Pancreatic cancer: cost-effectiveness of imaging technologies for assessing resectability

Cross-sectional imaging after pancreatic surgery: The dialogue between the radiologist and the surgeon

Pancreatic surgery is nowadays considered one of the most complex surgical approaches and not unscathed from complications. After the surgical procedure, cross-sectional imaging is considered the non-invasive reference standard to detect early and late compilations, and consequently to address patients to the best management possible. Contras-enhanced computed tomography (CECT) should be considered the most important and useful imaging technique to evaluate the surgical site. Thanks to its speed, contrast, and spatial resolution, it can help reach the final diagnosis with high accuracy. On the other hand, magnetic resonance imaging (MRI) should be considered as a second-line imaging approach, especially for the evaluation of biliary findings and late complications. In both cases, the radiologist should be aware of protocols and what to look at, to create a robust dialogue with the surgeon and outline a fitted treatment for each patient.

Additional MRI for initial M-staging in pancreatic cancer: a cost-effectiveness analysis

OBJECTIVE

Pancreatic cancer is portrayed to become the second leading cause of cancer-related death within the next years. Potentially complicating surgical resection emphasizes the importance of an accurate TNM classification. In particular, the failure to detect features for non-resectability has profound consequences on patient outcomes and economic costs due to incorrect indication for resection. In the detection of liver metastases, contrast-enhanced MRI showed high sensitivity and specificity; however, the cost-effectiveness compared to the standard of care imaging remains unclear. The aim of this study was to analyze whether additional MRI of the liver is a cost-effective approach compared to routinely acquired contrast-enhanced computed tomography (CE-CT) in the initial staging of pancreatic cancer.

METHODS

A decision model based on Markov simulation was developed to estimate the quality-adjusted life-years (QALYs) and lifetime costs of the diagnostic modalities. Model input parameters were assessed based on evidence from recent literature. The willingness-to-pay (WTP) was set to $100,000/QALY. To evaluate model uncertainty, deterministic and probabilistic sensitivity analyses were performed.

RESULTS

In the base-case analysis, the model yielded a total cost of $185,597 and an effectiveness of 2.347 QALYs for CE-MR/CT and $187,601 and 2.337 QALYs for CE-CT respectively. With a net monetary benefit (NMB) of $49,133, CE-MR/CT is shown to be dominant over CE-CT with a NMB of $46,117. Deterministic and probabilistic survival analysis showed model robustness for varying input parameters.

CONCLUSION

Based on our results, combined CE-MR/CT can be regarded as a cost-effective imaging strategy for the staging of pancreatic cancer.

KEY POINTS

• Additional MRI of the liver for initial staging of pancreatic cancer results in lower total costs and higher effectiveness. • The economic model showed high robustness for varying input parameters.

A systematic review of economic evaluation in pancreatic ductal adenocarcinoma

OBJECTIVES

The economic evaluation (EE) of healthcare interventions has become a necessity. However, high quality needs to be ensured in order to achieve validated results and help making informed decisions. Thus, the objective of the present study was to systematically identify and review published pancreatic ductal adenocarcinoma-related EEs and to assess their quality.

METHODS

Systematic literature research was conducted in PubMed and Cochrane to identify published EEs between 2000 and 2015. The quality of each selected EE was assessed by two independent reviewers, using the Drummond's checklist.

RESULTS

Our systematic review was based on 32 EEs and showed a wide variety of methodological approaches, including different perspectives, time horizon, and cost effectiveness analyses. Nearly two-thirds of EEs are full EEs (n = 21), and about one-third of EEs had a Drummond score ≥7, synonymous with 'high quality'. Close to 50% of full EEs had a Drummond score ≥7, whereas all of partial EEs had a Drummond score <7 (n = 11).

CONCLUSIONS

Over the past 15 years, a lot of interest has been evinced over the EE of pancreatic ductal adenocarcinoma (PDAC) and its direct impact on therapeutic advances in PDAC. To provide a framework for health care decision-making, to facilitate transferability and to lend credibility to health EEs, their quality must be improved. For the last 4 years, a tendency towards a quality improvement of these studies has been observed, probably coupled with a context of rational decision-making in health care, a better and wider spread of recommendations and thus, medical practitioners' full endorsement.

Dual-phase 18F-FDG PET/CT imaging in the characterization of pancreatic lesions: does it offer prognostic information?

OBJECTIVE

The primary aim of our prospective study was to evaluate the usefulness of dual-phase F-fluoro-deoxy-glucose PET/computed tomography (F-FDG PET/CT) in the characterization of pancreatic masses. The secondary aim was to assess whether delayed imaging revealed any prognostic information.

