Procedure guidelines for radionuclide myocardial perfusion imaging.
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Clinical Protocols↗
Biomedical subjects
A Notghi
Publications and source records attributed to A Notghi.
Relationship between myocardial counts and patient weight: adjusting the injected activity in myocardial perfusion scans.
It is generally accepted that the quality of myocardial images deteriorates with increasing patient weight. This is attributed to a reduction of counts detected from the myocardium. In this paper we have looked at the count reduction in obese patients and suggest a workable algorithm to increase the injected activity to compensate for this loss of count. In this prospective study, 64 consecutive patients with normal myocardial images were selected to include a weight range of 50-120 kg. The height, weight and gender of patients were noted. Each patient had two studies (total of 128 studies), one at rest and one following stress with adenosine and 20-40 W bicycle exercise. Total myocardial counts were calculated from the back-projected views. The total myocardial counts per MBq of the injected activity were calculated. There was no significant difference in the injected activity and the size of the heart (pixel length of heart) between stress and rest, or gender of the patient. The normalized myocardial counts were not different between men and women, but the counts were slightly, although not significantly, higher ( P=NS) with adenosine and exercise (mean of 243 x 10(3) counts) compared to rest images (229 x 10(3) counts). There was a significant progressive loss of counts in patients with increasing weight, body mass index or body surface area ( P<0.001). There was no significant difference in the changes in counts with weight between male and female, or rest and stress studies. The combined data from all the studies were used to calculate the correlation coefficient and the slope of the line for reduction of cardiac counts with a patient's weight, body mass index, and body surface area. The best correlation was with patient weight ( r=0.58, P<0.001). This was used to calculate the increase in injection activity with increasing weight to maintain the same average counts as achieved in a 70 kg patient with a 400 MBq injection. We suggest that the injection activity should increase from 100% for a 70 kg patient to 140% for 110 kg, 200% for 140 kg, and 250% for a 150 kg patient.
Body Mass Index↗
Procedure guidelines for radionuclide myocardial perfusion imaging.
Radionuclide myocardial perfusion imaging (MPI) is an established and non-invasive imaging technique with diagnostic and prognostic efficacy in the investigation of coronary artery disease. It is the only widely available test for assessing myocardial perfusion directly but there are variations in the way it is performed in different centres. Harmonization of practice, at least at a national level, is therefore essential, and clinical governance now makes it mandatory for practice to be based upon evidence whenever possible [ 1]. This is best achieved by expert analysis of the evidence and to this end the British Nuclear Cardiology Society (BNCS) in association with the British Cardiac Society (BCS) and the British Nuclear Medicine Society (BNMS) have developed procedure guidelines for tomographic myocardial perfusion imaging. A systematic literature search was performed and every effort was made to conform with the AGREE recommendations [ 2]. All recommendations are therefore based on either evidence from clinical studies, previous published guidelines or expert consensus of the writing and advisory groups. The guidelines cover the clinical indications of MPI, the methods used for stress testing, the radiopharmaceuticals and the injected activities and also issues related to acquisition, processing and interpretation of images. They do not cover the benefits or drawbacks of the technique in specific circumstances; neither do they address its cost effectiveness in clinical diagnosis and management nor its potential impact on clinical outcomes. The guidelines aim to assist medical practitioners and other health care professionals in recommending, performing, interpreting and reporting single photon emission computed tomography (SPECT) of myocardial perfusion.
Coronary Artery Disease↗
Adsorption of radiopharmaceuticals to syringes leads to lower administered activity than intended.
In this study we examined the delivered activity of radiopharmaceuticals injected into patients and the various factors which lead to incomplete delivery. Four commonly used 99Tcm radiopharmaceuticals were included, namely pertechnetate, methylene diphosphonate (MDP), macro-aggregated albumin (MAA) and tetrofosmin. There was no appreciable residual activity after injection of pertechnetate and MDP other than that due to the dead space in syringes (0.06 ml, 4% of measured activity). However, there was considerable residual activity following an MAA injection. This was particularly dependent on the radiopharmaceutical residence time in the syringe prior to injection. If MAA was pre-dispensed there was up to 80% of activity remaining in the syringe following injection. We have shown that this activity is not bound and can be decreased by agitating the syringe prior to the injection. For tetrofosmin, the activity remaining in the syringe was shown to be mostly due to adsorption of the tetrofosmin onto the plastic syringe (up to 30% of the activity); in particular, onto the rubber plunger. The amount of binding probably depends on the formulation of the rubber plunger and the plastic barrel, which varies between manufacturers. Of the three commonly used syringe brands (Becton-Dickinson, Sherwood, and Braun syringes) the Braun syringes were shown to have the least binding (6%) and would be most suitable for tetrofosmin injection. We recommend the use of Braun syringes for tetrofosmin. We also recommend that pre-dispensed MAA injections should be gently agitated before injection into the patient. No special precautions are necessary for pertechnetate or MDP injections.
