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Biomedical subjects

W T Yang

Publications and source records attributed to W T Yang.

At least 37 records · Page 2Linked to original sources
PubMed1999

Ultrasound, CT and colonoscopy of colonic cancer.

Barium enema and colonoscopy are commonly used for the investigation of suspected colonic cancer. These techniques are relatively invasive and both the investigation and the preceding bowel preparation are demanding, particularly in the elderly. A prospective, blinded trial was conducted to compare ultrasound (US) and CT with colonoscopy. CT and colonoscopy were performed on 50 patients with symptoms suggesting colonic cancer. Both radiological investigations were performed prior to the bowel preparation for colonoscopy. US was performed without any preparation and oral contrast medium was the only preparation used for CT. Colonoscopy detected six cancers, all of which were diagnosed by both US and CT. In addition, US and CT diagnosed a further cancer not seen on colonoscopy due to an incomplete study. US had a sensitivity and specificity of 100% and CT a sensitivity of 100% and a specificity of 84%. US and CT were poor at diagnosing polyps. If the detection of polyps greater than 2 cm is included then US sensitivity falls to 67% and CT sensitivity falls to 89% and specificity rises to 88%. In conclusion, both US and CT are possible alternatives to colonoscopy in the investigation of symptomatic patients with suspected colonic cancer. The use of these techniques could markedly reduce the need for colonoscopy in this patient population with attendant cost savings. Non-invasive imaging has particular advantages in the elderly who cope poorly with both the bowel preparation and the procedure.

Adult↗
PubMed1999

Comparison of laparoscopic sonography with surgical pathology in the evaluation of pelvic lymph nodes in women with cervical cancer.

OBJECTIVE: This study compared laparoscopic sonography with surgical pathology in the evaluation of pelvic lymph nodes in women with cervical cancer. SUBJECTS AND METHODS: Intraoperative laparoscopic sonography of pelvic lymph nodes was performed in 31 women with biopsy-proven cervical cancer. A lymph node that was rounded (longitudinal-transverse axis ratio of <2) or showed absence of central hilum was defined as positive for metastasis. For comparison, lymph nodes from each hemipelvis were grouped anatomically into paraaortic, common, internal, and external iliac chains during evaluation on laparoscopic sonography and on surgical pathologic examination. RESULTS: Pelvic dissection in 31 women yielded 630 lymph nodes. There were 54 metastatic nodes in 12 women. Laparoscopic sonography revealed 32 (59%) of all pathologically metastatic lymph nodes. Sensitivity on laparoscopic sonography when comparing groups by hemipelves was 93.3% and by anatomic lymph node chains was 76.2%. Metastatic nodes were most commonly located in the common iliac region and were characteristically rounded, hypoechoic, showed absence of central hilum, and occasionally showed central necrosis. Nine (28%) of 32 metastatic lymph nodes revealed by laparoscopic sonography measured 1 cm or less. Six benign nodes in four patients were also visualized with laparoscopic sonography. CONCLUSION: Laparoscopic sonography achieved a sensitivity exceeding 90% in the detection of metastatic lymph nodes in the hemipelves of women with cervical cancer. Laparoscopic sonography is a feasible and promising technique for the evaluation of pelvic lymph nodes in women with cervical cancer and merits further evaluation.

Adult↗
PubMed1998

New development of laparoscopic ultrasound and laparoscopic pelvic lymphadenectomy in the management of patients with cervical carcinoma.

OBJECTIVES: The objectives of this study were to evaluate the use of laparoscopic ultrasonography (USG) in combination with laparoscopic pelvic lymphadenectomy in the management of patients with cervical carcinoma. METHODS: A technique for detecting pelvic and para-aortic lymph node metastases through laparoscopic USG was developed. Laparoscopic USG was done prior to pelvic lymphadenectomy performed either laparoscopically or by laparotomy. Laparoscopic USG findings were compared with pathologic findings. RESULTS: The sensitivity and specificity of laparoscopic USG in detecting pelvic lymph node metastases were 91 and 100%, respectively. Metastatic pelvic lymph nodes could be completely removed through laparoscopes in 7 of 11 patients, with no complications. CONCLUSION: Laparoscopic USG is highly sensitive in detecting metastatic pelvic lymph nodes. Detection and removal of metastatic pelvic lymph nodes laparoscopically allow quick recovery from the operation and early commencement of radiotherapy.

