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Biomedical subjects

H B Pan

Publications and source records attributed to H B Pan.

At least 19 recordsLinked to original sources
PubMed2001

In vivo proton MR spectroscopy of chorea-ballismus in diabetes mellitus.

The most common cause of chorea-ballismus (CB) is a vascular lesion; it is also associated with nonketotic hyperglycaemia in diabetes mellitus (DM) and may be the first manifestation of this disorder. We describe the CT, MRI and proton MR spectroscopy (1H-MRS) of CB in eight patients. Six had hemichorea-hemiballismus (HC-HB) and two bilateral CB. Single-voxel (SV) 1H-MRS was performed using point-resolved spectroscopy (PRESS). Voxels were positioned in the basal ganglia of the patients and control subjects. PRESS was also used to obtain spectroscopic imaging (1H-MRSI) of the slice of interest in two patients. CT showed a slightly dense striatum in all the patients with CB, and T1-weighted images revealed high signal. The CB correlated well with the neuroimaging findings. SV 1H-MRS showed the mean (+/- SD) N-acetylaspartate (NAA)/ creatine (Cr) ratio to be 1.45 +/- 0.19 in HC-HB and 1.82 +/- 0.06 on the opposite normal side (P = 0.01). The choline (Cho)/ Cr ratio was 1.3 +/- 0.12 in HC-HB and 1.11 +/- 0.13 on the opposite normal side (P = 0.005). A lactate peak was seen in seven patients. The NAA/Cr ratio was 1.44 +/- 0.15 in bilateral CB and 1.74 +/- 0.16 in the controls (P = 0.017); the Cho/Cr ratios were 1.36 +/- 0.1 and 1.19 +/- 0.07 (P = 0.015). The low NAA/Cr suggests neuronal loss or damage and the high Cho/Cr probably indicates gliosis. The presence of lactate may suggest mild ischaemia due to acute vascular events during hyperglycaemia and underlying chronic focal cerebrovascular diseases in DM.

Aged↗
PubMed2001

Solitary fibrous tumor of the liver.

Solitary fibrous tumor of the liver is a rare neoplasm. So far, 21 cases have been described in the English literature. We reported an additional case. Our patient, a 75-year-old man, suffered from abdominal fullness and body weight loss of 6 kg over 6 months, and chills and fever for 2 months. Hypoglycemia was noted at admission. Both abdominal sonography and CT showed a huge mass occupying the right lobe of liver. Liver biopsy showed fibrous tumor. Right lobectomy was performed and the tumor was resected. Pathological examination showed spindle-shaped and fibroblast-like cells within the collagenous stroma. On immunohistochemical stains, these spindle tumor cells showed CD34 positive reactivity. The post-operative course was uneventful and there was no more hypoglycemia. The patient recovered smoothly, regained his body weight, and was alive without evidence of disease recurrence at the last follow-up visit in November, 2000.

Aged↗
PubMed2001

Intramedullary spinal cryptococcoma: a case report.

Intramedullary spinal cryptococcosis is very rare. We describe a case of intramedullary spinal cryptococcoma at the T12 level in a 60-year-old man who presented with a 3-month history of progressive bilateral lower limb weakness and no obvious immunocompromise. Magnetic resonance (MR) imaging revealed a 1.2 cm diameter mass within the spinal cord at T12 with intermediate signal intensity on T1-weighted images, a slight degree of homogeneous low signal intensity on T2-weighted images, and intense enhancement after infusion of gadopentetate dimeglumine. These findings led to a preoperative diagnosis of intramedullary tumor. After 2 months of postoperative antifungal treatment, the patient's clinical condition had markedly improved. Cryptococcoma should be considered when an enhancing lesion of the spinal cord is found on MR imaging, even in apparently immunocompetent patients. A careful lumbar puncture for cerebrospinal fluid analysis to diagnose cryptococcosis of the central nervous system should be made promptly, as early treatment is associated with a good prognosis.

Cryptococcosis↗
PubMed2000

Gastrointestinal metastasis in hepatocellular carcinoma: radiological and endoscopic studies of 11 cases.

