EANM/ESC procedural guidelines for myocardial perfusion imaging in nuclear cardiology.

The European procedural guidelines for radionuclide imaging of myocardial perfusion and viability are presented in 13 sections covering patient information, radiopharmaceuticals, injected activities and dosimetry, stress tests, imaging protocols and acquisition, quality control and reconstruction methods, gated studies and attenuation-scatter compensation, data analysis, reports and image display, and positron emission tomography. If the specific recommendations given could not be based on evidence from original, scientific studies, we tried to express this state-of-art. The guidelines are designed to assist in the practice of performing, interpreting and reporting myocardial perfusion SPET. The guidelines do not discuss clinical indications, benefits or drawbacks of radionuclide myocardial imaging compared to non-nuclear techniques, nor do they cover cost benefit or cost effectiveness.

The absent kidney in 99Tcm-MAG3 renogram: a dramatic reversible consequence of contrast nephrotoxicity superimposed on renal obstruction.

99Tcm-mercaptoacetyltriglycine (MAG3) renogram is a robust imaging technique used to delineate upper urinary tract obstruction. The changes observed on the renogram are often reversible on relief of obstruction. We present two cases illustrating the extreme consequence of contrast nephrotoxicity on pre-existing obstructed kidneys. In one case, this led to severe impairment of perfusion and uptake observed on 99Tcm-MAG3 renogram and in the second case virtual non-visualization of the obstructed kidney. Subsequent treatment of obstruction, led to dramatic improvement in renal function. It is important for clinicians, nuclear medicine physicians and radiologists to be aware of the potential of contrast nephrotoxicity in obstructed kidneys.

Myocardial perfusion scintigraphy: the evidence.

This review summarises the evidence for the role of myocardial perfusion scintigraphy (MPS) in patients with known or suspected coronary artery disease. It is the product of a consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society and is endorsed by the Royal College of Physicians of London and the Royal College of Radiologists. It was used to inform the UK National Institute of Clinical Excellence in their appraisal of MPS in patients with chest pain and myocardial infarction. MPS is a well-established, non-invasive imaging technique with a large body of evidence to support its effectiveness in the diagnosis and management of angina and myocardial infarction. It is more accurate than the exercise ECG in detecting myocardial ischaemia and it is the single most powerful technique for predicting future coronary events. The high diagnostic accuracy of MPS allows reliable risk stratification and guides the selection of patients for further interventions, such as revascularisation. This in turn allows more appropriate utilisation of resources, with the potential for both improved clinical outcomes and greater cost-effectiveness. Evidence from modelling and observational studies supports the enhanced cost-effectiveness associated with MPS use. In patients presenting with stable or acute chest pain, strategies of investigation involving MPS are more cost-effective than those not using the technique. MPS also has particular advantages over alternative techniques in the management of a number of patient subgroups, including women, the elderly and those with diabetes, and its use will have a favourable impact on cost-effectiveness in these groups. MPS is already an integral part of many clinical guidelines for the investigation and management of angina and myocardial infarction. However, the technique is underutilised in the UK, as judged by the inappropriately long waiting times and by comparison with the numbers of revascularisations and coronary angiograms performed. Furthermore, MPS activity levels in this country fall far short of those in comparable European countries, with about half as many scans being undertaken per year. Currently, the number of MPS studies performed annually in the UK is 1,200/million population/year. We estimate the real need to be 4,000/million/year. The current average waiting time is 20 weeks and we recommend that clinically appropriate upper limits of waiting time are 6 weeks for routine studies and 1 week for urgent studies.

Positron emission and computed X-ray tomography: a coming together.

We describe the introduction of positron emission tomography/computed tomography (PET/CT) to the investigation of patients with cancer. The first such unit in the UK and its mode of operation is discussed and initial applications shown. Five hundred and thirty-five patients have been scanned with 2-[18F]fluoro-2-deoxy-D-glucose from mid-January 2002 to the end of August 2002. From this initial experience a clear view of the impact of this technology is emerging. It can now be stated that (1) PET/CT does speed up the throughput of patient studies by at least 25% and hence adds to the comfort of patients scanned; and (2) PET/CT leads to greater accuracy in the interpretation of data. In view of the routine availability of high quality PET and CT fused maps a significant development in radiotherapy planning is on the horizon. We discuss our experience at present and point to further developments in the near future.