Adult↗
PubMed1998

Hepatobiliary rhabdomyosarcoma in children: diagnostic radiology.

Rhabdomyosarcoma (RMS) occurs infrequently in the liver and biliary tree. Although the radiological diagnosis may be simple when the tumour involves the extrahepatic bile ducts, no specific imaging features are known for hepatic RMS. We present four cases and discuss the role of diagnostic radiology in the management of this tumour.

Biliary Tract Neoplasms↗
PubMed1998

Spontaneous intramural haematoma of the oesophagus: CT and MRI appearances.

A 64-year-old man with history of ischaemic heart disease and coronary artery bypass graft surgery, but no history of peptic ulcer or liver disease, presented with retrosternal pain and coffee-ground vomitus. Endoscopy revealed a long column of bluish discolouration with normal mucosa interpreted as a grade IV oesophageal varix. Computed tomography showed a non-enhancing low-density submucosal columnar lesion in the mid- and lower oesophagus consistent with a submucosal haematoma. This resolved on follow-up at 10 days. The magnetic resonance features of intermediate signal intensity on T1-weighted images and hyperintense signal on T2-weighted images of this lesion are also highlighted.

Esophageal Diseases↗
PubMed1998

Hepatic hemangioma: quantitative color power US angiography--facts and fallacies.

PURPOSE: To explore the origin of signals detected with color power ultrasound (US) angiography (CPA) and evaluate a semiquantitative method to assess signals in hepatic hemangiomas. MATERIALS AND METHODS: Twenty-four adult patients with 27 hepatic hemangiomas (< 2 cm in diameter) and five patients with five hyperechoic hepatic metastases underwent CPA and conventional color Doppler US in this prospective study. A sponge phantom was studied to determine whether the origin of CPA signals was related to architecture. The mean number of signals and the signal density in each lesion were scored. RESULTS: A "diffuse blush" was seen in all capillary hemangiomas at CPA, whereas no signal was seen at color Doppler US. The sponge phantom test produced a CPA appearance similar to that of capillary hemangiomas. Quantitative analysis of CPA images of hepatic hemangiomas showed a mean of 16.1 signals per cubic centimeter and a mean signal area of 25%. Hyperechoic avascular hepatic metastases resulted in CPA images similar to those of hepatic hemangiomas, with no quantitative difference in signal count, despite a mild qualitative difference at CPA. CONCLUSION: CPA signals in hepatic hemangiomas appear to be related more to architecture than to true capillary flow. There is a qualitative difference in the strength of the blush at CPA between hepatic hemangiomas and metastases, which may be the only possible differentiating factor.

Adult↗
PubMed1998

Colour Doppler flow in normal axillary lymph nodes.

81 women with carcinoma of the breast who underwent axillary nodal dissection were studied pre-operatively with colour Doppler ultrasound. The presence of colour Doppler flow was demonstrated in 83.6% of normal lymph nodes compared with 87.5% of metastatic lymph nodes. Using the presence of colour Doppler signal as the sole diagnostic criterion for the diagnosis of metastasis gave a sensitivity of 92.5%, specificity of 9.52%, accuracy of 50%, positive predictive value of 49.3% and negative predictive value of 57.1%. Using grey scale sonographic criteria, where a metastatic node was defined as a node with loss of central fatty hilum and/or eccentric cortical hypertrophy, a sensitivity of 79.5%, specificity of 94.0%, accuracy of 87.6%, positive predictive value of 91.2% and negative predictive value of 85.5% were obtained. Colour Doppler studies of the axillary nodes in a second group of 106 women who attended for breast cancer screening and had no significant breast or axillary pathology also showed colour Doppler signal in 86.7% of nodes. It is concluded that colour Doppler flow signals can be demonstrated in both normal and metastatic axillary lymph nodes, and is highly non-specific when used as the sole diagnostic criterion in the diagnosis of malignancy.