BACKGROUND: From October 1990 to January 1999, 11 of 2237 hepatoma patients at our hospital had gastrointestinal tract metastasis. We describe the radiological and endoscopic features, clinical course and prognoses of those patients. METHODS: All patients were male. Six patients were hepatitis B carriers, and cirrhosis was noted in eight patients on admission. We reviewed all available radiological, endoscopic and pathological features. RESULTS: The commonest clinical presentation was frank gastrointestinal bleeding. Histological proof of gastrointestinal involvement was seen in six patients. Endoscopic features included ulcerative tumours mimicking advanced gastric carcinoma (43%) and submucosal tumours (29%). The sites of organ involvement were stomach (five), duodenum (two), colon (three) and duodenum and colon (one). Direct invasion by a contiguous neoplasm was the major route of gastrointestinal tract metastasis. Portal vein thrombosis may be the key point of haematogenous spread to other sites. CONCLUSIONS: The prognosis in these patients was extremely poor. Almost all patients died within 5 months if no further aggressive management was performed. Surgical intervention may be the optimal choice for palliative treatment of HCC with gastrointestinal tract involvement.

Aged↗
PubMed2000

Small hepatocellular carcinoma: safety and efficacy of single high-dose percutaneous acetic acid injection for treatment.

PURPOSE: To evaluate the safety and efficacy of single high-dose percutaneous acetic acid injection (PAI) for treatment of small (<3-cm-diameter) hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Eighteen patients with HCC (22 nodules; diameter range, 1.5-3.0 cm) underwent single PAI. With ultrasonographic or computed tomographic (CT) guidance, 4-11 mL of 50% acetic acid was slowly injected into the center of the nodule through a skinny multiple-side-hole needle. Follow-up was performed with helical contrast material-enhanced CT. Complications of high-dose PAI were recorded. RESULTS: Seventeen nodules showed no local recurrence (follow-up, 6-29 months) after single PAI. At a mean follow-up of 15.6 months, mean tumor diameter was 2.1 cm and mean injected volume was 6.4 mL. Four nodules showed residual tumor (mean tumor diameter, 2.6 cm; mean injected volume, 5.8 mL). The mean ratio of injected to estimated volume of acetic acid was 1.21 in cases of successful single PAI and 0.72 in cases of local recurrence (P < .001). One patient with preexistent right portal venous thrombosis died of hepatic failure 37 days after PAI. Other complications included severe pain (11%), high fever (4%), and segmental wedge infarction (4%). CONCLUSION: Single high-dose PAI is safe and effective for treatment of small HCC.

Acetic Acid↗
PubMed2000

Carpal tunnel syndrome caused by tophaceous gout: CT and MR imaging features in 20 patients.

OBJECTIVE: The objective of this study is to describe the CT and MR imaging findings of gouty tophi in the wrist and present this entity as a cause of carpal tunnel syndrome. MATERIALS AND METHODS: Retrospective review of the CT (n = 18) and MR imaging (n = 20) studies of the wrist in patients with a documented diagnosis of gout who presented with gout-related carpal tunnel syndrome was performed; images of 24 wrists were collected over a 5-year period. Patient population included 20 men, who ranged in age from 35 to 76 years. All images were reviewed by two musculoskeletal radiologists who reached a consensus opinion. Surgical correlation was available in 12 patients. RESULTS: Tophi were found in the floor of the carpal tunnel (n = 18), carpal bones (n = 17), radiocarpal joint (n = 17), and extensor tendons or tendon sheaths (n = 16) of the wrist. All tophi showed similar signal characteristics (from low to intermediate signal intensity on T1-weighted images with heterogeneous signal intensity on T2-weighted images) with the exception of tophi in the floor of the carpal tunnel (low signal intensity on T2-weighted images). Varying degrees of calcification were noted on CT and MR imaging studies. Gadolinium-enhanced MR studies showed heterogeneous enhancement. CONCLUSION: Gouty tophi should be entertained as a cause of carpal tunnel syndrome in the appropriate patient population. Familiarity with this entity and its imaging characteristics may prove helpful in diagnosis and preoperative planning.

Adult↗
PubMed2000

Unusual signs for dural arteriovenous fistulas with diffuse basal ganglia and cerebral calcification.

We present a case of multiple dural arteriovenous fistulas (AVFs) in a 60-year-old man with the chief complaint of worsening headache, altered mental status and progressively unsteady gait over the course of one year. Computerized tomography revealed diffuse, symmetric calcification in the bilateral basal ganglia and bilateral periventricular and subcortical white matter. Magnetic resonance imaging revealed multiple, enhanced, punctate and linear vessels. These images were due to reflux into the parenchymal veins in the dural AVF of the superior sagittal sinus within the basal ganglia and deep white matter of both cerebral hemispheres. Cerebral angiography disclosed multiple dural AVFs. The exact mechanism of basal ganglia and subcortical calcification is proposed to be an arterial steal phenomenon or persistent venous congestion, with calcification occurring in a chronic hypoperfused state or with dystrophic changes in the walls of congested veins.

