Clinical characteristic and management of haemophilia patients in Malaysia: A single centre experience

INTRODUCTION

Haemophilia is one of the commonest inherited bleeding disorders which may lead to long term disabilities if not treated properly. Our aim of study is to understand the clinical characteristic, treatment and complications of adult haemophilia patients in our centre.

MATERIALS AND METHODS

A retrospective cross-sectional review of all adult haemophilia A (HA) or haemophilia B (HB) patients who received treatment in Hospital Pulau Pinang from January 2021 to December 2022 was conducted. Data was retrieved from patients' medical records.

RESULTS

A total of 75 haemophilia patients (64 HA and 11 HB) were included in this study with median age of 37 years (range 19 70). 42 of them had severe haemophilia (50% of HA, 91% of HB). All HB and 93.8% of severe HA patients were on prophylaxis. Six severe and one mild HA patients developed inhibitor with four of them currently on non-factor prophylaxis. 24 patients (32%) had prior hepatitis C infection and all of them have been successfully treated. The mean annual bleeding rate for severe haemophilia patients were 1.77 (SD ±3.6). Target joints were observed in 9.3% of patients with ankle joint (71.4%) being the most affected joint. More than one quarter (26.7%) of our patients have comorbidities with majority of them having hypertension (17/20), followed by diabetes mellitus (5/20) and ischemic heart disease (5/20).

CONCLUSION

Our study showed that a significant number of adult patients with haemophilia have comorbidities. Apart from optimising factor replacement therapy, future planning should include improvement in screening, risk modification and prevention of cardiovascular disease.

High prevalence of central hypothyroidism among patients with transfusion dependent thalassemia in Hospital Pulau Pinang: A cross sectional study

INTRODUCTION

Thalassemia is the most common heritable haematological disorder in Malaysia. Hypothyroidism is one of the complications of the transfusion dependent thalassemia (TDT) patients as a result of iron overload.

MATERIALS AND METHODS

All registered TDT patients attending Haematology day care, Hospital Pulau Pinang from January 2019 to January 2020 were included in the study. Hypothyroidism was defined according to TSH and FT4, or based on the history of treatment for diagnosed hypothyroidism.

RESULTS

There were 51 TDT patients, with 24 (47%) males and 27 (53%) females. Most of the patients were Malays (27, 53%) followed with Chinese (23, 45%) and Indonesian (1, 2%). Beta thalassemia major and HbE beta thalassaemia accounted for 35 (68.8%) and 14 (27.5%) TDT patients respectively, while two (3.9%) were HbH Constant Spring. Eleven (21.6%) had hypothyroidism; of which seven (63.6%) had central hypothyroidism, three (27.3%) had subclinical hypothyroidism, the remaining one (9.1%) had primary hypothyroidism. Three (27.3%) had concomitant hypogonadism, one (9.1%) had hypocortisolism and another (9.1%) had both diabetes mellitus and hypogonadism. There was no statistical relationship between the prevalence of hypothyroidism and age, serum ferritin, splenectomy history and iron chelation therapy.

CONCLUSION

High prevalence of central hypothyroidism is reported. Measurement of both TSH and FT4 is recommended as initial screening for thyroid dysfunction among patient with TDT.

Prevalence of endocrine complications in transfusion dependent thalassemia in Hospital Pulau Pinang: A pilot study

INTRODUCTION

Frequent blood transfusions results in iron overload and lead to multiple endocrine complications. In spite of improvements in iron chelation therapy, a significant number of transfusion dependent thalassaemia (TDT) patients still develop endocrine complications. The aim of this study is to evaluate the prevalence of various endocrine complications in our adult TDT patients and to study the correlation with serum ferritin and liver iron concentration (LIC).

METHODS

A retrospective review of all TDT patients treated in Haematology Unit, Hospital Pulau Pinang (HPP) was conducted.

RESULTS

Of the 45 adult TDT patients, 22 were males and 23 were females with mean age of 28.8±6.9 years old. Majority of TDT in HPP were beta thalassemia major (71.1%), followed by E-Beta thalassemia (24.4%) and HbH-Constant Spring (4.4%). Frequency of transfusion was 3-4 weekly. 40.0% of adult TDT suffered from at least one endocrine complication. Among the adult TDT patients with endocrine complication, 50% have one endocrinopathy, 38.9% with two types of endocrinopathies and 11.1% of them have three or more types of endocrinopathies. Hypogonadism (22.2%) was the commonest endocrine complication, followed by osteoporosis (20%), hypothyroidism (13.3%), diabetes mellitus (6.7%) and hypocortisolism (4.4%). Patients with endocrine complications were significantly older. Mean serum ferritin level and LIC was higher among patients with endocrine complications but both were not statistically significant.