MATERIALS AND METHODS

Fifty patients with periampullary or pancreatic masses on conventional imaging were included in this study. Early and delayed PET/CT was performed, followed by pathological examination in all patients. PET/CT parameters including uptake pattern, SUVearly, SUVdelayed, lesion to background ratio (L/B), and retention index (RI) were assessed for their ability to differentiate benign from malignant lesions. Patients with malignant lesions were followed up for a median duration of 26 months. The association of 11 variables with survival was analyzed by univariate and multivariate methods.

RESULTS

Thirty-one patients had malignant lesions and 19 had benign lesions. The mean SUVearly, L/B, SUVdelayed, and RI between the malignant and benign lesions were statistically significant. The F-FDG uptake pattern of the lesions had higher sensitivity (93.5%) and specificity (100%) compared with RI (cutoff 25.7%) (84 and 37%, respectively) for diagnosing malignancy (P<0.05). In univariate analysis both RI (>18.7%) and tumor size (>2.6 cm) predicted significantly poor survival, whereas in multivariate analysis RI (P=0.04) was the only predictor of poor survival.

CONCLUSION

Dual-phase F-FDG PET/CT is not useful in characterizing pancreatic masses as it cannot differentiate benign from malignant lesions, and focal uptake on early PET imaging is the best indicator of malignancy. A possible benefit in performing a delayed scan is that a high RI (>18.7) can predict poor survival and hence may be useful in treatment planning.

Novel imaging strategies for upper gastrointestinal tract cancers

Accurate pretherapeutic imaging is the cornerstone of all cancer treatment. Unfortunately, modern imaging modalities have several unsolved problems and limitations. The differentiation between inflammation and cancer infiltration, false positive and false negative findings as well as lack of confirming biopsies in suspected metastases may have serious negative consequences in cancer patients. This review describes some of these problems and challenges the use of conventional imaging by suggesting new combined strategies that include selective use of confirming biopsies and complementary methods to detect microscopic cancer dissemination.

Assessing the appropriateness of outpatient abdominopelvic CT and MRI examinations using the American College of Radiology Appropriateness Criteria

RATIONALE AND OBJECTIVES

To retrospectively assess the appropriateness of outpatient abdominal and pelvic computed tomography (CT) and magnetic resonance imaging (MRI) examinations using the American College of Radiology Appropriateness Criteria (AC).

MATERIALS AND METHODS

A total of 570 adult outpatient abdominopelvic CT (304) and MRI (266) studies performed in a 1-month period with available documentation of the clinical encounter generating the imaging order were included. On the basis of review of the imaging report and patient record, examinations were classified in terms of match to a specific AC variant, appropriateness score, and the presence of a significant result. Data were analyzed using Fisher's exact test.

RESULTS

Forty-five percent of examinations matched an AC variant: 52% of CT and 38% of MRI (P < .001). Ninety-two percent of examinations matching the AC were appropriate: 96% of CT and 86% of MRI (P = .009). Appropriate examinations were more likely to provide a significant result than not appropriate studies (48% vs. 24%, P = .041). Although a significant result was related to the primary study indication more frequently in appropriate than not appropriate examinations, this difference was not significant (93% vs. 80%, respectively, P = .204). The most common indications not matching an AC were colon cancer follow-up (n = 14) and melanoma follow-up (n = 14) among CT, and hepatocellular carcinoma screening (n = 31) and elevated prostate-specific antigen (PSA) without prior biopsy (n = 14) among MRI.

CONCLUSIONS

Most examinations matching the AC were appropriate, and appropriate examinations were more likely to have a significant result. However, most examinations, including 62% of MRI, had no relevant clinical condition, highlighting a critical area for future AC expansion and modification.

Cost-effectiveness of the evaluation of a suspicious biliary stricture

BACKGROUND

Biliary stricture without mass presents diagnostic and therapeutic challenges because the poor sensitivity of the available tests and significant mortality and cost with operation.

METHODS

A decision model was developed to analyze costs and survival for 1) investigation first with endoscopic ultrasound (EUS) and fine needle aspiration, 2) investigation first with endoscopic retrograde cholangiopancreatography (ERCP) and brushing, or 3) surgery on every patient. The average age of someone with a biliary stricture was found to be 62-y-old and the rate of cancer was 55%. Incremental cost-effectiveness ratios (ICER) were calculated based on the change in quality adjusted life years (QALYs) and costs (US$) between the different options, with a threshold of $150,000 to determine the most cost-effective strategy. One-way, two-way, and probabilistic-sensitivity analysis were performed to validate the model.