Adsorption↗
Estimation of ascitic fluid volume using 99Tcm labelled macroaggregated albumin.
We have assessed the usefulness of a radionuclide dilution method for estimation of ascitic fluid volume. 99Tc(m) macroaggregated albumin (10 MBq) was injected into the peritoneal fluid. Multiple samples were taken using a trocath peritoneal dialysis catheter over a 4-h period. Blood samples were taken at the same time and a 4-h urine collection was made during the study. At 4 h a controlled drainage of ascitic fluid, followed by suction drainage, was used and a total drained volume measured. For comparison, peritoneal volumes were measured from the radioactivity of peritoneal fluid activity samples using dilution techniques. The estimated peritoneal fluid volume using the radionuclide method was consistently higher than the drained volume. This was attributed to either a lack of uniform distribution of the activity in the peritoneal cavity by 4 h or early breakdown and absorption of activity from the peritoneal cavity. In two patients it was not possible to measure a volume due to poor distribution of the radionuclide in the peritoneal fluid. We found that in our group of patients the radionuclide dilution is of little value in estimating the peritoneal fluid volume.
Adult↗
Can reduced imaging times be used for scintimammography?
A reduction in acquisition times from 10 to 5 min for scintimammography does not reduce the diagnostic value of the study when imaging for detection of breast lesions. The test showed an overall sensitivity of 96%, specificity of 100% and accuracy of 98% for breast lesions visualized on both 5 and 10 min acquisitions. Even if lymph node detection is the primary concern of the study, longer scan times do not increase the sensitivity of the test (40% on both 5 and 10 min). Scintimammography is poor at detecting lymph nodes (sensitivity 40%, specificity 69-82%) and is not useful for assessing lymph node involvement. A reduction in imaging times appeared to be consistent on both camera systems tested, which have very different display outputs. This would indicate that other departments may be able to reduce times on their systems without affecting the quality of the study. The detection of breast lesions was also consistent between reporters.
Breast↗
The influence of major histocompatibility complex class II genes and T-cell Vbeta repertoire on response to immunization with HBsAg.
Nonresponsiveness to HBsAg vaccination is observed in 5-10% of vaccine recipients and is possibly caused by a defect in the T helper cell compartment. The immune response to HBsAg is influenced by genes of the major histocompatibility complex. We have investigated MHC class I and class II antigens in 53 adult responders and 73 nonresponders. Results obtained in this first study were tested in a second study with 56 responders and 62 nonresponders from an infant vaccination trial. In addition, the peripheral Vbeta-chain T-cell receptor repertoire was investigated using monoclonal antibodies and flow-cytometry in 26 adult responders and 38 nonresponders. As previously reported, nonresponsiveness to HBsAg vaccination was associated with DRB1*3 and DRB1*7. In addition, DRB1*13 was significantly increased among vaccine responders (35.2% vs 5.4%;p < 0.0001) suggesting an immune response promoting effect for this allele whereas the closely related allele DRB1*14 was associated with nonresponse in the infant study. There was no evidence for a hole in the T cell receptor Vbeta repertoire. In conclusion, in agreement with results obtained in mice there appears to be a hierarchy of DRB1* genes in the HBsAg immune response. The possible differential association of DRB1*13 and DRB1*14 may allow the identification of differences between responsiveness and nonresponsiveness to a few amino acid differences in the beta1-domain of the class II heterodimer.
Adult↗
Counting the cost of patients who do not attend nuclear medicine departments.
The mean rate of non-attendance at this hospital is 16%, with the Nuclear Medicine Department averaging 4%. Although only a small percentage, increasing demand for nuclear medicine studies has led to a need for greater efficiency to reduce financial losses. From April 1995 to March 1996, 104 patients did not attend over a range of 16 studies. We examined the types of study, patients and costs. The costs of wasted staff time, camera time and radiopharmaceutical ranged from pound sterling 24 (99Tc(m) thyroid) to pound sterling 470 (75Se cholesterol adrenal). This results in a loss equivalent to pound sterling 7258 over the year. There was no significant difference in non-attendance rates between different types of procedure, source and type of referral, or in the three age groups: children, working and retired population. Finally, we looked at cultural origins, segregating the groups into Asian and European origins based on surname. A significantly higher proportion of patients of Asian origin did not attend. This study has shown that it may be of benefit to target specific groups and tests. For example, at City Hospital, perhaps we should concentrate on our Asian community to ensure they understand fully what the study involves. It would also be worthwhile targeting the more expensive nuclear medicine studies.
Adolescent↗
Nausea, bloating and constipation.
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Constipation↗
MHC class II genes influence the susceptibility to chronic active hepatitis C.