CONCLUSION

Endocrinopathy is still prevalent in 40% of adult TDT patients. This leads to higher health-care resource utilization, cost and significant morbidities among patients with TDT. Therefore, regular monitoring and early detection with intensification of chelation therapy is essential.

Endocrine complications in transfusion dependent thalassaemia in Penang Hospital

Frequent blood transfusions can lead to iron overload which may result in several endocrine complications especially in the absence of adequate chelation therapy. The objectives of this study are to determine the prevalence of endocrine complications in transfusion dependent thalassaemia patients and the correlation of endocrine complications with the degree of iron chelation. This retrospective study looked at cases of adult patients with transfusion dependent thalassaemia treated in the Haematology Unit, Penang Hospital. Of the 25 transfusion dependent thalassaemia patients, there were 10 male and 15 female patients respectively with almost equal number of Malay and Chinese patients (13 and 12 patients respectively). Short stature was seen in 36.0% of our patients. In our cohort, 12 patients had delayed puberty (male 70.0% and female 33.3%). Prevalence of osteoporosis was 36.0%. Hypogonadism was noted in 40.0% of males and 46.7% of females. 53.4% of the female population had menstrual abnormalities with prevalence of primary and secondary amenorrhoea at 26.7% each. The prevalence of other endocrinopathies was much lower: 8.0% had diabetes mellitus and only one patient had hypocortisolism. Iron chelation appeared insufficient in our study population. The high frequency of endocrine complications noted in our study supports the rationale for regular follow-up of transfusion dependent thalassaemic patients to ensure early detection and timely treatment of associated complications.

Clinical positron emission tomography imaging--current applications

Positron emission tomography (PET) is an established imaging technique based on the use of short-lived radiotracers. The unique value of PET lies in the ability of various radiochemical compounds to serve as tracers for measuring specific metabolic processes in the body. This enables detection of the early biochemical anomalies that precede the structural changes seen on other imaging techniques. For decades, PET had remained essentially a research tool in academic institutions. However, in recent years, it has emerged as a vital clinical tool, particularly for cancer diagnosis and management. In this era of evidence-based medicine, the clinical applications of PET imaging have been subjected to intense evaluation, and its roles in oncology, neurology and cardiology have dominated nuclear medicine research and scientific publications in the past 5 to 8 years. This review article summarises the present status of the major clinical indications for PET scanning. The field is rapidly evolving and, with the recent advent of hybrid PET-CT scanners, new data continue to emerge, refining these clinical applications. Another important area of ongoing research is the development of new radio-labelled compounds for PET imaging.

Intermediate probability lung scans (IPLS): retrospective review of 82 cases

OBJECTIVE

In the light of a reported 30-40% prevalence of pulmonary embolism (PE) in intermediate probability lung scans (IPLS) based on results of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study, we examined the frequency of documented PE in 82 patients with IPLS, the management strategy employed in these patients with regards to additional imaging (e.g. further evaluation with venous sonography or spiral computed tomographic angiography (CTA)), anticoagulation therapy, and subsequent follow-up outcomes.

METHOD

Retrospective review of the medical records of 82 patients with intermediate probability ventilation-perfusion (V/Q) lung scans from January 1998 to July 1999.

RESULTS

14.1% of V/Q scans were reported as having an intermediate probability of PE. 72% of IPLS were subject to further evaluation with venous Doppler ultrasound and/or CTA, and 39% of these patients had evidence of thrombo-embolic disease. All patients with imaging evidence of thromboembolic disease were started on anticoagulation therapy. In addition, 19 patients were treated based on clinical judgement. Amongst the 35 patients who were not treated, 17 (49%) were based on clinical findings without further imaging. There was no mortality on follow-up of 28 cases of untreated IPLS.

CONCLUSION

The majority of IPLS will have further imaging, out of which over one-third will have thrombo-embolic disease. Approximately half of IPLS cases will receive anticoagulation therapy. No mortality or PE was found on follow-up of patients who were not treated.