RESULTS

ERCP results in 9.05 QALYs and a cost of $34,685.11 for a cost-effectiveness ratio of $3832.33. EUS results in an incremental increase in 0.13 QALYs and $2773.69 for an ICER of $20,840.28 per QALY gained. Surgery resulted in a decrease of 1.37 QALYs and increased cost of $14,323.94 (ICER-$10,490.53). These trends remained within most sensitivity analyses; however, ERCP and EUS were dependent on the test sensitivity.

CONCLUSIONS

In patients with a biliary stricture with no mass, the most cost-effective strategy is to investigate the patient before operation. The choice between EUS and ERCP should be institutionally dependent, with EUS being more cost-effective in our base case analysis.

Cost-effectiveness of prophylactic surgery for duodenal cancer in familial adenomatous polyposis

BACKGROUND

Duodenal cancer is the leading cause of cancer death in familial adenomatous polyposis after colorectal cancer. The lifetime risk for developing duodenal cancer is 4% to 10%. Current treatment guidelines recommend endoscopic surveillance with a prophylactic pancreaticoduodenectomy in advanced duodenal polyposis, defined using the Spigelman staging system. Because no clinical trials have assessed this recommendation, a modeling approach was used to evaluate the cost-effectiveness of various treatment strategies.

METHODS

A Markov model was constructed to estimate the life expectancy and cost of three different strategies: pancreaticoduodenectomy at Spigelman stage III, pancreaticoduodenectomy at Spigelman stage IV, and pancreaticoduodenectomy at cancer diagnosis. A cohort of 30-year-old familial adenomatous polyposis patients with total colectomies was simulated until age 80. The analysis was from a societal perspective. Extensive sensitivity analysis was performed to assess the impact of model uncertainty on results.

RESULTS

At all stages of polyposis and all ages <80 years, prophylactic surgery at Spigelman stage IV resulted in the greatest life expectancy. Surgery at stage IV was more effective and more expensive than surgery at cancer diagnosis, with an incremental cost of $3,200 per quality-adjusted life year gained. Surgery at stage III was not a viable option. The results were robust to wide variation in model parameters but were sensitive to the post-pancreaticoduodenectomy quality of life score.

CONCLUSIONS

Prophylactic pancreaticoduodenectomy at stage IV duodenal polyposis in familial adenomatous polyposis is a cost-effective approach that results in greater life expectancy than surgery at either stage III or cancer diagnosis.

Evolving preoperative evaluation of patients with pancreatic cancer: does laparoscopy have a role in the current era?

BACKGROUND

Recent years have brought important developments in preoperative imaging and use of laparoscopic staging of patients with pancreatic adenocarcinoma (PAC). There are few data about the optimal combination of preoperative studies to accurately identify resectable patients.

STUDY DESIGN

We conducted a statewide review of all patients with surgically managed PAC from 1996 to 2003 using data from the Oregon State Cancer Registry, augmented with clinical information from primary medical record review. We documented the use of all staging modalities, including CT, endoscopic ultrasonography, and laparoscopy. Primary outcomes included resection with curative intent. The association between staging modalities, clinical features, and resection was measured using a multivariate logistic regression model.

RESULTS

There were 298 patients from 24 hospitals who met the eligibility criteria. Patients were staged using a combination of CT (98%), laparoscopy (29%), and endoscopic ultrasonography (32%). The overall proportion of patients who went to surgical exploration and were resected was 87%. Of patients undergoing diagnostic laparoscopy, metastatic disease that precluded resection was discovered in 24 (27.6%). For patients who underwent diagnostic laparoscopy and were not resected, vascular invasion was the most common determinant of unresectability (56.6%). In multivariate analysis, preoperative weight loss and surgeon decision to use laparoscopy predicted unresectability at laparotomy.

CONCLUSIONS

This population-based study demonstrates that surgeons appear to use laparoscopy in a subset of patients at high risk for metastatic disease. The combination of current staging techniques is associated with a high proportion of resectability for patients taken to surgical exploration. With current imaging modalities, selective application of laparoscopy with a dual-phase CT scan as the cornerstone of staging is a sound clinical approach to evaluate pancreatic cancer patients for potential resectability.

Diagnostic ascertainment of suspicious pancreatic mass: a threshold analysis

BACKGROUND & AIMS

It is frequently difficult to differentiate between a benign and malignant pancreatic mass. The aim of this study was to assess the parameters that affect the decision to perform surgery on a suspicious pancreatic head lesion.

METHODS

A cost-benefit analysis, using decision tree and threshold analysis, accumulates costs and quality-adjusted life years in patients undergoing pancreaticoduodenectomy or expectant management. The threshold value is defined as the diagnostic probability for pancreatic cancer when the cost-benefit relationships of pancreaticoduodenectomy or expectant management are equal.