BACKGROUND/AIMS: Chronic hepatitis C develops in more than 70% of hepatitis C virus infected subjects. Viral factors influence the disease course, but little is known about the importance of host factors. METHODS: Frequencies of major histocompatibility complex (MHC) class I and class II antigens were analyzed in two groups of patients with chronic hepatitis C virus infection and in control subjects. MHC class I typing was done by standard microlymphocytotoxicity assays. DRB1 and DQA1 genotyping was done by PCR based typing methods. RESULTS: DRB1*0301 was found in 26 of 75 patients with chronic hepatitis C virus infection (34.7%) and in 12 of 101 control subjects (11.9%) (relative risk 3.9; p < 0.001). Homozygosity for this allele appeared to confer a stronger risk. In contrast, DRB1*1301 was detected in three subjects with persistent infection (4.0%) compared to 21 control subjects (20.8%) (relative risk 0.2; p < 0.008). This allele was linked with DQA1*0103, which was found in 10 patients (13.3%) compared to 34 control subjects (33.7%) (relative risk 0.31; p < 0.003). An even stronger protective effect was provided by the presence of DRB1*1301 and DQA1*0103 (relative risk 0.08; p < 0.005). These findings were confirmed in a second group of chronic hepatitis C virus infected patients. CONCLUSIONS: The MHC class II allele DRB1*0301 appears to predispose to progression to chronic active hepatitis C, whereas the class II alleles DRB1*1301 and DQA1*0103 appear to provide protection against chronic active infection with hepatitis C virus.
Alleles↗
HLA-DRB1*1301 and *1302 protect against chronic hepatitis B.
BACKGROUND/AIMS: The outcome of acute hepatitis B infection may be influenced by host factors like the major histocompatibility complex (MHC). We have investigated MHC class I and class II antigens in patients with chronic hepatitis B compared to a healthy control population. To confirm the findings of this first study we performed a second study in a group of subjects who had spontaneously recovered from acute hepatitis B infection. METHODS: Frequencies of MHC class I and class II antigens were analyzed in patients with chronic hepatitis B virus infection and in control subjects. MHC class I typing was done by standard microlymphocytotoxicity assays. DRB1 and DQA1 genotypes were determined by polymerase chain reaction based typing methods. RESULTS: In the first study the class II allele HLA-DRB1*1301-02 was found in 4 of 70 subjects with chronic hepatitis B virus infection (5.7%) compared to 27 of 101 healthy controls (26.7%, relative risk 0.17; p=0.001; p(corr)=0.025). This protective effect of the DRB1*1301-02 allele was confirmed in the second study. Eight of 24 patients (33.3%) who cleared hepatitis B virus spontaneously were positive for DRB1*1301-02 (relative risk of developing chronic infection compared to chronic hepatitis B subjects 0.12; p=0.004). Subtyping confirmed that 1301 and 1302 were both decreased in frequency in patients with chronic hepatitis B. CONCLUSIONS: The MHC class II allele DRB1* 1301-02 is associated with protection from chronic hepatitis B in Caucasian patients.
Adult↗
Are MIBI/tetrofosmin heart studies a potential radiation hazard to technologists?
The number of nuclear medicine studies is increasing and they are becoming more complex and time-consuming. In particular, this is true of myocardial perfusion investigations. We use a one-day protocol for these studies, utilizing 99Tc(m)-MIBI or 99Tc(m)-tetrofosmin with tomographic rest images (250 MBq) acquired in the morning and exercise images (750 MBq) approximately 4 h later after pharmacological stress. Imaging technologists are concerned about continual exposure to 1000 MBq 99Tc(m) per study. Radiation doses were measured during rest (1.0 microSv, n = 18), exercise (2.5 microSv, n = 18) and stress administration (2.0 microSv, n = 16), giving a total dose of 5.5 microSv per combined cardiac study. We have previously shown that the average dose per radionuclide study (excluding myocardial perfusion studies) is 1.5 microSv. Although 5.5 microSv is higher, a technologist is highly unlikely to exceed current dose limits. New EC legislation, however, is expected to reduce these limits, which may lead to more classified workers. Pregnant technologists should avoid, if possible, combined cardiac studies, especially if performing other nuclear medicine duties.
Adenosine↗
Out-of-hours weekend scintigraphy: assessing/predicting the need.
We have assessed the potential impact of a regular half-day session on Saturday only, or Sunday only, and compared this with a whole weekend on-call service for lung scans. We predicted the effect of these services using the data gathered over 2 years (1992-94), looking at the results of lung scans and admission and discharge of patients. The on-call service in all three cases would be justified if resources from the savings on patient discharge and bed availability could be earmarked for the nuclear medicine service. The cost of introducing such an on-call service for the department would be Pounds 3000 per year per session at the weekend and up to Pounds 10,000 per year for a full weekend on-call service. The total cost to the hospital would be negligible.
Costs and Cost Analysis↗
Imaging of anorectal function.