Orbital inflammation in a patient with extrascleral spread of choroidal malignant melanoma

An elderly woman presented with fever, dehydration, orbital inflammation, total external and internal ophthalmoplegia and blindness, resembling the clinical appearance at presentation of severe orbital inflammatory disease or mucormycosis. Orbital computed tomography scanning demonstrated a retrobulbar orbital mass. Subsequent B-scan ultrasound examination confirmed the orbital mass but also demonstrated a mass within the eye. At lateral orbitotomy, extrascleral spread of an entirely necrotic intraocular melanoma was demonstrated. As computed tomography scanning may not be able to delineate an entirely necrotic intraocular malignant melanoma, B-scan ultrasonography should be considered in patients with orbital inflammation, especially in the presence of a retrobulbar mass.

Noise and speckle reduction in synthetic aperture radar imagery by nonparametric Wiener filtering

We present a Wiener filter that is especially suitable for speckle and noise reduction in multilook synthetic aperture radar (SAR) imagery. The proposed filter is nonparametric, not being based on parametrized analytical models of signal statistics. Instead, the Wiener-Hopf equation is expressed entirely in terms of observed signal statistics, with no reference to the possibly unobservable pure signal and noise. This Wiener filter is simple in concept and implementation, exactly minimum mean-square error, and directly applicable to signal-dependent and multiplicative noise. We demonstrate the filtering of a genuine two-look SAR image and show how a nonnegatively constrained version of the filter substantially reduces ringing.

Evaluation of technetium-99m ciprofloxacin (Infecton) in the imaging of infection

INTRODUCTION

The aim of this study was to evaluate the usefulness of technetium-99m (Tc-99m) ciprofloxacin in imaging inflammation/infection. The ciprofloxacin for labelling, as a kit, was obtained from St Bartholomew's Hospital in London.

MATERIALS AND METHODS

Patients were injected intravenously with Tc-99m ciprofloxacin and imaging was done at 10 minutes, 4 hours and 24 hours if necessary. Tomographic images (SPECT) were obtained in a few patients. Ninety-six patients were studied using Tc-99m ciprofloxacin. Forty-eight patients had bone scans and 22 had Tc-99m IgG scans. Eight patients were imaged using Tc-99m HMPAO labelled white blood cell, and bacteriological culture results were available in 24 patients. Organisms cultured included Acinetobacter baumanii, Streptococcus, Staphylococcus aureus, Pseudomonas, Klebsiella, Blastococidia, Methicillin-resistant S. aureus, Salmonella and Candida.

RESULTS

Findings were evaluated against microbiology, alternative imaging modalities and clinical outcome. There were 47 true positives, 33 true negatives, 5 false positives and 11 false negatives, giving a sensitivity of 81% and specificity of 87%. The positive and negative predictive values were 90% and 75%, respectively. There were no side effects and the scan was particularly useful in the evaluation of painful joint prosthesis to exclude infection. Repeat studies on 8 patients given antibiotics over a long period were very useful in deciding on termination of the antibiotic treatment.

Technetium-99m sestamibi for the assessment of myocardial salvage following reperfusion therapy in acute myocardial infarction

INTRODUCTION

Reperfusion therapy with either thrombolysis or angioplasty has been shown to be beneficial in acute myocardial infarction. Tc-99m sestamibi is a myocardial tracer that can be used to assess myocardial salvage because of its property of very limited redistribution.

MATERIALS AND METHODS

To assess the feasibility of this technique locally, Tc-99m sestamibi was injected before and after reperfusion therapy with angioplasty (n = 11) or streptokinase (n = 18) in 29 patients with acute myocardial infarction (anterior = 25, inferior = 4). Single-photon emission computed tomography (SPECT) was performed within 4 hours of reperfusion and repeated 5 to 7 days later.

RESULTS

Initial perfusion defect size ranged from 6% to 78% (mean 36.3 +/- 18.7%), and final defect size from 0% to 50% of the left ventricle (mean 23.7 +/- 14.8%, P < 0.001). Patients with proximal left anterior descending artery (LAD) lesions had larger defects compared to those with mid LAD lesions (mean defect size 52% for pLAD versus 28% for mLAD, P < 0.013). However, there were wide variations in initial defect size (myocardium at risk) for a given infarct-related artery location. The mean decrease in defect size was 12% in the 28 patients with patent arteries compared to only 2% in the patient with an occluded artery (47% to 45%). There was no significant difference in amount of salvage between patients who had thrombolysis (mean 13%, P = 0.0003) and patients who had percutaneous transluminal coronary angioplasty (PTCA) (mean 12%, P = 0.005).

