to restate their initial self-determined goals, without previous notice. The replies were classified into three groups, as follows: group 1, those who did not restate their own goals accurately; group 2, those who restated their own goals accurately; group 3, those who stated, "I don't remember." The mean examination scores for the groups were compared by using Student's t test. RESULTS: The mean score (mean +/- SD, 69.6 +/- 6.9) for students in group 3 was significantly higher than that (mean +/- SD, 61.8 +/- 5.8) for students in group 1 (p = 0.003). The mean score (mean +/- SD, 64.7 +/- 6.9) for group 2 was higher than that for group 1, but the difference was not statistically significant (p = 0.109). CONCLUSIONS: Retaining self-determined goals has clear advantages in a military nursing school. However, those who are honest and report forgetting their self-determined goals do not always achieve poor results on the examination.

Educational Measurement↗
PubMed2005

Small left atrium: an adjunctive sign of hemodynamically compromised massive pulmonary embolism.

Pulmonary embolism (PE) is a common disease with a high mortality rate due to right ventricular dysfunction and underfilling of the left ventricle. We present a case of a 33-year-old man with hemodynamically compromised massive PE. His left atrium was collapsed with marked dilatation of the right atrium and ventricle on multi-detector-row CT scans. The patient was treated with an intracatheter injection of a mutant tissue-type plasminogen activator and subsequently showed clinical and radiological improvements. The small left atrial size in combination with a right ventricular pressure overload was considered to be an adjunctive sign of hemodynamically compromised massive PE.

Adult↗
PubMed2005

Foot pedal-activated injector for contrast-enhanced sonography.

We assessed the feasibility and convenience of an injector that is electrically activated by a foot pedal for contrast-enhanced sonography. Thirty-seven patients with liver lesions underwent contrast-enhanced sonography using an injector that is activated by a foot pedal. The contrast agent was injected by pressing the foot pedal. All the studies were successfully performed without complications. The device enables the sonologist to keep the probe stationary during the injection and avoids the need for additional personnel. Pedal activated injection is a safe, useful, and convenient method of contrast-enhanced sonography.

Contrast Media↗
PubMed2005

Internal mammary artery injury following subclavian vein catheterization.

Inappropriate puncture of the internal mammary artery caused by subclavian vein puncture is a rare but potentially lethal complication. We report a case of 45-year-old woman with internal mammary artery injury following subclavian vein catheterization successfully treated by transcatheter arterial embolization using coils.

Angiography↗
PubMed2005

Endovascular stent placement for malignant stenosis and occlusion of the bilateral iliac veins and inferior vena cava after failure of radiation therapy.

A 70-year-old woman with advanced ureteral carcinoma was referred due to stenosis and occlusion of the bilateral iliac veins and inferior vena cava after failure of radiation therapy. We successfully placed endovascular stents in the bilateral iliac veins and the inferior vena cava. The stents remain patent after five months of follow-up without requiring secondary intervention. As far as we know, this is the first report of radioresistant malignant stenosis of the bilateral iliac veins and the inferior vena cava that was successfully treated with stent placement.

Journal Article↗
PubMed2005

Teaching radiology to military nursing students.

OBJECTIVES: To assess the students' perceptions and evaluations of radiology lectures and to determine the factors correlating with performance on examinations. METHODS: Sixty-three nursing students were asked to submit their opinions regarding the lecture at the end of each lecture, and they were asked to evaluate the lectures as a whole at the end of the course. Relationships between each of the survey items (student curiosity, overall understanding, usefulness of the lecture, difficulty level, incentive to study, and total number of opinions regarding the lecture) and the final examination score were examined with Spearman correlation analysis. RESULTS: Statistically significant positive correlations were found between student curiosity and the final examination score (n = 62, rs = 0.281, p < 0.028) and between the total number of opinions and the final examination score (n = 63, rs = 0.273, p < 0.032). However, the other variables did not reach statistical significance. CONCLUSIONS: Our results suggest that lectures enhancing student curiosity and eliciting feedback from students may be related to high performance on examinations.

Educational Measurement↗
PubMed2004

Pleomorphic sarcoma of the adult urinary bladder: sonographic findings.

Sarcomas with muscular differentiation (eg, rhabdomyosarcoma, leiomyosarcoma, pleomorphic sarcoma) are uncommon in the adult urinary bladder. We report the sonographic findings in a case of pleomorphic sarcoma with muscular differentiation arising from the bladder dome that mimicked urachal carcinoma; findings of correlative imaging are also discussed.

Abdominal Neoplasms↗
PubMed2003

J-tipped guidewire as a target for puncture of the subclavian artery in the placement of a reservoir port and catheter system.

The aim of this study was to verify the feasibility of using a J-tipped guidewire as a target for puncture of the subclavian artery in the placement of a reservoir port and catheter system (RPCS). Twenty-five patients with various hepatic malignancies underwent percutaneous implantation of an RPCS through the left subclavian artery for regional chemotherapy. To successfully puncture the left subclavian artery, a J-tipped guidewire was used as a target with fluoroscopic guidance. Technical success and complication rates, and numbers of puncture failures, were retrospectively analyzed. Implantation of the RPCS was successful in all patients. Eight (32%) patients had minor complications and no patient had major complications. The number of puncture failures per patient was 0 to 1 (mean=0.32). The J-tipped guidewire is a safe and appropriate target for puncture of the subclavian artery in the placement of an RPCS.

Adult↗