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Anal Canal↗
Long-term follow up to determine the prognostic value of imaging after urinary tract infections. Part 1: Reflux.
In 3646 children with at least one confirmed urinary tract infection the prevalence of vesicoureteric reflux at presentation was correlated with progressive renal damage during follow up of not less than two and up to 16 years. Reflux was not demonstrated either at presentation or at any subsequent time in almost one half of the children who suffered progressive renal damage and was not a risk factor for progressive renal damage in boys under 1 year. It was an important risk factor in boys over 1 year and in girls of any age. The risk of progressive renal damage in children in whom micturating cystourethrography (MCU) did not reveal vesicoureteric reflux was substantially greater than in those who indirect isotope voiding study (IVS) did not show reflux. The risk of deterioration for those in whom reflux was demonstrated was similar for both techniques. This discrepancy indicates an appreciably higher false negative rate for the MCU than the IVS. Dilatation of the renal pelvis detected by ultrasound was associated with a significantly increased risk of progressive damage only when associated with reflux, but most children with progressive damage did not have a dilated collecting system at presentation.
Adolescent↗
Long-term follow up to determine the prognostic value of imaging after urinary tract infections. Part 2: Scarring.
Long term follow up of children with urinary tract infections, in whom imaging investigations were performed at presentation, has been used to identify features that distinguish those at greatest risk of progressive renal damage. No single investigation at presentation was able to predict subsequent deterioration but, by employing a combination of imaging investigations, it was possible to separate groups with high or low probability of progressive damage. In the low risk group the incidence of progressive damage was 0.2% (95% confidence interval (CI) 0 to 1.3%). The combination of both scarring and reflux at presentation, or one only of these but accompanied by subsequent documented urinary tract infection, was associated with a 17-fold (95% CI 2.5 to 118) increase in the relative risk of progressive renal damage compared with children without these features. The recommended combination of investigations at presentation for girls of any age and boys over 1 year is ultrasound and dimercaptosuccinic acid (DMSA) scintigraphy in all, to detect both scarring and significant structural abnormalities, renography in children with dilatation of any part of the urinary tract on ultrasound, to distinguish dilatation from obstruction, and an isotope voiding study in all who have acquired bladder control. This gives the best separation between those at high and those at low risk of progressive damage with least radiation dose and lowest rate of instrumentation. Micturating cystourethrography (MCU) should be restricted to girls who have not acquired bladder control, unless there is reason to suspect a significant structural abnormality such as urethral valves. A single non-febrile urinary tract infection that responds promptly to treatment is not a justification for performing MCU in boys under 1 year or in children of any age with bladder control. No case can be made for any abbreviated schedule of investigation. These risk factors should be taken into account when designing follow up protocols.
Adolescent↗
Reporting simplified colonic transit studies using radionuclides: clinician friendly reports.
This study describes a graphic presentation of the results of a simplified segmental colonic transit model. This study requires three sets of images on three consecutive days after intake of indium-111 resin capsule at each time point. The per cent of ingested activity is calculated in each region of the colon and in the faeces. The program uses standard PC compatible graphic package, CorelDRAW (Corel Corporation). The report for the patients' notes consists of three schematic diagrams of colon with regions identified and a pot representing the faecal activity. The per cent of administered activity in each region and pot is both printed and represented by shades of grey (white representing 0% and black 100% activity), for each region and the pot. The distribution of activity is clearly seen at each time point and the report is presented on single A4 size sheet of paper. Using a simplified colonic study protocol it is possible to produce clinician friendly reports on a single sheet of paper.
Colon↗
Scintigraphic measurement of ileocaecal transit in irritable bowel syndrome and chronic idiopathic constipation.
This study investigated the hypothesis that some features of functional gastrointestinal disorders may be associated with abnormalities of ileocaecal transit by measuring ileocaecal transit using a scintigraphic technique in 43 patients with chronic constipation, 20 patients with irritable bowel syndrome (IBS), and 18 control subjects. Subjects ingested enteric coated capsules, which delivered 111-indium radionuclide to the distal ileum. Gammacamera images were acquired at hourly intervals until caecal filling was complete. Ileocaecal transit was defined as the time between peak scintigraphic activity in the terminal ileum and peak activity in the caecum. The mean (SD) ileocaecal transit of 103 (50) minutes in patients with IBS was significantly faster than that in control subjects (mean (SD) ileocaecal transit 174 (78) minutes, p < 0.002). There were no significant differences in ileocaecal transit between patients with chronic idiopathic constipation and the control subjects, or between patients with constipation predominant and diarrhoea predominant IBS. This study developed a practical scintigraphic method of measuring ileocaecal transit. The rapid ileocaecal transit in both the constipation and diarrhoea predominant forms of IBS suggests that bloating may not after all result from delayed ileal emptying.
Adult↗