CONCLUSIONS

Assessment of myocardial salvage is feasible using Tc-99m sestamibi SPECT imaging. It allows for quantitation of myocardium at risk and the amount of myocardial salvage, which is not possible by angiography alone.

Making the diagnosis of biliary atresia using the triangular cord sign and gallbladder length

BACKGROUND

To evaluate the accuracy and utility of the triangular cord sign and gallbladder length in diagnosing biliary atresia by sonography.

MATERIALS AND METHODS

Sixty fasted infants with cholestatic jaundice aged 2-12 weeks were examined sonographically using a 5-10 MHz linear array transducer, focusing on the triangular cord sign (as described by Choi et al. [1]), the gallbladder, and ducts. The triangular cord is defined as a triangular or tubular echogenic density seen immediately cranial to the portal vein bifurcation; it represents the fibrotic remnant of the obliterated cord in biliary atresia. The findings were blinded to blood chemistry, (99 m)Tc-DISIDA hepatobiliary scintigraphy, and liver biopsy. Diagnosis of biliary atresia was confirmed at surgery and histology. Non-biliary atresia infants resolved medically. Comparative charges of the various investigations was made.

RESULTS

++ Twelve infants had biliary atresia, and ten demonstrated a definite triangular cord. The two false-negatives had small or nonvisualized gallbladders. No false-positives were recorded. Gallbladder length ranged from 0-1.45 cm with a mean of 0. 52 cm in biliary atresia compared to a mean of 2.39 cm in nonbiliary atresia infants. (99 m)Tc-DISIDA hepatobiliary scintigraphy showed no excretion (false-positive) in 23 % of nonbiliary atresia cases. Scintigraphy and liver biopsy charges were 2 and 6 times that of sonography, respectively.

CONCLUSION

The triangular cord sign and gallbladder length together are noninvasive, inexpensive, and very useful markers for biliary atresia.

Five micro-curie urea breath test for the diagnosis of Helicobacter pylori infection: evaluation in a South-East Asian population

BACKGROUND

Helicobacter pylori is an important pathogen responsible for significant morbidity and mortality. Its prevalence varies widely in different geographical locations and is especially high in parts of Asia.

METHODS

A double-blind study was carried out to evaluate the use of the 5 microCi (185 KBq) [14C]-urea breath test ([14C]-UBT) in a South-East Asian population by validating its diagnostic accuracy against histology and the CLO test.

RESULTS

The sensitivity and specificity of the [14C]-UBT was 100% when compared against the CLO test. When histology was used as the 'gold standard', the sensitivity and specificity were 100% and 97.2%, respectively. There was no overlap or indeterminate values between positive and negative results on the [14C]-UBT.

CONCLUSIONS

Among South-East Asian populations where the prevalence of H. pylori infection is high, the high sensitivity of the 5 microCi [14C]-UBT makes it a very important test in the detection of H. pylori.

Epidemiology of aplastic anaemia in the state of Sabah, Malaysia

Aplastic anaemia is a rare disease which is more prevalent in the Far East. In Malaysia, it appears to be unusually common in the state of Sabah. A retrospective analysis of all cases of aplastic anaemia diagnosed between January 1993 and March 1996 was undertaken. The criteria of the International Aplastic Anaemia and Agranulocytosis Study (IAAAS) was used. In this 39 month period, 31 cases were confirmed by marrow trephine biopsy to be aplastic anaemia. The male-to-female ratio was 3.4. Median age of diagnosis was 23 years. There were 24 patients (77%) who were from the Kadazan-Dusun ethnic group, which forms 18% of the population of Sabah. The incidence of aplastic anaemia in Sabah appears to be higher than that reported elsewhere in the Far East, at 4.8 per million population per year. Peak incidence is in the elderly group at 8.6 per million followed by a second peak in young people aged 15 to 24 (7.9 per million). The aplastic anaemia to total acute leukaemia ratio is 0.37. The marked male preponderance and apparent susceptibility of the Kadazan-Dusun people are also notable. A further prospective study to address the true incidence of aplastic anaemia and possible aetiologic factors accounting for these observations is necessary.