Axilla↗
PubMed1998

Anatomy of the normal brachial plexus revealed by sonography and the role of sonographic guidance in anesthesia of the brachial plexus.

OBJECTIVE: The purpose of this study is to describe the sonographic appearance of the normal brachial plexus and to evaluate the use of imaging guidance for brachial plexus anesthesia. SUBJECTS AND METHODS: Twenty adults requiring upper limb surgery underwent sonography with a high-frequency transducer to identify the brachial plexus at the interscalene (n = 16) and supraclavicular (n = 4) regions. Catheters for brachial plexus anesthesia were placed using sonographic guidance and evaluated using radiography and CT after injection of contrast material. The success of the neural blockade and surgical anesthesia was assessed. General anesthesia was chosen preoperatively or used for supplementation if blockade was incomplete. RESULTS: The brachial plexus appeared as three discrete rounded hypoechoic nodules between the scalenus anterior and medius muscles on transverse sonography at the lower cervical (C6) region, representing the trunks in sagittal oblique section. A cluster of hypoechoic nodules corresponding to the divisions was seen cephalad to the subclavian artery on sagittal scans of the supraclavicular region. Radiography was used to verify correct catheter placement; the brachial plexus sheath appeared as a tubular area of contrast material in the neck that was well circumscribed in patients who had supraclavicular injections of contrast material and corrugated in those who had interscalene injections. CT scans showed contrast material spread around the scalenus muscles in most patients with interscalene injections. Successful neural blockade at 20 min and postoperative analgesia were achieved in all patients. Surgical anesthesia was achieved in nine of 15 patients. Five patients chose general anesthesia before surgery and therefore did not have surgical anesthesia assessed. CONCLUSION: High-resolution sonography can show normal brachial plexus anatomy and facilitate catheter-based brachial plexus anesthesia without complications.

Adolescent↗
PubMed1998

Intraoperative laparoscopic sonography for improved preoperative sonographic pathologic characterization of adnexal masses.

This study compares the diagnostic accuracy of laparoscopic sonography and transvaginal sonography in the evaluation of adnexal masses. Fifty-eight women underwent transvaginal sonography, which showed 69 adnexal masses, and laparoscopic ultrasonography, which showed 68 adnexal lesions. Conventional gray-scale ultrasonography (using transvaginal sonography and laparoscopic ultrasonography) was performed with morphologic characterization of internal architecture, followed by color Doppler imaging with spectral Doppler analysis where possible. A specific diagnosis was obtained with transvaginal sonography and laparoscopic ultrasonography based on a combination of imaging features. The specific diagnosis obtained with each imaging modality was compared with the final histologic diagnosis as the gold standard in 57 patients with 68 adnexal masses who underwent cystectomy or oophorectomy. The ability of laparoscopic sonography to detect the contralateral ovary and any residual ovarian tissue in the presence of a mass was also compared with transvaginal sonography. The accuracy of laparoscopic ultrasonography in the characterization of adnexal masses was 83.8% and that of transvaginal sonography was 73.5% (P < 0.05). Laparoscopic sonography showed greater morphologic detail than that obtained with transvaginal sonography, allowed more precise and specific characterization of adnexal masses, and detected additional adnexal lesions not evident on preoperative transvaginal sonography. Laparoscopic ultrasonography showed the contralateral ovary in 86.2% of patients, compared with 81.0% using transvaginal sonography (P = 0.51). In addition, laparoscopic ultrasonography was able to demonstrate the presence of residual ovarian tissue in the side affected pathologically in 76.5% of patients compared with 59.4% using transvaginal sonography (P < 0.005). Laparoscopic sonography allows more precise morphologic characterization of internal architecture and histologic diagnosis of adnexal lesions, but it is as yet unable to increase the diagnostic accuracy of borderline or malignant lesions, possibly due to the small sample size. Laparoscopic sonography is superior to transvaginal sonography in the evaluation of residual ovarian tissue in the side affected pathologically, which may help in surgical planning between cystectomy and oophorectomy, and also in the identification of the contralateral ovary, which may potentially increase the detection of bilateral pathologic conditions.

