Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Hiroki Imazu is active.

Publication


Featured researches published by Hiroki Imazu.


Journal of Gastroenterology | 2001

Psoas abscess and cellulitis of the right gluteal region resulting from carcinoma of the cecum

Hidetaka Kobayashi; Yoichi Sakurai; Mitsutaka Shoji; Yasuko Nakamura; Masashi Suganuma; Hiroki Imazu; Shigeru Hasegawa; Toshiki Matsubara; Masahiro Ochiai; Takahiko Funabiki

Although retroperitoneal or psoas abscess is an unusual clinical problem, the insidious and occult characteristics of this abscess sometimes cause diagnostic delays, resulting in considerably high morbidity and mortality. In particular, psoas abscess caused by perforated colon carcinoma is uncommon. We report a case of psoas abscess caused by a carcinoma of the cecum. A 72-year-old Japanese woman was admitted to our hospital, with pain in the right groin and buttock. The pain had appeared 6 months before admission, and the symptoms had then been relieved by oral antibiotics. On March 25, 1999, inflammatory signs in the right buttock indicated localized cellulitis, and incision and drainage was performed at a local hospital. The patient was referred to our hospital on the same day. On admission to our hospital, computed tomography (CT) scan revealed a thick right-sided colonic wall and enlargement of the right ileopsoas muscle. Barium enema and colonofiberscopy revealed an ulcerated tumor occupying the entire circumference of the cecum. A retroperitoneal abscess and fistula had been formed by the retroperitoneal perforation of cecum carcinoma: surgical resection was performed after remission of the local inflammatory signs. Operative findings indicated that the cancerous lesion and its surrounding tissues were firmly attached to the right iliopsoas and major psoas muscle, and en-bloc resection, including adjacent muscular tissue, was performed. The fact that carcinoma of the colon could be a cause of psoas abscess and cellulitis in the gluteal region should be considered when an unexplained psoas abscess is diagnosed.


Journal of Gastroenterology | 2004

Perforated duodenal diverticulum successfully diagnosed preoperatively with abdominal CT scan associated with upper gastrointestinal series

Yoichi Sakurai; Hirotake Miura; Toshiki Matsubara; Hiroki Imazu; Shigeru Hasegawa; Masahiro Ochiai

Although duodenal diverticulum is not uncommon, precise preoperative diagnosis is occasionally difficult. We report a patient with perforated duodenal diverticulum successfully diagnosed preoperatively by an upper gastrointestinal series followed by abdominal computed tomography (CT) scanning. An 81-year-old Japanese woman visited a local hospital because of right-sided abdominal pain. Physical examination revealed diffuse muscle guarding localized in the entire right-side of the abdomen indicative of peritonitis. While plain abdominal X-ray film revealed no free air, abdominal ultrasound and abdominal CT scanning revealed fluid collection and gas in the anterior perirenal space. An emergency upper gastrointestinal series, using water-soluble contrast media, demonstrated multiple diverticula in the descending portion and the horizontal portion of the duodenum. Leakage of the contrast material was found by the upper gastrointestinal series followed by the abdominal CT scanning, suggesting that the peritonitis was caused by the perforated duodenal diverticulum, and an emergency laparotomy was performed. The diverticulum in the descending portion of the duodenum was mobilized from the retroperitoneum and complete resection and peritoneal drainage were performed. The resected specimen showed that the diverticulum was 42 × 23 mm in size, and two separate sites of perforation were identified. The present case suggests that upper gastrointestinal series followed by CT scan is useful for the preoperative diagnosis of perforated duodenal diverticulum.


Surgery Today | 2000

Metastasis to the Forearm Skeletal Muscle from an Adenocarcinoma of the Colon: Report of a Case

Shigeru Hasegawa; Yoichi Sakurai; Hiroki Imazu; Toshiki Matsubara; Masahiro Ochiai; Takahiko Funabiki; Katsuji Suzuki; Yoshikazu Mizoguchi; Makoto Kuroda; Masao Kasahara