Arteriovenous Fistula↗
PubMed2000

Recurrent gastrointestinal bleeding and high output cardiac failure caused by hereditary hemorrhagic telangiectasia.

Hereditary hemorrhagic telangiectasia, commonly known as Osler-Weber-Rendu disease, is a systemic autosomal dominant inherited disorder, that occurs in Caucasian populations. We report the case of a 56-year-old housewife who was admitted to the gastrointestinal and cardiovascular ward because she had suffered from recurrent gastrointestinal bleeding and heart failure from 1994 to 1997. Panendoscopy showed vascular ectasia scattered over the tongue, larynx, esophagus, and posterior wall of the gastric body. Colonoscopy showed clusters of telangiectasia over the cecum and ascending colon. Arteriovenous malformations (AVMs) were found in the liver and lungs on computerized tomography. Recurrent gastrointestinal bleeding was controlled by estrogen treatment during the follow-up period. In July 1997, the patient was readmitted to our cardiovascular section due to aggravated dyspnea, orthopnea and bilateral lower leg edema. Cardiac catheterization showed a large fistula from the left pulmonary artery to the left atrium and left ventricle, pulmonary arterial pressure of 37/13 mmHg and cardiac output of 9.61/minute. Other studies excluded the possibility of sepsis, and high-output cardiac failure was suspected. The patient was discharged in a stable condition and scheduled for AVM embolization management. Unfortunately, she died of a suspected heart attack at home two weeks following discharge.

Cardiac Output↗
PubMed1999

Intra-articular gouty tophi of the knee: CT and MR imaging in 12 patients.

OBJECTIVE: To define the imaging characteristics of intra-articular tophi of the knee. DESIGN AND PATIENTS: Twelve patients with intra-articular tophi in the knee were studied with routine MR imaging, gadolinium (Gd)-enhanced MR imaging, and CT over a 4-year period. There were 11 men and one woman, 25-82 years of age (mean age 48 years). Four patients did not have a documented history of gout at the time of the MR examination. The diagnosis of intra-articular tophi was provided by arthroscopy and histological examination (5 patients), by microscopic study of joint fluid (5 patients), or by characteristic clinical, laboratory and imaging findings (2 patients). RESULTS: In 15 MR examinations the tophi were located purely intra-articularly in 10 knees. In the remaining five MR studies, periarticular soft tissues or bone, or both, were involved. All the intra-articular tophi manifested low to intermediate signal intensity on both T1- and T2-weighted images. All five Gd-enhanced MR examinations demonstrated a heterogeneous peripheral enhancement. All 10 CT scans showed varying degrees of stippled calcifications within the tophi. The nature of the calcifications was confirmed on histological examination in three patients. CONCLUSION: Presenting clinical manifestations of gout may relate to intra-articular tophaceous deposits. Such deposits present as masses on MR images with low to intermediate signal intensity on both T1- and T2-weighted images and a characteristic enhancement pattern following intravenous Gd administration. These features relate primarily to internal calcifications, which are most evident on CT images. MR evaluation (including Gd administration) supplemented, in some cases, with CT scanning allows accurate diagnosis of intra-articular tophaceous deposits.

Adult↗
PubMed1999

Central nervous pathway for acupuncture stimulation: localization of processing with functional MR imaging of the brain--preliminary experience.

PURPOSE: To characterize the central nervous system (CNS) pathway for acupuncture stimulation in the human brain by using functional magnetic resonance (MR) imaging. MATERIALS AND METHODS: Functional MR imaging of the whole brain was performed in two groups of nine healthy subjects during four stimulation paradigms: real acupuncture at acupoints ST.36 (on the leg) and LI.4 (on the hand) and control stimulations (minimal acupuncture and superficial pricking on the leg). Stimulations were performed in semirandomized, balanced order nested within two experiments. Psychophysical responses (pain, De-Qi effect [characteristic acupuncture effect of needle-manipulation sensation], anxiety, and unpleasantness) and autonomic responses were assessed. Talairach coordinates-transformed imaging data were averaged for a group analysis. RESULTS: Acupuncture at LI.4 and ST.36 resulted in significantly higher scores for De-Qi and in substantial bradycardia. Acupuncture at both acupoints resulted in activation of the hypothalamus and nucleus accumbens and deactivation of the rostral part of the anterior cingulate cortex, amygdala formation, and hippocampal complex; control stimulations did not result in such activations and deactivations. CONCLUSION: Functional MR imaging can demonstrate the CNS pathway for acupuncture stimulation. Acupuncture at ST.36 and LI.4 activates structures of descending antinociceptive pathway and deactivates multiple limbic areas subserving pain association. These findings may shed light on the CNS mechanism of acupuncture analgesia and form a basis for future investigations of endogenous pain modulation circuits in the human brain.