Adnexal Diseases↗
PubMed1997

Benign giant cell tumor of bone with osteosarcomatous transformation ("dedifferentiated" primary malignant GCT): report of two cases.

It is not uncommon for sarcomatous transformation of giant cell tumor (GCT) of bone to occur after radiation, but rarely does malignant transformation occur spontaneously, with less than 15 cases reported up to 1995. Only four of these cases have been documented in detail. We report two additional cases of GCT of bone spontaneously transforming or "dedifferentiating" into osteosarcoma without radiation therapy. The first case is absolutely unique and most interesting in that the dedifferentiation process occurred in one of multiple GCT lung metastases 6 years after successful eradication of a primary tibial tumor. The right lung was resected due to development of a large tumor, and at pathologic examination, demonstrated several small nodules of conventional GCT and a much larger, 14-cm mass composed of a mixture of GCT and high-grade osteosarcoma. The second case involved a physician, who had a large tumor in the sacrum with vague symptoms for 8 years. Open biopsy revealed conventional, benign GCT of bone with a secondary aneurysmal bone cyst. Complete curettage 2 weeks later revealed, in addition to areas of conventional, benign GCT a second component of very high grade osteosarcoma. Both patients died less than 1.5 years from diagnosis. This report of osteosarcomatous transformation of a conventional GCT of bone strengthens the theory that there is a mesenchymal cell line in GCT that may spontaneously transform to sarcoma.

Adult↗
PubMed1997

Mammographic, sonographic and histopathological correlation of benign axillary masses.

Eight cases of benign isolated axillary masses due to tuberculous lymphadenitis (3), chronic inflammation (1), accessory axillary breast tissue (3) and lipoma (1) are presented. The mammographic, sonographic and histopathological features are described, differential diagnoses outlined and usefulness of mammography, ultrasound and ultrasound-guided tissue sampling discussed.

Adult↗
PubMed1997

MRI and CT of metastatic hepatocellular carcinoma causing spinal cord compression.

We report the imaging features in five patients with metastatic hepatocellular carcinoma causing spinal cord compression, three of which were biopsy proven and two were in patients with known diagnosis of hepatocellular carcinoma. The radiographic, magnetic resonance imaging (MRI) and computed tomography (CT) features are highlighted. Although the occurrence of metastatic disease in hepatocellular carcinoma is exceedingly rare, it may be increasingly encountered as survival of patients is improved with advancing methods of therapy, both surgical and palliative. It often accompanies local recurrence, and invariably signals a grave prognosis with extremely short life expectancy. Unusually, two of the five patients in this series presented initially with skeletal metastases which led to the diagnosis of hepatocellular carcinoma.

Adult↗
PubMed1997

Plain radiography and computed tomography of invasive thymomas: clinico-radiologic-pathologic correlation.

Fifteen computed tomography (CT) scans in nine patients with invasive thymoma are presented. The CT findings were an anterior mediastinal mass (89%), pleural deposits (78%), local infiltration of the mediastinum (100]), invasion of the cardiovascular structures (22%), lung invasion (11%) and diaphragmatic or subdiaphragmatic deposits (33%). Radiologic-pathologic correlation available in six patients showed a sensitivity of 89.5%, specificity of 87.5% and accuracy of 88.6% for CT. We conclude that CT is superior to plain radiography in the diagnosis of invasive thymoma. It provides an accurate pre-operative assessment by better demonstration of the full extent of abnormalities, and is useful in surgical planning, monitoring of therapeutic response and detecting recurrence.

Adult↗
PubMed1997

Uncommon features of abdominal aortoiliac disease.

This pictorial review illustrates the cross-sectional imaging of several less common manifestations of aortoiliac disease. Despite their varying clinical features, the imaging appearances with ultrasound, CT and MRI will allow a correct assessment in most cases.

Adult↗