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Biomedical subjects

K Togashi

Publications and source records attributed to K Togashi.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

Uterine contractions: possible diagnostic pitfall at MR imaging.

A total of 206 nongravid patients with various gynecologic problems underwent pelvic magnetic resonance (MR) examinations that included both sagittal T2-weighted and contrast agent-enhanced T1-weighted images. MR images were retrospectively reviewed to identify changes in endometrial configuration on serial images obtained during the same MR examination. In 20 MR examinations (all in women of reproductive age), endometrial distortion due to myometrial bulging was noted on T2-weighted or contrast-enhanced T1-weighted images. It was absent on other MR images obtained at different times. Myometrial bulging exhibited low signal intensity in 18 examinations. The finding resembled adenomyosis or leiomyoma on T2-weighted or contrast-enhanced T1-weighted images. These results evidence the presence of transient myometrial bulging and transient low-intensity myometrium in the nongravid uterus. This phenomenon is thought to represent uterine contraction. Clinicians should be aware of the potential presence of transient low-signal-intensity myometrial bulging that could present diagnostic problems in the normal uterus.

Adolescent↗
PubMedDate not supplied

Cervical cancer.

The stage estimated by clinical FIGO staging is the main determinant in guiding the treatment decisions. However, clinical FIGO staging does have inherent inaccuracies, because it does not include significant prognostic factors. Presently, MRI is not officially incorporated in the staging workup system; however, it is widely accepted as the most reliable imaging modality in evaluating cervical cancer and in treatment planning. MRI offers direct tumor visualization, accurate assessment of the depth of stromal invasion and tumor volume, lymph node evaluation, and reliable staging accuracy. Published reports show the superiority of MRI over clinical staging, and several recent works on dynamic MRI suggest further improvement of MRI in evaluating cervical cancer.

Contrast Media↗
PubMedDate not supplied

Metastatic lymph nodes in urogenital cancers: contribution of imaging findings.

The presence of nodal metastasis in patients with urogenital malignancies is an important factor for prognosis, and radiologic identification of enlarged nodes greatly affects treatment choices. Radiologic evaluation for nodal metastases is usually performed with computed tomography, but magnetic resonance imaging is also useful in evaluating primary and nodal metastases in pelvic tumors. On these cross-sectional modalities, nodal metastases are usually suspected according to location and size criteria. Although there has been no general consensus on the criteria, a short axis diameter of 8 to 10 mm is generally applied. However, radiologic evaluation does not always provide sufficient accuracy for nodal staging because of an inability to diagnose smaller metastatic lymph nodes. The clinical significance of a radiologic recognition of enlarged nodes also differs by cancer type in relation to differences in staging systems and treatment. The presence of regional lymphadenopathy in patients with renal cell carcinoma often alters surgical methods, whereas the presence of regional lymphadenopathy is an indication of systemic chemotherapy in patients with cancers of the urinary tract, prostate, and testicles. In this report, preferential sites and staging of nodal metastasis and contributions of radiologic imaging are reviewed for each urogenital cancer.

Humans↗
PubMedDate not supplied

Solid mature teratoma of the ovary: appearances at MR imaging.

Magnetic resonance imaging (MRI) appearances of a case with rare solid mature teratoma of the ovary is presented. The lesion was almost entirely solid with small cystic component. The solid tissue, consisting of bronchial cartilage, smooth muscle, glands, and epithelium, exhibited hypointense signal on T1-weighted image, relatively hyperintense signal on T2-weighted image, and reticular pattern of enhancement on the postcontrast scan. The presence of fatty tissue mixed with hair bundle, which did not exhibit a signal intensity of fatty tissue, was clearly indicated by chemical shift artifact within the cystic component.

Adult↗
PubMedDate not supplied

Comparison of the macromolecular MR contrast agents with ethylenediamine-core versus ammonia-core generation-6 polyamidoamine dendrimer.