Acupuncture Analgesia↗
PubMed1999

Small functional adrenal cortical adenoma: treatment with CT-guided percutaneous acetic acid injection--report of three cases.

Two patients with Conn syndrome and one patient with Cushing syndrome underwent computed tomography (CT)-guided tumor ablation with a total of 5-11 mL of 50% acetic acid injected into their adrenal nodule (1.3-3.3 cm in diameter). No major complications were encountered during or after the procedure. All patients were symptom free with normal laboratory test results for at least 1-year follow-up. CT images showed complete cystic change with tumor size regression. Our preliminary results suggest that percutaneous acetic acid injection is a safe and effective alternative for treatment of small functional adrenal cortical adenoma.

Acetic Acid↗
PubMed1999

Intracranial acute arterial ischemia of the anterior circulation: evaluation with three-dimensional time-of-flight magnetic resonance angiography.

BACKGROUND: Stroke has been the second most common cause of death, after cancer, in Taiwan since 1983. The cost of stroke to society in terms of morbidity, mortality and economics is profound. Heightened interest in the early diagnosis and treatment of acute stroke challenges neuroimagers to optimize available modalities and to develop new techniques for the evaluation of cerebrovascular disease. The aim of this study was to investigate the effectiveness of magnetic resonance angiography (MRA) in conjunction with spin-echo imaging in patients with acute brain infarction of the anterior circulation. METHODS: Magnetic resonance imaging and three-dimensional Fourier transformed time-of-flight MRA studies, performed on 50 patients within one week after the onset of cerebral ischemia, were retrospectively reviewed and correlated with clinical records. Five of the 50 MRAs were considered nondiagnostic and excluded because of poor patient cooperation. RESULTS: In 41 of the 45 cases, the area of infarct corresponding to the clinical deficit at the time of study was identified on T2-weighted spin-echo images. Arterial occlusions or severe stenoses that corresponded to ischemic manifestations were identified with MRA in 37 of the 45 patients. A focal discontinuity with decreased arterial caliber corresponded to stenosis and nonvisualization of distal branches represented arterial occlusion. MRA provided information for 23 cases not obtained from the MR images. CONCLUSIONS: Vascular lesions demonstrated on intracranial MRA show a high correlation with infarct distribution. MRA, which provides information adjunctive to conventional MR imaging in a majority of cases, is concluded to be an important component of the complete evaluation of brain infarction.

Acute Disease↗
PubMed1999

Imaging diagnosis of insufficiency fracture of the sacrum.

BACKGROUND: Insufficiency fracture of the sacrum has been recognized as a major cause of lower back pain, especially in elderly osteoporotic patients with or without underlying malignancy and/or prior pelvic radiotherapy. Its diagnosis cannot be readily made from its nonspecific clinical features. Consequently some cases may be mistaken for bone metastases, causing patients to receive inappropriate diagnostic measures and management. Recognition of the spectrum of imaging features is the basis of correct diagnosis and treatment. METHODS: The imaging studies of 14 cases (12 women and 2 men; age range, 60-84 years; mean age, 70 years) of sacral insufficiency fracture were reviewed retrospectively. These included 14 radiographs, six bone scintigraphs, eight computerized tomography (CT) scans and 12 magnetic resonance (MR) imaging studies. Six patients had a history of malignancy. Diagnosis was made by characteristic imaging findings, and clinical and radiographic follow-up for one to 3.5 years. RESULTS: Five cases of sacral insufficiency fracture were suspected based on radiographic findings of fracture lines (2 cases) and focal sclerosis (3 cases). Seven cases were diagnosed by CT findings of linear fractures (7 cases) and focal sclerosis (2 cases). Nine MR examinations demonstrated characteristic vertical bands of marrow edema. A hypointense fracture line was identified in eight cases. The remaining two MR imaging studies disclosed nonspecific focal marrow edema. An early case, which appeared normal on CT scan, showed marrow edema on MR imaging. The positive and diagnostic rates were both 36% for plain radiographs, 88% for CT scans, and 100% and 83%, respectively, for MR images. CONCLUSIONS: Plain radiographs are often unrewarding. Although MR imaging is the most sensitive tool, fracture lines are best demonstrated and diagnosed using CT. Due to the better diagnostic rate, popularity and cost effectiveness, CT is recommended as the definitive modality for confirming diagnosis of insufficiency fracture of the sacrum.