RESULTS

For a localized pancreatic head lesion, the threshold probability of cancer is 43%. Any higher probability of pancreatic cancer makes pancreaticoduodenectomy the preferred treatment option. Within a range of $20,000 to $80,000 spent on surgery, the threshold in favor of Whipple procedure remains relatively low at 40% to 65%. A reduced quality of life after surgery weighs against surgery and raises its threshold. Varying quality of life between 100% and 80% changes the threshold between 31% and 67%. The threshold also is increased in younger patients because of the potentially more dire consequences of unnecessary surgery in instances of long life expectancy.

CONCLUSIONS

Even if diagnostic certainty cannot be achieved, it frequently is beneficial to perform surgery despite the risk of subjecting the occasional patient with benign pancreatic head lesion to an unnecessary pancreaticoduodenectomy.

Progression elevated gene-3 promoter (PEG-Prom) confers cancer cell selectivity to human polynucleotide phosphorylase (hPNPase(old-35))-mediated growth suppression

The poor prognosis of pancreatic cancer patients using currently available therapies mandates novel therapeutics that combine anti-neoplastic potency with toxicity-minimizing cancer specificity. Employing an overlapping pathway screen to identify genes exhibiting coordinated expression as a consequence of terminal cell differentiation and replicative senescence, we identified human polynucleotide phosphorylase (hPNPase(old-35)), a 3',5'-exoribonuclease that exhibits robust growth-suppressing effects in a wide spectrum of human cancers. A limitation to the anti-neoplastic efficacy of hPNPase(old-35) relates to its lack of cancer specificity. The promoter of Progression Elevated Gene-3 (PEG-Prom), discovered in our laboratory via subtraction hybridization in a transformation progression rodent tumor model functions selectively in a diverse array of human cancer cells, with limited activity in normal cells. An adenovirus constructed with the PEG-Prom driving expression of hPNPase(old-35) containing a C-terminal Hemaglutinin (HA)-tag (Ad.PEG.hPNPase(old-35)) was shown to induce robust transgene expression, growth suppression, apoptosis, and cell-cycle arrest in a broad panel of pancreatic cancer cells, with minimal effects in normal immortalized pancreatic cells. hPNPase(old-35) expression correlated with arrest in the G(2)/M phase of the cell cycle and up-regulation of the cyclin-dependent kinase inhibitors (CDKI) p21(CIP1/WAF-1/MDA-6) and p27(KIP1). In a nude mouse xenograft model, Ad.PEG.hPNPase(old-35) injections effectively inhibited growth of human pancreatic cancer cells in vivo. These findings support the potential efficacy of combining a cancer-specific promoter, such as the PEG-Prom, with a novel anti-neoplastic agent, such as hPNPase(old-35), to create a potent, targeted cancer therapeutic, especially for a devastating disease like pancreatic cancer.

Pancreatic imaging: current and emerging technologies

This review discusses the current imaging modalities for the diagnosis and staging of solid and cystic pancreatic lesions and for the assessment of acute and chronic pancreatitis, and the future role of emerging technologies in the management of pancreatic diseases. Multidetector row spiral computed tomography is superior to conventional single-detector row spiral computed tomography in the detection and staging of pancreatic adenocarcinoma. Positron emission tomography is a sensitive but relatively nonspecific diagnostic modality. Positron emission tomography-computed tomography fusion may improve the staging accuracy for pancreatic cancer. Echo-enhanced ultrasound may have an emerging role in evaluating pancreatic masses. Endoscopic ultrasound with fine needle aspiration for cytology is the single best method for diagnosis and staging of nonmetastatic pancreatic cancer with a high accuracy for determining tumor resectability. In acute pancreatitis, a modification of the standard computed tomography severity index, which places greater emphasis on extrapancreatic complications, has shown superior correlation with various patient outcome measures. Endoscopic retrograde cholangiopancreatography is still the test of choice for morphological evaluation of chronic pancreatitis, whereas magnetic resonance cholangiopancreatography offers a noninvasive alternative in selected patients. Endoscopic ultrasound can be useful for detecting early chronic pancreatitis. Secretin-stimulated imaging techniques may eventually provide a noninvasive method of reliably assessing pancreatic exocrine function.