Two novel macromolecular MRI contrast agents based upon generation-6 polyamidoamine dendrimers (G6) of presumed similar molecular size, but of different molecular weight, were compared in terms of their blood retention, tissue distribution, and renal excretion. Two G6s with either ammonia core (G6A) or with ethylenediamine core (G6E), which possessed 192 and 256 exterior primary amino groups, respectively, were used. These dendrimers were reacted with 2-(p-isothiocyanatobenzyl)-6-methyl-diethylenetriaminepentaacetic acid (1B4M). The G6--1B4M conjugates were reacted with (153)Gd for studying biodistribution and blood clearance or Gd(III) for the MRI study. 3D-micro-MR angiography of the mice were taken with injection of 0.033 mmol of Gd/kg of G6A--(1B4M-Gd)(192) or G6E--(1B4M-Gd)(256) using a 1.5-T superconductive MRI unit. Although numerous fine vessels of approximately 100 microm diameter were visualized on subtracted 3D-MR-angiography with both G6A--(1B4M-Gd)(192) and G6E--(1B4M-Gd)(256), (153)Gd-labeled saturated G6E-(1B4M)(256) remained in the blood significantly more than (153)Gd-labeled saturated G6A--(1B4M)(192) at later than 15 min postinjection (p < 0.01). In addition, G6E--(1B4M-Gd)(256) visualized these finer vessels longer than G6A--(1B4M-Gd)(192). The G6A--(1B4M-Gd)(192) showed higher signal intensity in the kidney on the dynamic MR images and brighter kidney images than G6E--(1B4M-Gd)(256). In conclusion, the G6A--(1B4M-Gd)(192) was observed to go through glomerular filtration more efficiently than G6E--(1B4M-Gd)(256) resulting faster clearance from the blood and higher renal accumulation, even though both of G6--1B4M conjugates have almost similar molecular size and same chemical structure. In terms of the ability of intravascular contrast agents, G6E--(1B4M-Gd)(256) was better due to more Gd(III) atoms per molecule and longer retention in the circulation than G6A--(1B4M-Gd)(192).

Ammonia↗
PubMedDate not supplied

Avidin-dendrimer-(1B4M-Gd)(254): a tumor-targeting therapeutic agent for gadolinium neutron capture therapy of intraperitoneal disseminated tumor which can be monitored by MRI.

Peritoneal carcinomatosis is a late stage in cancer progress, for which no effective therapeutic modality exists. Targeting therapeutic agents to disseminated lesions may be a promising modality for treating peritoneal carcinomatosis. Gadolinium ((157,155)Gd) is known to generate Auger and internal conversion electrons efficiently by irradiation with a neutron beam. Auger electrons from neutron-activated Gd(III) are strongly cytotoxic, but only when Gd(III) atoms have been internalized into the cells. In the present investigation, we have developed a quickly internalizing tumor-targeting system to deliver large quantities of Gd(III) atoms into tumor cells to generate the Auger emission with an external neutron beam. Simultaneously, one would be able to image its biodistribution by MRI with a shortened T1 relaxation time. Avidin-G6-(1B4M-Gd)(254) (Av-G6Gd) was synthesized from generation-6 polyamidoamine dendrimer, biotin, avidin, and 2-(p-isothiocyanatobenzyl)-6-methyl-diethylenetriaminepentaacetic acid (1B4M). The Av-G6Gd was radiolabeled with Gd(III) doped with (153)Gd. All of the 1B4M's on the conjugate were fully saturated with Gd(III) atoms. An in vitro internalization study showed that Av-G6Gd accumulated and was internalized into SHIN3 cells (a human ovarian cancer) 50- and 3.5-fold greater than Gd-DTPA (Magnevist) and G6-(1B4M-Gd)(256) (G6Gd). In addition, accumulation of Gd(III) in the cells was detected by the increased signal on T1-weighted MRI. A biodistribution study was performed in nude mice bearing intraperitoneally disseminated SHIN3 tumors. Av-G6Gd showed specific accumulation in the SHIN3 tumor (103% ID/g) 366- and 3.4-fold greater than Gd-DTPA (0.28% ID/g, p < 0.001) and G6Gd (30% ID/g, p < 0.001) 1 day after i.p. injection. Seventy-eight percent of the tumor-related radioactivity of Av-G6Gd in the SHIN3 tumor was located inside the cells. The SHIN3 tumor-to-normal tissue ratio was greater than 17:1 in all organs and increased up to 638:1 at 1 day after i.p. injection. In conclusion, a sufficient amount (162 ppm) of Av-G6Gd was accumulated and internalized into the SHIN3 cells both in vitro and in vivo to kill the cell using (157/155)Gd with external irradiation with an appropriate neutron beam while monitoring with MRI. Thus, Av-G6Gd may be a promising agent for Gd neutron capture therapy of peritoneal carcinomatosis. This reagent also has the potential to permit monitoring of its pharmacokinetic progress with MRI.

Animals↗
PubMedDate not supplied

Computed tomography of hydrosalpinx following tubal ligation.

The CT findings in three cases of surgically proven hydrosalpinx following tubal ligation are described. In every case a cystic mass of characteristic tubular shape was detected in the pelvic adnexal region. These findings can be considered diagnostic of iatrogenic hydrosalpinx.

Adult↗
PubMedDate not supplied

MR imaging of cavernous hemangioma of the face and neck.

Four patients with cavernous hemangioma of face and neck were evaluated with magnetic resonance imaging. Pathologically, soft tissue cavernous hemangiomas are characterized by small feeding arteries and large blood poolings. Arteriography usually fails to demonstrate the extent of the lesion. Computed tomography does not allow differentiation between these lesions and surrounding normal tissues. Magnetic resonance clearly demonstrates hemangiomas with good contrast between lesion and normal tissues. Spin-echo technique with long echo time appears to be particularly useful to delineate these lesions.