Radionuclide imaging in primary hyperparathyroidism using 99mTc sestamibi--four case reports

Radionuclide imaging using the 99mTc sestamibi either singly or as a subtraction technique with pertechnetate is a recent and reliable method in localising parathyroid adenomas prior to surgery. This is of use in pre-operative planning, as well as in failed first neck exploration. Four local patients with primary hyperparathyroidism whose parathyroid adenomas were localised by this scintigraphy are presented. The value and limitations of this imaging modality are discussed.

Technetium-99m (Tc-99m) diphosphono-propanedicarboxylic acid bone tracer uptake and Tc-99m sestamibi distribution in cardiac amyloidosis--a case report

It has long been recognised that significant bone tracer localisation in the myocardium is a good indicator for amyloid involvement of the heart in the clinical context of systemic amyloidosis. In this case report, although myocardial tissue diagnosis of amyloidosis was not made, the massive myocardial uptake of bone tracer strongly suggested the presence of amyloid infiltration in the heart, and this finding eventually led to the histological diagnosis of familial amyloid polyneuropathy by skin and sural nerve biopsy. Interesting findings were noted in the single photon emission computerised tomography (SPECT) studies of the myocardium with Technetium-99m diphosphono-propanedicarboxylic acid bone agent and Technetium-99m sestamibi myocardial perfusion agent. Such findings suggest that there is a lack of correlation between the intensity of myocardial uptake of bone tracer and viability of the myocardium, and that amyloid will not deposit in infarcted myocardial tissue.

Myocardial perfusion imaging with technetium-99m sestamibi SPECT in the evaluation of coronary artery disease

Technetium-99m hexakis-2-methoxy-isobutyl-isonitrile (99mTc sestamibi) has been used for myocardial perfusion imaging in the evaluation of coronary artery disease (CAD) since 1990. The experience of its use in an Asian population with and without previous myocardial infarction (MI), diabetes mellitus (DM), hypertension (HPT) and collateral circulation (COL) is reported. One hundred and thirty-nine patients who underwent treadmill exercise testing with 99mTc sestamibi single photon emission computed tomography (SPECT) and coronary angiogram were studied. The overall sensitivity for the detection of CAD was 91.0% and specificity was 64.7%. For patient without previous myocardial infarction, the sensitivity was 83.8% and specificity was 83.3%. Patients with COL had a higher sensitivity while those with HPT had a lower specificity. Sensitivity was higher in patients with multi-vessel disease (MVD) than single vessel disease (SVD). The overall detection for individual artery stenosis was 74.1% with a specificity of 73.1%. Amongst the three major coronary arteries, sensitivity was highest for the right coronary artery and specificity was highest for the left circumflex artery. Specificity was higher in patients without MI or COL. We found that the agreement between 99mTc sestamibi SPECT and coronary angiogram for the extent of CAD was only 52.5%. The concordance rate was higher for patients with MVD than SVD. It is concluded that 99mTc sestamibi SPECT is a sensitive and specific test for the detection of CAD and localization of disease to individual coronary arteries in our patients with some differences in the subgroups. Agreement between coronary angiogram and 99mTc sestamibi for the extent of coronary artery disease was also satisfactory.

Radionuclide detection of dialysate leakage in patients on continuous ambulatory peritoneal dialysis

While continuous ambulatory peritoneal dialysis (CAPD) offers several advantages over haemodialysis in patients with end-stage renal disease, several complications have been recognised. The intraperitoneal instillation of dialysate increases intra-abdominal pressure and consequently predisposes to leaks and herniations through defects in the abdominal wall. This can lead to disruption of CAPD therapy. Peritoneal scintigraphy with Tc99m colloid has been used to identify such leaks of dialysate. This report analyses the clinical role of peritoneal scintigraphy in patients on the CAPD programme in the Singapore General Hospital. The results of 25 scans performed over a two-and-a-half year period were correlated with clinical and surgical findings. The clinical presentations of suspected dialysate leakage were varied, but can be broadly classified into three subsets for this analysis: (A) swellings confined to the inguinal and genital region, (B) peri-catheter, umbilical and incisional swellings, and (C) diffuse pattern of swellings in the abdominal wall, pelvic and genital region. In group A, the scan proved to be clearly helpful, correctly identifying 10/10 inguinal hernias, all of which resolved after herniorrhaphy. In group B, the scan correctly identified 7/9 leaks and hernias in the ventral abdominal wall. There was one false negative scan in a patient with a peri-catheter leak, and an equivocal result in another with fluid leakage in the lower anterior abdominal wall. In group C, which presented the greatest difficulty in clinical diagnosis, 2/3 cases were correctly diagnosed by scintigraphy. An equivocal result was seen in a patient who had had multiple operations for recurrent incisional hernias.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of technetium-99m sestamibi in localisation of thyroid cancer metastases