Nuclear medicine and radionuclide imaging: a survey of recruitment issues in the United Kingdom.

This wide ranging survey has highlighted difficulties in recruiting trained and committed individuals into nuclear medicine and radionuclide radiology. Several key factors have been recognised that reduce the attractiveness of the training. Recommendations include the rotation of medical senior house officers through nuclear medicine, reconsideration of dual accreditation in nuclear medicine and medicine, an increase in the number of consultant posts in nuclear medicine, parity of remuneration for nuclear medicine trainees and finally, an appropriate sessional provision for those providing radionuclide radiology services.

A new approach to pre-treatment assessment of the N0 neck in oral squamous cell carcinoma: the role of sentinel node biopsy and positron emission tomography.

OBJECTIVES: Pre-operative staging of the clinically N(0) neck in patients with oral squamous cell carcinoma is hindered by the relatively high false negative/positive rates of conventional imaging techniques. The aim of this study is to evaluate the utility of (18)F-fluoro-deoxy-glucose (FDG) positron emission tomography (PET) and sentinel lymph node (SLN) imaging and biopsy to determine the true disease status of the loco-regional lymphatics. METHODS: Nineteen patients with biopsy proven disease without palpable or radiological evidence of neck metastases underwent pre-operative (18)F-FDG PET and SLN imaging. All patients underwent whole-body FDG PET and a single view of the head and neck. SLN technique was performed using four peri-tumoural injections of (99m)Tc labeled albumin colloid each of 10 MBq. Dynamic and static imaging followed in the antero-posterior and lateral projections. At operation 1 ml of 2.5% Patent Blue Dye and a hand held gamma probe (Neoprobe 1500) were used in combination to identify and remove the SLN. Surgery then continued along conventional lines including a neck dissection. Histology of the resultant specimen was correlated with that of the SLN and pre-operative imaging. RESULTS: In all patients SLN harvesting was feasible. In 15/19 patients the SLN(s) and the residual neck dissection were -ve for tumour. In 3/19 patients the SLN(s) were +ve for tumour as were other neck nodes. In 1/19 patients the SLN was -ve but another single tumour +ve node was identified in the neck. This patient occurred early in our series with a SLN close to the primary tumour. (18)F-FDG PET failed to identify nodal disease in all four patients with histologically proven lymph node metastases. The size of these nodes ranged from 12 mm x 10 mm x 3 mm to 25 mm x 15 mm x 10 mm. CONCLUSION: SLN imaging and biopsy with probe and Patent Blue Dye guided harvest is feasible in patients with oral squamous cell carcinoma and can predict cervical nodal status. (18)F-FDG PET may be less useful.

Fluorodeoxyglucose positron emission tomography in clinical oncology: the referrer's perspective.

From January 2000 to April 2002 a prospective audit based on a questionnaire was carried out concerning the attitudes and viewpoints of clinicians referring patients to fluorodeoxyglucose positron emission tomography (FDG PET) scanning. A standard and structured audit form was posted to each referring doctor with the formal clinical report issued by the nuclear medicine consultant. Three hundred and thirty evaluable forms were analysed, a return rate of approximately 22%, from a total of 1500 PET patients studied during this period. FDG PET scanning was deemed by the referring physician to have altered the staging of cancer patients in 39% of all cases. Twenty-five per cent of patients were upstaged with FDG PET and 14% of patients downstaged. Patient management was changed in 39% of cases whilst a change in treatment occurred in 10% of cases. The reported FDG PET study was judged as being helpful in over 75% of all cases. These data further support evidence of the increasing role of FDG studies in the investigation of patients with cancer.

Influence of arm positioning on tomographic thallium-201 myocardial perfusion imaging and the effect of attenuation correction.