Abstract While the liver and lung are primary targets for distant metastasis from colorectal carcinoma, metastasis in other distant sites is rarely found. We report herein an unusual case of metastasis to the skeletal muscle of the right forearm from an adenocarcinoma of the transverse colon. A 60-year-old man was originally admitted to our hospital for surgical treatment of an intestinal obstruction caused by a transverse colon carcinoma. Transverse colon resection along with lymph node dissection was performed and no evidence of distant metastatic foci was found. Angiography-enhanced computed tomography scanning done 14 months after the first operation revealed multiple hepatic metastases which were resected. A metastasis was subsequently detected in the right extensor carpi ulnaris muscle 2 years after the primary resection, and a major part of the right extensor carpi ulnaris and the extensor digiti minimi muscle were resected, warranting a sufficient margin of 5 cm of normal tissue from the tumor. Reattachment of the residual muscles into the ulna was performed. Metastases to bone and/or soft tissues from colorectal carcinomas are extremely rare and to our knowledge, only eight other cases have been reported in the world literature. This low incidence may be related to the anatomical characteristics and/or the biochemical environment of the skeletal muscle, but it is also possible that the true incidence is underestimated. Recent improvements in interventional radiological procedures may facilitate a diagnosis of skeletal muscle metastasis being made more frequently.


Surgery Today | 2002

Multiple perforated ulcers of the small intestine associated with allergic granulomatous angiitis: report of a case.

Yasuko Nakamura; Yoichi Sakurai; Toshiki Matsubara; Tomohito Nagai; Shusaku Fukaya; Hiroki Imazu; Shigeru Hasegawa; Masahiro Ochiai; Takahiko Funabiki; Yoshikazu Mizoguchi; Makoto Kuroda

Although allergic granulomatous angiitis (AGA) is occasionally associated with gastrointestinal lesions, multiple perforated ulcers of the gastrointestinal tract are uncommon. We report herein a case of AGA associated with multiple perforated ulcers that erupted in the small intestine during corticosteroid therapy. A 31-year-old Japanese man was admitted to our hospital with epigastralgia, edema of the bilateral lower extremities, and general malaise. He had a persistent high fever, abdominal pain, and watery diarrhea. Laboratory data showed remarkable eosinophilia. The abdominal pain became exacerbated after the administration of oral prednisolone. Physical examination indicated positive signs of peritoneal irritation in the entire abdomen, and abdominal computed tomography scanning showed intra-abdominal free air, suggesting generalized peritonitis due to intestinal perforation. Laparotomy revealed multiple perforated ulcers in the jejunum and ileum. Histological examination indicated remarkable eosinophilic infiltration in the surrounding area of the small arteries and arterioles located in the submucosal layer, which was compatible with AGA. Although the association of intestinal perforation with AGA is relatively infrequent, intensive perioperative management is essential to ensure a favorable clinical outcome, particularly during the period on corticosteroid therapy.


Journal of Hepato-biliary-pancreatic Surgery | 1997

Biliary carcinogenesis in pancreaticobiliary maljunction

Takahiko Funabiki; Toshiki Matsubara; Masahiro Ochiai; Yoshihisa Marugami; Yoichi Sakurai; Shigeru Hasegawa; Hiroki Imazu

The coexistence of bile duct carcinoma in choledochal cysts is well known. With large number of cases of congenital bile duct dilatation and pancreaticobiliary maljunction (PBM), it is now apparent that gallbladder carcinoma is more frequent in PBM without bile duct dilatation. The incidence of Gallbladder cancer in choledochal cyst and bile duct cancer in PBM, regardless of the presence of bile duct dilatation is significantly higher than that in control patients with biliary cancer but without PBM. A recent survey shows that the incidence of bile duct cancer in PBM without dilatation is equivalent to that of gallbladder cancer and bile duct cancer in patients with choledochal dilatation. Pathology in PBM is a result of reflux of pancreatic juice and stasis of the mixture in the biliary system. Carcinogenic factors thus present in the biliary contents induce epithelial changes in the biliary tract. In the biliary contents, activated pancreatic enzymes and secondary or deconjugated bile acids are markedly increased and they irritate the biliary mucosa. Mutagens are proven to form in the bile of PBM. In the epithelia of PBM, hyperplasia, metaplasia, and dysplasia are often found, and proliferative activity is increased; furthermore, K-ras gene mutation and overexpression of p53 protein are demonstrated. As for treatment of PBM, whether it is symptomatic or not, an operative procedure, is necessary, to prevent carcinogenic changes in the gallbladder and bile duct. Regardless of whether dilatation is present or not, total excision of the extrahepatic bile duct, along with gallbladder, is the treatment of choice, followed by hepaticojejunostomy or hepaticoduodenostomy.