Technetium-99m sestamibi (MIBI) is a routinely used myocardial perfusion imaging agent. We have studied groups of patients with differentiated thyroid carcinoma, in order to evaluate the usefulness of this agent in localising regional neck and nodal disease and metastases. There are three groups of patients. Group 1 consisted of patients with known nodal disease or metastases (22 patients) and with raised serum thyroglobulin levels (Tg). Group 2 comprised patients with normal I-131 scans and normal Tg levels (nine patients). Non-thyroid malignancies (six patients) comprised an additional group 3. In group 1, the MIBI scan showed 47 sites of metastases, while the I-131 scan revealed 49 sites. The MIBI scan was positive in two patients where the I-131 scan was negative, while in two other patients, the MIBI study was negative whereas the I-131 scan was positive. In group 2, 6/9 patients had no disease, 2/9 had thyroid remnants, and 1/9 had a fresh primary lung tumour, unrelated to the earlier thyroid cancer. All of them had normal MIBI scans. In group 3, two patients with lung cancer and two with breast cancer and metastases had normal MIBI scans. A further two patients with nasopharyngeal cancer (NPC) had mildly increased MIBI localisation in neck nodes and bone metastases. In summary, Tc-99m sestamibi appears to be as good as I-131 in search for thyroid carcinoma metastatic spread, especially nodal disease and this tracer does not localise well in the primary or metastases of other cancers.(ABSTRACT TRUNCATED AT 250 WORDS)

99Tcm-polyclonal IgG and 99Tcm nanocolloid scans in orthopaedics: a comparison with conventional bone scan

The bone scan is sensitive in detection of active bone/joint lesions. A normal bone scan virtually excludes the presence of an inflammatory process with high precision, but the poor specificity of bone scans is well known. In recent years, various new agents including 99Tcm-hexamethylpropylene amine oxime (HMPAO)-labelled white blood cells, nanocolloid, polyclonal IgG, anti-granulocyte antibody, 111In-labelled IgG, leucocytes, chemotactic peptides etc. have been widely evaluated in inflammatory imaging, especially in the orthopaedic context. This study was undertaken to compare the usefulness of 99Tcm-nanocolloid and 99Tcm-polyclonal IgG in the detection of focal bone/joint inflammation. Twenty-seven patients with a common presentation of bone/joint pain resulting from various pathologies were included in the study. A total of 47 lesions were imaged. The overall sensitivity and specificity of both nanocolloid scan and IgG scan were identical with 95% sensitivity and 100% specificity, in detecting inflammatory foci. However, specificity dropped to 18% with nanocolloid scans and 16% with IgG scans when an attempt was made to distinguish noninfective from infective inflammatory processes; thus neither type of scan permits differentiation between septic and nonseptic inflammatory processes with sufficient accuracy. As both nanocolloid and IgG scans are equally sensitive and specific in detecting inflammation, the choice of type of scan will depend on cost, imaging time and availability of the radiopharmaceutical.

Reverse redistribution in thallium-201 stress tests in coronary artery disease--a brief report

Reverse redistribution (RR) is the apparent worsening of a stress-induced defect or the appearance of a new defect in the myocardium in the delayed thallium images. This has been linked to the presence of coronary artery disease. In this article, we examine the incidence of this phenomenon in our local population, and its pathophysiological significance.

Bone scintigraphy in nasopharyngeal carcinoma

One hundred and forty-three patients (Group 1) with histologically proven nasopharyngeal-carcinoma (NPC) had bone scintigraphy with 99Tcm methylenediphosphonate (MDP) or dihydroxypropanediphosphonate (DPD) within 2 months of the initial diagnosis. A further 162 patients (Group 2) had bone scans during the course of follow-up if there were symptoms of bone pain or evidence of metastases at other sites. Twenty-three per cent (33/143) of the newly diagnosed NPC patients (Group 1) had evidence of bone metastases. Of these 143 patients, 101 were T0-T2, 16 were T3 and 25 were T4. Thirty-six patients had no neck nodes (NO), 44 were N1, 25 N2 and 38 N3. Of the 162 patients in Group 2, 96 (59%) had a positive bone scan. The commonest sites for bony metastases from NPC were the spine, ribs, pelvis and lower limbs in order of frequency. There is a highly significant association with the nodal stage but no association with the UICC T staging which is not adequate in nasopharyngeal carcinoma. In our part of the world, bone metastases from NPC are a common cause of an abnormal bone scan.