Adolescent↗
PubMedDate not supplied

Anterior and posterior lobes of the pituitary gland: assessment by 1.5 T MR imaging.

Pituitary glands of 60 normal volunteers (30 men 20-36 years old, and 30 women 18-42 years old) were studied by 1.5 T magnetic resonance (MR) imaging. The T1-weighted images (T1WI) [repetition time (TR) = 400 ms; echo time (TE) = 25 ms] were obtained in the coronal, sagittal, and axial planes. Proton density (PD)/T2-weighted images (PDWI/T2WI) (TR = 2,000 ms; TE = 25/100 ms) were obtained in the sagittal plane using 3 mm slice thickness. On T1WIs of all subjects the posterior part (PP) of the pituitary fossa showed the highest signal, which was indistinguishable from fatty tissue. This study reveals that this region of high signal intensity (PP) corresponds to the posterior lobe and not intrasellar fat because its shape, size, and position are compatible with the posterior lobe; its signal intensity differs from that of fatty tissue on PDWI and T2WI; the absence of an intrinsic chemical shift artifact (CSA) characteristic of fat; and due to CSA, a dorsum with fatty marrow is shifted relative to the PP (or may be made to merge with it). Regarding the differentiation of the two lobes of the pituitary gland on MR, the morphology of the anterior and posterior lobes was evaluated and great variation found. Appreciation of normal is particularly important in evaluating coronal images for small pituitary lesions.

Adolescent↗
PubMedDate not supplied

Posterior lobe of the pituitary in diabetes insipidus: MR findings.

The posterior lobe of the pituitary gland was evaluated by 1.5 T magnetic resonance (MR) in five cases of diabetes insipidus (DI), including one primary (idiopathic) and four secondary DI cases due to germinomas (two), teratoma (one), and histiocytosis X (one). The normal posterior lobe displays high signal indistinguishable from fatty tissue on T1-weighted images (T1WI) (short T1 value). In all five DI cases the normal high signal of the posterior lobe was not detected in the pituitary fossa on T1WI. Hence, because of this characteristic finding, MR may greatly assist in the diagnosis of DI. We may speculate that the short T1 value of the posterior lobe is closely related to its functional integrity and may be due to the neurosecretory materials in the axons of the hypothalamohypophyseal tract.

Adolescent↗
PubMedDate not supplied

MR imaging of the sellar spine.

Magnetic resonance images of two cases of sellar spine are reported. The sellar spine is an anatomical variant characterized by an osseous spine that arises in the midline from the dorsum sellae and protrudes into the pituitary fossa. On short repetition time/short echo time (T1-weighted) images the sellar spine is demonstrated as a hypointense structure within the high intensity posterior pituitary. We suggest that the sellar spine is the ossified remnant of the cephalic tip of the notochord.

Adult↗
PubMedDate not supplied

MR imaging of gynecologic lymphoma.

We present a case of solitary secondary gynecologic lymphoma, in which MR imaging contributed to the diagnosis. The finding was a region of uterine enlargement consisting of ill-defined nodules of variable signal intensity diffusely mixed with the myometrium.

Aged↗
PubMedDate not supplied

Intravenous leiomyomatosis of uterus: MR appearance.

We report a case with intravenous leiomyomatosis of uterus that showed characteristic appearances on MR. Magnetic resonance demonstrated a tangle of distended and folded tubular structures, well enhanced by Gd-diethylenetriamine pentaacetic acid. It was confirmed by surgery that these tubular structures reflected the vessels markedly dilated by intravascular tumor.

Adult↗
PubMedDate not supplied

Uterine deformity caused by surgery during pregnancy.

OBJECTIVE: The purpose of our study was to determine the cause of a unique deformity of the uterus, in which the cervix is elongated and appears fixed to the anterior abdominal wall. MATERIALS AND METHODS: Imaging from 2,558 consecutive MR studies of the pelvis of women were retrospectively reviewed for the simultaneous presence of elongation of the uterine cervix, angulation of the uterine isthmus just beneath the anterior abdominal wall, and vertical orientation of the long axis of the uterine corpus. RESULTS: Fourteen cases exhibited the uterine deformity; 13 of these cases had histories of cesarean section (CS) performed from 9 to 33 years (mean 18.2 years) previous to MRI. Among them, six patients had a history of multiple CS. The remaining case had a history of enucleation at 13 weeks' gestation of uterine leiomyoma, located at the anterior wall of the lower uterine segment. Thirteen patients had not become pregnant after the last CS (no. = 12) or the myomectomy (no. = 1). CONCLUSION: This unique uterine deformity strongly indicates a history of incision in the lower uterine segment especially at late gestational age. Since all but one patient with this deformity did not become pregnant after the last surgery, this deformity may be one reason for infertility after CS.

Abdominal Muscles↗