Lateral attenuation in single-photon emission tomography (SPET) myocardial perfusion imaging (MPI) has been attributed to the left arm if it is held by the patient's side during data acquisition. As a result MPI data are conventionally acquired with the arms held above the head. The aims of this study were to determine the effect of imaging arms down on reconstructed tomographic images depicting regional myocardial thallium-201 distribution and to assess whether attenuation-corrected (AC) myocardial perfusion images acquired arms down could replace uncorrected (NC) images acquired arms up for routine clinical service. Twenty-eight patients referred for routine MPI underwent sequential 180 degrees emission/transmission imaging for attenuation correction using an L-shaped dual-headed gamma camera (GE Optima) fitted with two gadolinium-153 scanning line sources. Delay data were acquired twice: once supine with the arms up and then supine with the arms down. Detector radius of rotation (ROR) for arms up and arms-down studies was recorded. For each data set, count density was measured in 17 segments of a polar plot and segmental uptake expressed relative to study maximum. Oblique images were assessed qualitatively by two observers blinded to study type for tracer distribution and overall quality. Transmission maps were assessed for truncation. Mean detector ROR was 190 mm for arms-up studies and 232 mm for arms-down studies (P<0.05). Population mean segmental relative uptake values for NC arms-up studies were higher than for NC arms-down studies, with the greatest difference seen anterolaterally. Nevertheless, the majority (24/28) of oblique NC arms-up and NC arms-down images appeared similar and only four (14%) NC arms-down studies showed additional areas of reduced count density (one anterior and three lateral). Corresponding AC arms-down studies showed that count density within the anterior defect improved to normal but the lateral reductions persisted, and in two of these three studies the arms-down transmission map was distorted. Population mean segmental relative uptake values for NC arms-down studies were lower than for AC arms-down studies apart from three anterolateral segments where NC arms-down values were higher. Of 28 AC arms-down studies, 11 (39%) were of reduced quality compared with NC arms-up studies because of poorer spatial resolution and because AC enhances liver activity compared with NC. It is concluded that arm positioning influences reconstructed tomographic images depicting regional 201T1 distribution, particularly anterolaterally. There is lateral undercorrection in approximately 10% of AC arms-down studies, possibly because of attenuation map truncation. Image quality is reduced in about one-third of AC armsdown studies compared with NC arms-up studies. These data suggest that this attenuation correction method is not sufficiently robust to allow routine acquisition of MPI data with the arms down.

Radionuclide imaging of the heart.

Nuclear cardiology is an established part of diagnosis and assessment of patients with possible heart disease, the two most common tests being myocardial perfusion imaging and radionuclide ventriculography. Myocardial perfusion imaging comprises approximately 75% of nuclear cardiology studies in the UK, and is used in diagnosis and management of coronary artery disease.

Nuclear cardiology in the UK: British Nuclear Cardiology Society survey 1994.

This study surveyed practice in nuclear cardiology in the UK in 1994. A questionnaire was sent to 219 centres performing nuclear imaging asking for details of current practice in nuclear cardiology. Replies were received from 192 centres (88%). Activity in performance of myocardial perfusion imaging (MPI) and radionuclide ventriculography (RNV), anticipated changes in activity, differences between regional and district general hospitals, technical imaging parameters and referral sources were surveyed. Of the responding centres, 125 (65%) performed nuclear cardiology. More regional centres (85 vs 55%, P < 0.0003) performed a higher proportion (62 vs 24%, P < 0.001) of nuclear cardiology activity compared with district general hospitals. Nuclear medicine activity was estimated at 9.3 scans/1000/year, of which 8.9% was cardiology (0.82/1000/year; MPI, 0.56/1000/year; RNV, 0.26/1000/year). A comparison with previous surveys showed a significant increase of 24% in nuclear cardiology since 1988, with a strong rise in MPI (350%); however, RNV has fallen by 47%. Myocardial perfusion activity in the UK remains very low (25 and 5% for MPI and RNV respectively) when compared with the average of 2.2/1000/year for Europe and 10.8/1000/year for the USA. In conclusion, MPI has increased on average by 23% per annum (compound rate) since 1988, but in 1994 was still only 32% of the British Cardiac Society target of 2.6 scans/1000/year. Proper resourcing for capital expenditure on new equipment and new staff will be important to maintain momentum in closing the gap. Also important is clinical understanding, as already implemented by including nuclear cardiology in guidelines for specialist cardiology training.

Iodine-131-MIBG therapy of a patient with carcinoid liver metastases.

UNLABELLED: Iodine-13I-metaiodobenzylguanidine (MIBG) is highly concentrated by >60% of carcinoid metastases and thus provides a therapeutic opportunity. METHODS: A symptomatic patient with carcinoid liver metastases, unresponsive to chemotherapy combined with interferon-alpha, was subsequently treated with 131I-MIBG. RESULTS: Radionuclide therapy, which was without significant side effects, resulted in symptomatic improvement and reduced urinary 5-hydroxyindoleacetic acid levels. No new metastases were observed for 15 mo after 131I-MIBG therapy. Gross cystic change occurred in existing liver metastases, presumably as a result of ischemic necrosis. Surgical deroofing and aspiration of cysts led to regeneration of normal liver tissue. CONCLUSION: Iodine-131-MIBG therapy can provide prolonged symptomatic relief and improved quality of life in patients with metastatic carcinoid disease unresponsive to other therapies. The antitumor effect of 131I-MIBG was accompanied by few side effects, suggesting that this therapy should be considered in symptomatic patients with an early stage of disease.

Nuclear cardiology in the UK 1994: activity relative to Europe, USA, and British Cardiac Society targets.

OBJECTIVE: To survey practice in nuclear cardiology in the UK in 1994. DESIGN: A questionnaire was sent to 219 centres performing nuclear imaging asking for details of current practice in nuclear cardiology. Replies were received from 192 centres (88%). MAIN OUTCOME MEASURES: Activity in performance of myocardial perfusion imaging (MPI) and radionuclide ventriculography (RNV), anticipated changes in activity, differences between regional and district hospitals, technical imaging parameters, and referral sources. RESULTS: Of the responding centres, 125 (65%) performed nuclear cardiology procedures. More regional than district hospitals performed nuclear cardiology procedures (85% v 55%, p < 0.0003) and regional centres performed a higher proportion (62% v 24%, p < 0.001) of nuclear cardiology activity. Nuclear cardiology activity was 0.82 scans per 1000 population per year (MPI 0.56, RNV 0.26). There has been a significant increase (24%) in nuclear cardiology since 1988. There has been a pronounced rise in MPI (350%) while RNV has fallen by 47%. Myocardial perfusion activity in the UK remains very low (25% and 5% in regional and district hospitals, respectively) compared with the 1994 figures of 2.2/1000/year for Europe or 10.8/1000/year for the USA. CONCLUSIONS: MPI has increased on average by 23%/annum (compound rate) since 1988, but in 1994 was still only 32% of the British Cardiac Society target of 2.6/1000/year. Proper resources for capital expenditure on new equipment and new staff will be important to maintain momentum in closing the gap. Also important is improved clinical understanding, as already implemented by including nuclear cardiology in guidelines for specialist cardiology training.

Quality assurance in myocardial perfusion tomography: a collaborative BNCS/BNMS audit programme. British Nuclear Cardiology Society/British nuclear Medicine Society.

The aim of this study was to assess the status of acquisition and reporting of myocardial perfusion tomography in the UK. Centres were asked to provide an expert panel with clinical and technical information, digital and hard copy of raw data and reconstructed tomograms, as well as their report (optional) for five randomly selected studies. Ninety studies were received from 18 centres; report text was provided for 66 studies. Six parameters (stress technique, radiopharmaceutical usage, image acquisition and processing, report images and text) were scored as good (2), adequate (1) or poor (0) by consensus. Centres received the quality scores for each study and a consensus clinical report from the panel. Stress technique was scored as inadequate in 10 (11%) studies, radiopharmaceutical usage and image acquisition as inadequate in 5 (6%) studies, image processing as inadequate in 8 (10%) studies and report images as inadequate in 2 (3%) studies. Report text was felt to be inadequate in 21 of 66 (32%) studies; in 11 of these (52%), the report text was judged to be incorrect and in 10 (48%) it was essentially correct but misleading because of poor phraseology. The mean quality score per study was 1.3 (range 0.5-2.0). Seventeen of 88 (19%) studies scored less than 1.0 and were considered to be of poor quality. In conclusion, a large variation in standards of myocardial perfusion tomography was seen. Data acquisition was generally satisfactory, but 32% of reports were inadequate.

Clinical evaluation of technetium-99m-L,L-ethylenedicysteine in patients with chronic renal failure.

UNLABELLED: Technetium-99m-L,L-ethylenedicysteine (99mTc-L,L-EC), a new renal radiopharmaceutical, has been shown to have similar excretion characteristics but a higher plasma clearance than 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) in normal volunteers and patients with obstructive nephropathy. This study evaluated 99mTc-L,L-EC in patients with chronic renal failure. METHODS: The clearance of 99mTc-L,L-EC was compared with that of 125l-hippuran in 26 patients with varying degrees of chronic renal impairment (serum creatine 168-1163 mumol/liter). All 26 patients also were imaged with 99mTc-L,L-EC (70-80 MBq). Fifteen patients had further imaging with 99mTc-MAG3 (100 MBq) the following day. RESULTS: A subjective analysis of the 99mTc-L,L-EC images revealed that all were of acceptable quality regardless of creatinine level. In the 15 patients who were imaged with both 99mTc-L,L-EC and 99mTc-MAG3, general image quality and target-to-background ratios were similar. Time-activity curves and mean parenchymal transit times obtained with the two agents were almost identical. Plasma clearance values (mean +/- s.d.) of 99mTc-L,L-EC and 125l-hippuran were 81 +/- 68 ml/min and 114 +/- 104 ml/min, respectively. Mean 99mTc-L,L-EC clearance was 71% of the mean 125l-hippuran value. CONCLUSION: Technetium-99m-L,L-EC provides equally high-quality images to 99mTc-MAG3 in patients with chronic renal failure. Technetium-99m-L,L-EC clearance more closely resembles that of hippuran than does 99mTc-MAG3 clearance. These features together with its ease of preparation make 99mTc-L,L-EC an attractive alternative to 99mTc-MAG3 in patients with chronic renal failure.

Transmission scanning for attenuation correction of myocardial 201Tl images in obese patients.

For attenuation correction (AC) of 201Tl myocardial perfusion images, an accurate attenuation map is required. This study assessed whether prolonged transmission scanning is required in obese compared to normal-sized patients. Twenty-nine obese patients (mean body mass index 33 kg m-2) underwent sequential emission/transmission imaging for AC using an L-shaped, dual-headed gamma camera fitted with two 153Gd scanning line sources. Transmission data were acquired for 5 s per view (scan time for normal-sized patients) and for 10 s per view and used to reconstruct individual attenuation maps. Emission data were reconstructed using each attenuation map in turn to produce attenuation-corrected images (AC5 and AC10). Tracer distribution in the AC5 and AC10 images was compared by two observers blinded to study type. For each data set, count density was measured in 17 segments of a polar plot and segmental uptake expressed relative to study maximum. Although myocardial count density was low on the 5 s per view transmission images (0.5-13.0 and 3.0-14.0 counts per pixel in the anteroposterior and lateral projections respectively), no significant differences in tracer distribution were seen between the AC5 and AC10 images and these were reported identically. In addition, the mean segmental relative uptake values were similar (P > 0.05) for corresponding segments of the AC5 and AC10 images. We conclude that prolonged transmission scanning is not required in obese compared to normal-sized patients. The transmission scanning protocol used in normal-sized patients is applicable across a wide patient weight range.