Nuclear cardiology in the detection of coronary artery disease--an overview of its role in the Singapore General Hospital

Nuclear cardiology at the Singapore General Hospital (SGH) had a humble beginning in 1983 when it was carried out by the joint staff of the departments of cardiology and nuclear medicine. At the onset the bulk of the scans were blood pool studies. In 1984, qualitative tomographic myocardial perfusion studies replaced the less accurate planar scans and this was carried out on a routine basis. Its superiority to conventional exercise electrocardiography in the detection, management and prognostication of coronary artery disease (CAD) has since been validated locally. We have since progressed to the fields of research involving pharmacological stress testing with intravenous dipyridamole and use of technetium-based isonitrile as an alternative to the conventional myocardial perfusion agent, thallous chloride. Our results mirror those from other research centres. On this encouraging note we are looking into newer areas such as the role of diastolic function for early detection of cardiac disease. In under a decade we are in a position to provide scintigraphic service expected of an established nuclear cardiac laboratory. This article provides an overview of our work in the management of CAD.

99Tcm-(tin) colloid scans in the evaluation of renal transplant rejection

Technetium-99m-(tin) colloid uptake in renal transplants was quantified to evaluate rejection. A dynamic acquisition following i.v. injection of 110 MBq of this radiopharmaceutical enabled quantification of 15 to 20 min transplant uptake (PU), in terms of percentage of an injected dose after allowing for attenuation in the patient. An uptake ratio (UR) i.e. the ratio of 15 to 20 min uptake over the 0 to 5 min uptake was also derived. Normal values were obtained in 20 stable functioning transplants (normal PU less than or equal to 1%, normal UR less than or equal to 0.7). In 66 patients, PU and UR were compared with clinical, biochemical, histological and radiological, evidence of rejection. A sensitivity of 70% and specificity of 85% was obtained for this 99Tcm-(tin) colloid study in the diagnosis of renal transplant rejection.

Upper airway dilating forces during wakefulness and sleep in dogs

We measured the pressure within an isolated segment of the upper airway in three dogs during wakefulness (W), slow-wave sleep (SWS) and rapid-eye-movement (REM) sleep. Measurements were taken from a segment of the upper airway between the nares and midtrachea while the dog breathed through a tracheostoma. These pressure changes represented the sum of respiratory-related forces generated by all muscles of the upper airway. The mean base-line level of upper airway pressure (Pua) was -0.5 +/- 0.03 cmH2O during W, increased by a mean of 2.1 +/- 0.2 cmH2O during SWS, and was variable during REM sleep. The mean inspiratory-related phasic change in Pua was -1.2 +/- 0.1 cmH2O during wakefulness. During SWS, this phasic change in Pua decreased significantly to a mean of -0.9 +/- 0.1 cmH2O (P less than 0.05). During REM sleep, the phasic activity was extremely variable with periods in which there were no fluctuations in Pua and others with high swings in Pua. These data indicate that in dogs the sum of forces which dilate the upper airway during W decreases during SWS and REM sleep. The consistent coupling between inspiratory drive and upper airway dilatation during wakefulness persists in SWS, but is frequently uncoupled during REM sleep.

99mTechnetium(V) dimercaptosuccinic acid (99mTc(v) DMSA) as a tumour seeking agent in nasopharyngeal carcinoma

We prepared 99mTechnetium(V) DMSA (pentavalent form) as an imaging agent for eighteen patients with proven nasopharyngeal carcinoma. The head, neck, chest and abdomen were scanned. The nasopharyngeal tumour showed tracer accumulation in only 5 out of the 18 patients (28%). The study indicates that 99mTechnetium(V) DMSA is not a useful radiopharmaceutical for visualising nasopharyngeal tumours although it may have other useful properties.

Case report of a parathyroid adenoma demonstrated by dual tracer (T1-201 and Tc-99m) subtraction scan

It is generally agreed that the Technetium-Thallium Subtraction Scan is a reliable method for locating abnormal parathyroid glands in patients with clinical and biochemical evidence of parathyroid hyperactivity. This report illustrates the value of scintigraphy in diagnosis and in the subsequent surgical management of a patient with primary hyperparathyroidism.