Journal of Gastroenterology | 1997

Cardiac metastasis from squamous cell carcinoma of gallbladder

Masashi Suganuma; Yoshihisa Marugami; Yoichi Sakurai; Masahiro Ochiai; Shigeru Hasegawa; Hiroki Imazu; Toshiki Matsubara; Takahiko Funabiki; Makoto Kuroda

A 65-year-old woman was admitted to our hospital with the diagnosis of gallbladder tumor. Right extended hepatic lobectomy plus lymph node dissection of the hepatoduodenal ligament and left hepaticojejunostomy with Roux-en-Y reconstruction was performed in July, 1993. The gallbladder tumor was histologically proven to be squamous cell carcinoma. Seventeen months later, the patient experienced dyspnea and pitting edema of the lower legs and was admitted, in December 1994, with a diagnosis of heart failure. Despite intensive cardiac support, she died 12 days after the second admission. Autopsy revealed multiple cardiac tumors in the left and right ventricles, left atrium, left coronary artery, and left diaphragm. Histologically, these tumors were shown to be squamous cell carcinoma, considered to have metastasized from the primary gallbladder carcinoma. As neither local recurrence of the gallbladder carcinoma. As neither local recurrence of the gallbladder carcinoma nor any lymph node metastasis was found, the cardiac metastasis of the gallbladder carcinoma may have occurred via the hematogenous route. Although rare, this route of cardiac metastasis of gallbladder carcinoma may be an important aspect of distant metastasis, which should be monitored for during follow-up after resection of the primary tumor.


Journal of Gastroenterology | 1995

Intrahepatic sarcomatous cholangiocarcinoma

Hiroki Imazu; Masahiro Ochiai; Takahiko Funabiki

A 77-year-old man, diagnosed with a liver tumor, was referred to our hospital. Abdominal ultrasonography demonstrated a low echoic mass in the liver S2 region, and abdominal CT confirmed the presence of a round low-density mass 7 cm in diameter. Enhanced angio-computed tomography (CT) showed a ring-like form with a pale periphery. In the delayed phase of angio-CT, the inside of the mass was enhanced, showing septal stricture. Abdominal magnetic resonance imaging (MRI) revealed a heterogenous low intensity area in T1-weighted images, with a clear high intensity border becoming apparent in T2-weighted images. Stretching of the hepatic artery was evident on the arterial phase of angiography, while an avascular area was apparent in the lateral segment of the liver in the portal phase. Lateral segmentectomy was performed. The size of the tumor was 6×6×5 cm. On macroscopic cross section, it was white and clearly demarcated from the surrounding tissue. Microscopic observation of H&E-stained specimens did not show any glandular formation. The tumor consisted of an irregular fascicular arrangement of spindle-shaped and round cells with poor intercellular adhesion. While there was no region containing differentiated epithelial components, silver impregnation staining revealed structures resembling regenerating bile ducts. The tumor cells were positive for wide-keratin, and for vimentin staining. Tumor cells were carcinoembryonic antigen (CEA)-positive and alpha-feto protein (AFP)-negative. From the above findings, the tumor was judged to have originated from epithelium rather than from mesenchymal elements. The final diagnosis was intrahepatic cholangiocarcinoma with secondary sarcomatous transformation, rather than hepatocellular carcinoma.


Surgery Today | 2000

Submucosal Dermoid Cyst of the Rectum: Report of a Case

Yoichi Sakurai; Takashi Uraguchi; Hiroki Imazu; Shigeru Hasegawa; Toshiki Matsubara; Masahiro Ochiai; Takahiko Funabiki

Despite the relatively common incidence of sacrococcygeal dermoids, rectal cysts are uncommon. We report the case of a submucosal dermoid cyst occurring in the rectum. A 30-year-old woman visited the Gynecology Department because of pregnancy. A pelvic tumor was accidentally found during the checkup after miscarriage. A barium enema showed an anterior shift of the rectum by the presence of the tumor. Computed tomography and magnetic resonance imaging revealed a tumor located posterior to the rectum occupying almost the entire pelvic cavity, and the tumor was resected. The tumor was located in the submucosal layer of the posterior rectal wall and was well circumscribed. The resected tumor was a cyst entirely covered with a fibrous and firm capsule, which was filled with an amorphous white creamy substance. The histological findings showed the cyst consisting of a keratinizing stratified squamous epithelium with sebaceous gland and hair follicles, which was compatible with benign cystic teratoma. Primary rectal teratoma is very rare and only 36 cases have been reported in the literature worldwide. Furthermore, while the majority of cases were polypoid-shaped dermoid cysts protruding into the rectal lumen, only 3 cases were submucosal dermoid cysts. Therefore, such cases are considered to be extremely rare.