Aged↗
PubMed1999

Recurrent inverted papilloma: diagnosis with pharmacokinetic dynamic gadolinium-enhanced MR imaging.

BACKGROUND AND PURPOSE: Dynamic gadolinium-enhanced MR imaging has been used successfully to identify post-treatment recurrence or postoperative changes in rectal and cervical carcinoma. Our purpose was to evaluate the usefulness of dynamic gadolinium-enhanced MR imaging for distinguishing recurrent inverted papilloma (IP) from postoperative changes. METHODS: Fifteen patients with 20 pathologically proved lesions (recurrent IP, 12; fibrosis or granulation tissue, eight) were enrolled in the study. Three observers, blinded to pathologic results, independently evaluated conventional MR images, including T1-weighted (unenhanced and postcontrast), proton-density-weighted, and T2-weighted spin-echo images. Results then were determined by consensus. Dynamic images were obtained using fast spin-echo sequences at 5, 30, 60, 90, 120, 150, 180, and 300 seconds after the injection of gadolinium-diethylene-triamine penta-acetic acid. Time-signal intensity curves of suspected lesions were analyzed by a pharmacokinetic model. The calculated amplitude and tissue distribution time were used to characterize tissue, and their values were displayed as a color-coded overlay. RESULTS: T2-weighted images yielded a sensitivity of 67%, a specificity of 75%, and an accuracy of 70% in the diagnosis of recurrent IP. Contrast-enhanced T1-weighted images yielded a sensitivity of 75%, a specificity of 50%, and an accuracy of 65%. Pharmacokinetic analysis showed that recurrent IP had faster (distribution time, 41 versus 88 seconds) and higher (amplitude, 2.4 versus 1.2 arbitrary units) enhancement than did fibrosis or granulation tissue. A cut-off of 65 seconds for distribution time and 1.6 units for amplitude yielded a sensitivity of 100% and a specificity of 100% for diagnosing recurrent IP. CONCLUSION: Dynamic MR imaging can differentiate accurately recurrent IP from postoperative changes and seems to be a valuable diagnostic tool.

Adult↗
PubMed1999

Detection and assessment of circle of Willis aneurysms in acute subarachnoid hemorrhage with three-dimensional computed tomographic angiography: correlation with digital substraction angiography findings.

In this retrospective study, we examined the usefulness of computed tomographic angiography (CTA) for the detection and assessment of circle of Willis aneurysms in patients with acute nontraumatic subarachnoid hemorrhage (SAH), using selective digital substraction angiography (DSA) as the gold standard. Thirty-five patients who presented with acute, nontraumatic SAH, diagnosed on the basis of unenhanced computed tomography or lumbar puncture findings or both, underwent both CTA and DSA. The CTA images were interpreted for the presence, location, size, and shape of the aneurysm, presence of a neck, and relationship of the aneurysm to adjacent arterial branches. The CTA and DSA images were then compared, with the latter images serving as the gold standard. DSA revealed 37 aneurysms in 32 patients and ruled out intracranial aneurysms in the remaining three. The sensitivity and specificity of CTA for aneurysm detection were 97% and 100%, respectively. The size of the smallest aneurysm shown was 4 mm, and the largest aneurysm was 21 mm. The size and lobularity of the aneurysms estimated from CTA images corresponded well with those estimated from DSA images. In addition, CTA provided a three-dimensional representation of the aneurysmal lesion, which was considered useful for surgical planning. Our results confirm the accuracy of CTA in comparison with DSA. Because of its reliability, minimal invasiveness, and rapidity, CTA may become the technique of choice for neuroradiologic work-up of SAH patients. DSA then would be used to diagnose intracranial aneurysms only in selected, questionable cases.

Acute Disease↗