Radionuclide bone imaging in patients with low back pain presenting to the orthopaedic surgeon

This study looks retrospectively at 113 patients with low back pain referred by orthopaedic surgeons for bone scanning. 79 scans (70%) were reported normal and 34 scans (30%) abnormal. 61 out of the 79 patients with normal scans were diagnosed and managed as "chronic back strain". Negative bone scans were also encountered in 3 patients with degenerative disease, 3 with prolapsed intervertebral disc and one with spondylolysis. In those patients with positive scans, a varied range of diagnoses was encountered, the main ones being bone metastases, previous trauma, osteomyelitis and degenerative disease. The scan was shown to be helpful in deciding on the presence or absence of pathology, and in identifying the sites of involvement, but not the nature of the disease. A higher likelihood of positivity is seen in the more elderly patients as well as those below 20 years of age. In interpreting the scan, the clinical context is important e.g. a history of trauma, previous surgery or of malignant disease. The bone scan may be normal in disc prolapse and in degenerative disease of the spine.

Tomographic thallium-201 stress scintigraphy in the evaluation of coronary artery disease

57 patients with chest pain, had tomographic thallium-201 stress scintigraphy (TTSS), and coronary angiography within three months of the TTSS. The exercise images were compared with delayed images obtained at 3 hours post-exercise. The sensitivity and specificity of locating individual coronary artery disease was 88% and 100% for disease of left anterior descending artery (LAD), 89% and 83% for right coronary artery disease (RCA), and 24% and 96% for left circumflex artery (LCX) disease. Other than for LCX disease, our results compare favourably with other reports. The overall accuracies are 91%, 86% and 60% for LAD, RCA and LCX disease respectively.

Radionuclide measurement of liquid and solid gastric emptying in normal subjects in Singapore

Scintigraphic methods for liquid and solid gastric emptying were utilised to study normal patterns in 21 volunteers. Of these, 19 had solid emptying studies and 14 had liquid emptying studies. The liquid study lasted 1/2 hour, while the solid study was for 1 hour. The gastric emptying half-time (T 1/2), as well as percentage retention at 15 minutes (liquids), and at 60 minutes (for solids) were noted. The time-activity curves were also corrected for tissue attenuation. Results indicated normal average liquid emptying T 1/2 to be 14.2 minutes, while that for solids was 116 minutes.

Hepatobiliary scintigraphy in the diagnosis of biliary atresia--a Singapore experience

In recent years, 99mTechnetium IDA hepatobiliary scintigraphy has been widely accepted as a highly sensitive and fairly accurate test in the diagnosis of biliary atresia and evaluation of neonatal jaundice. Over a period of 4 years from 1982 to 1986, a total of 110 paediatric patients had undergone 99mTechnetium IDA hepatobiliary scans in our department for prolonged neonatal jaundice. Their scans were reviewed to evaluate the role of this nuclear imaging technique in the diagnosis of biliary atresia. There were 43 true positive and 49 true negative scans. No false negative scan was encountered in our study. Hence the sensitivity was 100%. However, out of the 110 scans, there was misdiagnosis of biliary atresia in 18 cases. This gave a specificity of 73% with an accuracy of 84%. From this study we concluded that 99mTechnetium IDA imaging is a highly sensitive test in the screening of biliary atresia. However, its specificity is possibly limited by the short half life of the radioisotope 99mtechnetium in delayed 24 hr imaging and we feel that this could be improved by using slightly higher doses than what we are presently using.

Nuclear medicine--an overview

A radioactive isotope behaves chemically and biologically like its non-radioactive counterpart. The application of this principle to medical diagnosis has evolved into a whole specialty called nuclear medicine. The development of the rectilinear scanner and gamma camera has extended the study of molecular pathways into an exciting imaging modality while developments in radiopharmaceuticals have made radionuclide imaging of many organ systems widely available. The most significant improvements have occurred in bone, hepatobiliary and cardiac imaging. Today, however, nuclear medicine is evolving into a more dynamic study of physiological processes in the body and how these processes may be affected by disease and medical treatment. Emission tomography with a new generation of both gamma and positron emitters will be integral part of nuclear medicine in the future. The challenge to develop radio-labelled antibodies for immunotherapy and immunodetection remains while many of the older techniques like radioimmunoassay, and even the simple colloid liver scan, will continue to contribute significantly to health care.