Pathology International | 2000

Angiomyomatous hamartoma and associated stromal lesions in the right inguinal lymph node: A case report

Yoichi Sakurai; Mitsutaka Shoji; Toshiki Matsubara; Hiroki Imazu; Shigeru Hasegawa; Masahiro Ochiai; Takahiko Funabiki; Yoshikazu Mizoguchi; Makoto Kuroda; Masao Kasahara

Angiomyomatous hamartoma is a rare disease with a predisposition for the inguinal lymph nodes. A 51‐year‐old male patient visited a local hospital because of a right inguinal mass, measuring 3 × 4 cm in size, which was resected. The resected specimen showed irregularly distributed thick‐walled vessels in the hilum, extending into the medulla and focally into the cortex of the node, eventually becoming more dispersed and associated with smooth muscle cells splaying into sclerotic stroma. These findings are compatible with an angiomyomatous hamartoma. Another tumor‐like mass appeared shortly after the resection at the same location, but was not an angiomyomatous hamartoma, rather it was composed of edematous stromal tissue with proliferating smooth muscle cells. The stromal component included thick‐walled blood vessels and lymphatics. Although it could not be determined whether these associated changes in the surrounding stroma are a cause or an effect of angiomyomatous hamartoma, they indicate the clinical difficulty in determining an appropriate area of resection and may provide clues to the pathogenesis of angiomyomatous hamartoma.


Gastric Cancer | 2004

Changes in thymidylate synthase and its inhibition rate and changes in dihydropyrimidine dehydrogenase after the administration of 5-fluorouracil with cisplatin to nude mice with gastric cancer xenograft SC-1-NU

Yoichi Sakurai; Takashi Uraguchi; Hiroki Imazu; Shigeru Hasegawa; Toshiki Matsubara; Masahiro Ochiai; Takahiko Funabiki

BackgroundAlthough 5-fluorouracil (5-FU) and cis-diamminedichloroplatinum (cisplatin) in combination have synergistic cytotoxicity against both murine and human neoplasms, the precise mechanism of the synergism, and the effects on thymidylate synthase and its percent inhibition, and the effects on dihydropyrimidine dehydrogenase (DPD) remained to be elucidated.MethodsExperimental chemotherapy was performed using SC-1-NU, a human gastric carcinoma xenograft. SC-1-NU was maintained by serial transplantation in male BALB/c nude mice. The nude mice received various chemotherapeutic regimens consisting of 5-FU and/or cisplatin, with different dosages and periods of administration. After the treatment, we examined the in vivo effects of 5-FU and cisplatin in each regimen on thymidylate synthase and its percent inhibition, and the effects on DPD, in addition to the observation of tumor growth inhibition.ResultsThe combined use of 5-FU (20 mg/kg per day) and cisplatin (either 1.5 or 7.5 mg/kg per day) showed a synergistic antitumor effect, regardless of the different doses of cisplatin. The long-term administration of 5-FU significantly increased both total thymidylate synthase and the percent thymidylate synthase inhibition rate. The short-term administration of 5-FU significantly decreased DPD. Nevertheless, these changes showed no relation to the combined use of cisplatin.ConclusionCombined administration of cisplatin with 5-FU did not further increase thymidylate synthase inhibition over that occurring with 5-FU alone, which does not support the hypothesis that cisplatin combined with 5-FU modulates thymidylate synthase inhibition in enhancing the anticancer effect of 5-FU. Changes in DPD after the administration of 5-FU may provide an insight into tumor sensitivity and resistance to 5-FU.

Collaboration


Dive into the Hiroki Imazu's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Yoichi Sakurai

Fujita Health University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Toshiki Matsubara

Memorial Hospital of South Bend

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Makoto Kuroda

Fujita Health University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge