Use of a corporate needs assessment to define the information requirements of an arthritis resource centre in Birmingham: comparison of patients' and professionals' views

OBJECTIVES

Education and information are important components of the management of chronic disease, though provision of these in the routine clinic setting may be suboptimal. We carried out a corporate needs assessment, both to evaluate stakeholders' perceived usefulness of potential facilities that could be offered by a community-based arthritis resource centre in Birmingham and to compare the views of patients with rheumatological conditions and health professionals.

METHODS

Rheumatology patients (n = 201 responders/309 contacted) and health professionals (n = 232/430) were asked to complete a questionnaire to assess both current rheumatology service provision and perceived needs for further information that could be offered within the proposed resource centre. Views of patients and professionals were compared using odds ratios. Logistic regression analysis determined patient characteristics associated with perceived usefulness of various information types.

RESULTS

The overall response rate was 58%. Most patients were currently receiving medication but only 38% received written information on arthritis. Over 80% of responders felt that more information would be useful, particularly information in written leaflets. Compared with professionals, patients gave higher value to certain types of medical, non-medical, support and skills information, particularly individual information from trained volunteers, and specific information on benefits, diet and alternative therapy, and symptom management. Non-Caucasian patients gave higher value to the provision of material in different languages and the availability of multilingual volunteer staff.

CONCLUSION

Rheumatology patients and professionals identified a relative lack of information for patients. There was wide interest in the provision of more information, with value placed on the provision of material in different languages, at an educational resource centre. This work has been used to develop the facilities currently offered at the Birmingham Arthritis Resource Centre. Further research is needed to investigate the effectiveness of the provision of good quality information to patients with arthritis.

Functional CT imaging in oncology

The two-compartment pharmacokinetics exhibited by iodinated contrast media makes these agents well suited to the study of tumour angiogenesis in which new vessels are not only produced in greater number but also are abnormally permeable to circulating molecules. The temporal changes in contrast enhancement of tumours on CT have been shown to correlate with histopathological assessments of angiogenesis with the intravascular and extravascular phases of contrast enhancement reflecting microvessel density and vascular permeability, respectively. By quantifying tumour contrast enhancement to capture physiological information about the vascular system, functional CT can provide a useful adjunct to the anatomical information afforded by MDCT in oncology, aiding with tumour diagnosis, risk stratification and therapy monitoring. By simultaneously assessing tumour vascularity and metabolic demand, the broader expansion of integrated MDCT/PET imaging will support highly sophisticated assessments of tumour biology within a single examination.

Cancer imaging: is it cost-effective?

With expenditure on imaging patients with cancer set to increase in line with rising cancer prevalence, there is a need to demonstrate the cost-effectiveness of advanced cancer imaging techniques. Cost-effectiveness studies aim to quantify the cost of providing a service relative to the amount of desirable outcome gained, such as improvements in patient survival. Yet, the impact of imaging on the survival of patients with cancer is small compared to the impact of treatment and is therefore hard to measure directly. Hence, techniques such as decision-tree analysis, that model the impact of imaging on survival, are increasingly used for cost-effectiveness evaluations. Using such techniques, imaging strategies that utilise computed tomography, magnetic resonance imaging and positron emission tomography have been shown to be more cost-effective than non-imaging approaches for the management of certain cancers including lung, prostate and lymphoma. There is stronger evidence to support the cost-effectiveness of advanced cancer imaging for diagnosis, staging and monitoring therapy than for screening. The results of cost-effectiveness evaluations are not directly transferable between countries or tumour types and hence more studies are needed. As many of the techniques developed to assess the evidence base for therapeutic modalities are not readily applicable to diagnostic tests, cancer imaging specialists need to define the methods for health technology assessment that are most appropriate to their speciality.

Cancer imaging - making the most of your gamma camera

As MRI threatens the use of bone scintigraphy for skeletal metastases and 18F-fluorodeoxyglucose positron emission tomography (18FDG-PET) emerges as the main focus in nuclear oncology, the future role of the gamma camera in cancer imaging appears unclear. However, there is a range of pre-existing conventional gamma camera techniques that have incremental benefit over CT and other structural imaging techniques, but are yet to be fully exploited in the care of cancer patients. This article reviews some of the more advanced conventional nuclear medicine techniques for cancer imaging. Often gamma camera techniques perform close to 18FDG - PET or provide complementary information.Where 18FDG - PET is diagnostically superior, the incremental cost-effectiveness gain of 18FDG - PET over conventional gamma camera techniques has not always been fully evaluated.

Solitary pulmonary nodules: impact of quantitative contrast-enhanced CT on the cost-effectiveness of FDG-PET

AIM

To determine the impact of quantitative contrast-enhanced computed tomography (QECT) on the cost-effectiveness of diagnostic strategies for the assessment of solitary pulmonary nodules (SPNs).

MATERIALS AND METHODS

Four diagnostic strategies were evaluated using decision tree analysis: conventional CT alone; conventional CT followed by QECT; conventional CT followed positron emission tomography (PET); and conventional CT followed by QECT and PET (QECT+PET). The average cost per patient, accuracy of management and incremental cost:accuracy ratio (ICAR) were determined for each strategy. Although baseline assumptions reflected the Australian setting, sensitivity analysis was used to extrapolate the results to the UK.

RESULTS

At the baseline prevalence of malignancy (54%) and cost of PET relative to surgery (16%), the QECT strategy incurs the least cost (5560 dollars/patient) but the QECT+PET strategy is the most cost-effective (ICAR 12,059 dollars/patient). At reported levels of disease prevalence (68.5%) and cost of PET relative to surgery (29.9%) in the UK, the QECT strategy is the most cost-effective.

CONCLUSION

QECT offers a cost-effective approach to evaluation of SPNs. Whether QECT is used alone or in combination with PET will depend upon local availability and regional values for prior probability of malignancy within SPNs and the cost of PET relative to surgery.

Pancreatic cancer: preliminary experience with sodium iodide fluorodeoxyglucose positron emission tomography in Australia

Previous studies of fluorodeoxyglucose positron emission tomography (FDG-PET) in pancreatic cancer have used Bismuth Germinate detector systems. This preliminary Australian study aims to confirm the accuracy of FDG-PET in pancreatic cancer using a dedicated sodium iodide (NaI) PET system. Fifteen consecutive patients underwent FDG-PET using a GE QUEST dedicated NaI PET scanner. The indications were the characterization of a pancreatic mass seen on CT or ultrasonographic imaging (nine cases), diagnosis or exclusion of recurrent disease following surgery and adjuvant therapy (four cases) and presurgical staging of primary pancreatic cancer (two cases). The final diagnosis was determined from histology or, when no histology was available, by radiological and clinical follow up. The FDG-PET accurately characterized eight out of nine pancreatic masses (seven were true negative, one was true positive and one was false positive). Of the four cases performed to determine recurrent disease, three were accurately diagnosed (two true negatives and one true positive). In the fourth case, PET accurately detected a liver metastasis but did not detect the local recurrence. Results in the two cases where PET was performed for preoperative staging comprised one true positive and one false negative. Sodium iodide FDG-PET is useful in the diagnosis of pancreatic cancer, particularly in the presence of a previously detected mass.

Functional computed tomography in oncology

Functional Computed Tomography (CT) describes the use of existing technologies and conventional contrast agents to capture physiological parameters that reflect the vasculature within tumours and other tissues. The technique is readily incorporated into routine conventional CT examinations and, in tumours, the physiological parameters obtained provide an in-vivo marker of angiogenesis. As well as providing a research tool, functional CT has clinical applications in tumour diagnosis, staging, risk stratification and therapy monitoring, including the characterisation of pulmonary nodules, detection of occult hepatic metastases, grading of cerebral glioma and monitoring of anti-angiogenesis drugs. With the recent commercial availability of appropriate software and the development of multislice CT systems, functional CT is poised to make a significant impact upon the imaging of patients with cancer.

Computed tomography perfusion imaging in acute stroke

The development of thrombolytic and neuroprotective agents for the treatment of acute stroke has created an imperative for improved imaging techniques in the assessment of acute stroke. Five cases are presented to illustrate the value of perfusion CT in the evaluation of suspected acute stroke. To obtain the perfusion data, a rapid series of images was acquired without table movement following a bolus of contrast medium. Cerebral blood flow, cerebral blood volume and mean transit time were determined by mathematically modelling the temporal changes in contrast enhancement in the brain and vascular system. Pixel-by-pixel analysis allowed generation of perfusion maps. In two cases, CT-perfusion imaging usefully excluded acute stroke, including one patient in whom a low-density area on conventional CT was subsequently proven to be tumour. Cerebral ischaemia was confirmed in three cases, one with an old and a new infarction, one with a large conventional CT abnormality but only a small perfusion defect, and one demonstrating infarct and penumbra. Perfusion CT offers the ability to positively identify patients with non-haemorrhagic stroke in the presence of a normal conventional CT, to select those cases where thrombolysis is appropriate, and to provide an indication for prognosis.

Solitary pulmonary nodules: accuracy and cost-effectiveness of sodium iodide FDG-PET using Australian data

This study uses Australian data to confirm the accuracy of dedicated sodium iodide (NaI) fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in evaluating indeterminate solitary pulmonary nodules (SPNs) and to determine the conditions under which PET could play a cost-effective role in this evaluation. Ninety-two patients from two Australian hospitals in different states underwent FDG-PET for evaluation of an SPN. Observed values for prior probability of malignancy and diagnostic accuracy of PET were applied to previously published decision tree models using published Australian health care costs. The accuracy of FDG-PET was 93% with a sensitivity of 92% and a specificity of 95%. The prior probability of malignancy (0.54), PET sensitivity and PET specificity indicated cost savings per patient of up to EUR 455 (Adollars 774) based on a PET cost of EUR 706 (Adollars 1,200). PET would remain cost-effective for levels of prior probability up to 0.8-0.9 and a PET cost of EUR 736-1,161 (Adollars 1,252-Adollars 1,974). It is concluded that NaI PET is accurate, cost saving and cost-effective for the characterisation of indeterminate pulmonary nodules in Australia. Comparison with previous reports from the United States confirms that FDG-PET can remain cost-effective despite population differences in medical costs, disease prevalence and PET diagnostic performance.

Hepatic haemodynamics: interrelationships between contrast enhancement and perfusion on CT and Doppler perfusion indices

This study compares three techniques that evaluate hepatic haemodynamics for the detection of metastatic liver disease to determine the interrelationships between the techniques and to assess their equivalence. The three techniques studied were dedicated CT measurements of hepatic enhancement, CT measurements of perfusion and Doppler perfusion indices. 53 patients with proven malignancies of either breast or colon underwent a single location dynamic CT for measurement of hepatic perfusion and enhancement, whilst a subset of 12 patients underwent both CT perfusion and Doppler perfusion studies. Statistically significant correlations were found between CT arterial phase enhancement and CT arterial perfusion (r=0.612, p<0.001), and between both of these parameters and Doppler arterial flow (r=0.867, p<0.001 and r=0.842, p<0.001, respectively). Significant correlations were also found between both the ratio of CT arterial enhancement to peak enhancement and the CT arterial perfusion with the Doppler perfusion index (r=0.797, p=0.002 and r=0.725, p=0.008, respectively). Combined CT arterial and portal perfusion correlated with peak liver enhancement (r=0.614, p< 0.001), but Doppler measurements of portal flow did not correlate with any CT parameter. Increased arterial enhancement, perfusion or flow are valuable additional radiological signs for the presence of hepatic metastases that can be elicited by incorporating any one of these methods into existing imaging protocols.

Standardized perfusion value: universal CT contrast enhancement scale that correlates with FDG PET in lung nodules

The standardized enhancement value and standardized perfusion value allow comparison between different methods for quantification of contrast enhancement during computed tomography (CT). Standard perfusion values calculated from CT measurements of perfusion within pulmonary nodules compared favorably with those derived from previously reported enhancement data and correlated with standardized uptake values obtained from positron emission tomographic images (r = 0.8, P <.01).

An approach to demonstrating cost-effectiveness of diagnostic imaging modalities in Australia illustrated by positron emission tomography

The aim of this study was to develop a framework in which the cost-effectiveness of new imaging technologies could be evaluated using data from other countries, while assessing the impact that any differences between the study populations and Australia may have upon the results. Publications reporting the cost-effectiveness or therapeutic impact of positron emission tomography (PET) were re-worked using Australian cost structures. PET was assigned a cost of $950. The effects of potential differences between the populations studied and the Australian population were evaluated by applying sensitivity analysis to those publications that describe decision tree methodology. The parameters included in the sensitivity analysis were disease prevalence and specificity of PET. The Australian cost savings per patient examined by PET were $505.50-$912.41 for investigation of solitary pulmonary nodules, $34.65-$360.03 for lung cancer staging, $550.08 for axillary staging of breast cancer, $230.75-$2301.27 for assessment of recurrent colorectal cancer and $300.24-$2069.65 for assessment of myocardial viability. Significant differences in disease prevalence and PET specificity could occur while the cost-effectiveness of PET was preserved. Decision tree sensitivity analysis can demonstrate the cost-effectiveness of diagnostic imaging modalities in Australia and provides indications that PET is cost-effective for a range of clinical indications.

Assessment of quantitative computed tomographic cerebral perfusion imaging with H2(15)O positron emission tomography

Assessment of quantitative cerebral blood flow on a conventional fast CT machine without the use of specialized equipment may be valuable in the investigation of acute stroke and head injury. We aimed to compare a single slice CT perfusion sequence with H2(15)O positron emission tomography using the sagittal sinus as an input function, a method that avoids unnecessary orbital irradiation. Eight patients were studied, two patients with gliomas, and six with arteriovenous malformations. The dynamic CT perfusion sequence was performed by acquiring the same 10 mm slice 10 times over 30 sec during a 50 ml bolus of intravenous contrast medium given at a rate of 7.5 ml sec-1 using a power injector. The CT perfusion studies were completed without complication. Co-registration was sub-optimal in one patient. Overall the correlation between the two methodologies was encouraging with an average r2 value of 0.524 for individual analyses. When two patients with high flow arteriovenous malformations were excluded the average r2 value increased to 0.640. The results of this CT perfusion methodology are encouraging. Having shown its feasibility, further studies in conditions with lower rates of cerebral blood flow are warranted.

CT measurement of perfusion and permeability within lymphoma masses and its ability to assess grade, activity, and chemotherapeutic response

PURPOSE

Structural CT criteria such as nodal size and appearance have a poor correlation with the grade and activity of a lymphoma mass. This study investigates the potential for functional CT perfusion and permeability measurements to assess lymphoma grade and activity.

METHOD

Thirty-nine patients with proven lymphoma underwent 47 dynamic contrast-enhanced CT studies. Lymphoma grade was classified as low or intermediate/high. In seven patients who underwent repeated studies, measurements were correlated against change in disease activity in the intervening period.

RESULTS

Median perfusion values were higher in active disease (0.55 vs. 0.37 ml/min/ml) and intermediate/high-grade lymphoma (0.56 vs. 0.46 ml/min/ml). Perfusion below 0.2 ml/min/ml implied inactive disease (p < 0.03), whereas > 0.5 ml/min/ml suggested intermediate/high-grade lymphoma (p = 0.11). Median values of permeability were little different between patient groups. Only perfusion fell when disease became inactive.

CONCLUSION

Only CT perfusion measurements of nodes have potential for assessing lymphoma grade, activity, and treatment response.

Tumour angiogenesis and its relation to contrast enhancement on computed tomography: a review

Angiogenesis describes the formation of new blood vessels within tumours. The process is essential for tumour growth and metastasis. The development of new vessels leads to physiological changes, specifically increased perfusion, blood volume and capillary permeability, that alter contrast enhancement during computed tomography (CT). Functional CT techniques that quantify these physiological changes can provide greater insight into how angiogenesis alters contrast enhancement in routine practice and also serve as diagnostic tools in their own right. The functional information obtained can aid with tissue characterisation, such as type or grade of tumour, improve the detection of hepatic metastases, produce clearer delineation of tumours with benefits for radiotherapy planning and biopsy, and provide prognostic information. By providing a marker for tumour angiogenesis, quantitative contrast enhanced CT can improve the diagnostic assessment of patients with cancer.

Blood-brain barrier and blood volume imaging of cerebral glioma using functional CT: a pictorial review

We present five cases of cerebral glioma that illustrate the benefit of functional CT imaging of blood-brain barrier permeability and cerebral blood volume. Functional CT uses Patlak analysis of a single location dynamic sequence to extract physiological information that is useful clinically in the assessment of cerebral gliomas. Functional CT offers distinct advantages over other functional modalities, including clearer delineation of tumour, tumour grading, measurement of tumour activity and monitoring response to therapy.

Hepatic metastases: the value of quantitative assessment of contrast enhancement on computed tomography

OBJECTIVE

Occult and overt hepatic metastases have been the target of research in an effort to improve detection and characterisation of cancer spread and, consequently, guidance of treatment. This paper aims to illustrate the value of two quantitative techniques for assessing contrast enhancement during CT in the detection of hepatic metastases. It outlines the applications to which they can be put, and the ease of incorporation into current protocols.

METHODS AND MATERIAL

The first technique, perfusion CT, uses a single location dynamic CT sequence to obtain time attenuation data whilst a short, high concentration IV bolus of contrast passes through the abdominal vasculature. Quantitative hepatic arterial and portal values are calculated, along with a perfusion image map. The second technique uses densitometric analysis during a modified contrast enhanced dual-phase liver CT examination. Semi-quantitative values are calculated from the images obtained at the 25 and 40 s times.

RESULTS

Both perfusion CT and densitometric analysis have been to shown to differentiate between normal and tumour-bearing liver as defined by structural CT. Hepatic metastases are associated with increased arterial perfusion and arterial phase enhancement. Increased arterial phase enhancement on densitometric analysis in the absence of overt lesions heralds the onset of visible metastases in the liver in the ensuing 18 months. Perfusion CT has also demonstrated a correlation between high arterial perfusion around a visible metastasis and increased survival.

CONCLUSION

Both techniques can provide more information than is available from conventional enhanced CT scans alone. An algorithm for the clinical application of perfusion CT is proposed. The ease with which these quantitative techniques can be performed and the extra information they provide could lead to improved staging of cancer and more appropriate patient management.

A new non-invasive test for the detection of compartment syndromes

Chronic exertional compartment syndrome (CECS) is currently diagnosed using invasive pressure measurements. We report the use of 99Tcm-methoxyisobutyl isonitrile (99Tcm-MIBI) scintigraphy as a new non-invasive method of diagnosis. Forty-six patients with suspected chronic compartment syndrome underwent graded treadmill exercise to reproduce the presenting symptoms. At peak exercise, 300 MBq of 99Tcm-MIBI were injected intravenously. Subsequent cross-sectional imaging provided by emission tomography demonstrated regional abnormalities in muscle perfusion in the calf. A repeat study was performed at rest the following day. All patients in whom there was a strong clinical suspicion of CECS were considered for invasive pressure measurements. Statistical analysis of the results for investigation of CECS using 99Tcm-MIBI versus pressure studies gave P = 0.06. A comparison of 99Tcm-MIBI versus outcome gave P < 0.0001. The sensitivity was 80% and the specificity 97% for 99Tcm-MIBI studies based on outcome. The positive predictive value was 89% and the negative predictive value 94%. Thus 99Tcm-MIBI can detect compartment syndromes with good positive and negative predictive values. It is relatively simple, cheap and less invasive than pressure measurements. This technique shows promise in the diagnosis of CECS.

CT derived Patlak images of the human kidney

This study aimed to produce Patlak images of the kidney from dynamic CT data and to determine whether such images are substantially affected by fluid movement between renal tubular segments. Renal permeability was measured in 31 kidneys by applying Patlak analysis to time-density data from kidney and aorta during dynamic CT. Permeability parameters were correlated against plasma urea. The renal region (cortex or medulla) with the greatest permeability was determined from parametric images generated using pixel by pixel analysis. The mean value for whole kidney permeability was 517.5 microliters min-1 ml-1. A correlation was found between whole kidney permeability and plasma urea (p < 0.01). Permeability values were highest in the renal medulla in 24 (77%) kidneys. The higher medullary values of permeability are artefactual, resulting from movement of fluid and contrast medium between cortex and medulla. Although Patlak images do not reflect true intrarenal permeability values, the apparent medullary permeability may provide diagnostically useful information about the concentrating ability of the kidney. CT measurements of whole kidney permeability reflect filtration function but the apparent intrarenal variations in permeability will result in measurement errors dependent upon the relative amounts of renal cortex and medulla included in the CT slice studied.

Blood-brain barrier and blood volume imaging of cerebral glioma using functional CT: a pictorial review

Five cases of cerebral glioma are presented here that illustrate the benefit of functional CT imaging of blood-brain barrier permeability and cerebral blood volume. Functional CT uses Patlak analysis of a single location dynamic sequence to extract physiological information that is useful clinically i the assessment of cerebral gliomas. Functional CT offers distinct advantages over other functional modalities including clearer delineation of tumour, tumour grading, measurement of tumour activity and monitoring response to therapy.