Refining the role of laparoscopy and laparoscopic ultrasound in the staging of presumed pancreatic head and ampullary tumours

Laparoscopy and laparoscopic ultrasound have been validated previously as staging tools for pancreatic cancer. The aim of this study was to identify if assessment of vascular involvement with abdominal computed tomography (CT) would allow refinement of the selection criteria for laparoscopy and laparoscopic ultrasound (LUS). The details of patients staged with LUS and abdominal CT were obtained from the unit's pancreatic cancer database. A CT grade (O, A-F) of vascular involvement was recorded by a single radiologist. Of 152 patients, who underwent a LUS, 56 (37%) had unresectable disease. Three of 26 (12%) patients with CT grade O, 27 of 88 (31%) patients with CT grade A to D, 17 of 29 (59%) patients with CT grade E and all nine patients with CT grade F were found to have unresectable disease. In all, 24% of patients with tumours <3 cm were found to have unresectable disease. In those patients with tumours considered unresectable, local vascular involvement was found in 56% of patients and vascular involvement with metastatic disease in 17%, while 20% of patients had liver metastases alone and 5% had isolated peritoneal metastases. The remaining patient was deemed unfit for resection. Selective use of laparoscopic ultrasound is indicated in the staging of periampullary tumours with CT grades A to D.

Magnetic Resonance Imaging of the Pancreas at 3.0 Tesla

OBJECTIVES

We sought to perform a preliminary comparison of signal-to-noise ratio (SNR) and image quality for magnetic resonance imaging (MRI) of the pancreas at 1.5 and 3 T.

MATERIALS AND METHODS

Two imaging cohorts were studied using a T2-weighted, single-shot fast spin-echo pulse sequence and a T1-weighted, fat-suppressed 3D gradient-echo pulse sequence. In the first cohort, 4 subjects were imaged using identical imaging parameters before and after contrast administration at 1.5 and 3.0 T. The SNR was quantified for the pancreas as well as for the liver, spleen, and muscle. In a second cohort of 12 subjects in whom the receiver bandwidth was adjusted for field strength, SNR measurements and qualitative rankings of image quality were performed.

RESULTS

In the study cohort using identical imaging parameters at both magnetic field strengths, the mean (SD) ratios of SNR at 3.0 to 1.5 T of the single-shot fast spin-echo images for the pancreas, liver, spleen, and muscle were 1.63 (0.39), 1.82 (0.39), 1.45 (0.18), 2.01 (0.16), respectively. For the precontrast fat-suppressed 3D gradient-echo sequence, the corresponding ratios were 1.28 (0.29), 1.26 (0.30), 1.16 (0.27), and 1.76 (0.45), respectively; for the arterial phase, the corresponding ratios were 2.02 (0.28), 1.60 (0.42), 1.47 (0.26), and 1.94 (0.32), respectively; and for the delayed postcontrast phase, the corresponding ratios were 1.63 (0.51), 2.01 (0.25), 1.66 (0.06), and 2.31 (0.47), respectively. The SNR benefit of 3.0 T was significantly greater on contrast-enhanced as compared with noncontrast T1-weighted 3D gradient-echo images. In the second study cohort, SNR was superior at 3.0 T, although the use of a reduced readout bandwidth at 1.5 T substantially diminished the advantage of the higher field system. With qualitative comparison of images obtained at the 2 magnetic field strengths, the fat-suppressed 3D gradient-echo images obtained at 3.0 T were preferred, whereas the single shot fast spin-echo images obtained at 1.5 T were preferred because of better signal homogeneity.

CONCLUSIONS

Our results in a small cohort of volunteers and patients demonstrate a marked improvement in SNR at 3.0 T compared with 1.5 T (by a factor of 2 in some cases) when identical imaging parameters were used. The SNR advantage at 3.0 T is diminished but persists when the receiver bandwidth is adjusted for magnetic field strength. The results suggest that 3.0 T may offer promise for improved body MRI, although further technical development to optimize SNR and improve signal homogeneity will be needed before its full potential can be achieved.

Probabilistic reporting of EUS-FNA cytology

BACKGROUND

The objectives of this study were to determine threshold probabilities needed to perform endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) and those needed to treat patients suspected of having malignancy and then to compare these thresholds to the pre- and posttest probabilities of malignancy associated with benign, atypical, suspicious, and malignant diagnoses. The goal was to aid endoscopists in making appropriate clinical decisions based on both quantitative and qualitative approaches.

METHODS

The study included 633 consecutive patients. A decision tree was constructed to estimate the "treatment" threshold. Using treatment threshold and likelihood ratios, the authors determined the "no-test-test" and "test-treatment" thresholds. Pretest probability was compared with no-test-test and test-treatment thresholds, and the post-EUS-FNA probability of malignancy for each diagnostic category with the treatment threshold. Results were stratified by lesion site, lesion size, and cytopathologist.

RESULTS

EUS-FNA has a wide range of pretest probabilities within which it could be performed (0.06-0.98). The posttest probabilities for malignancy, 0.99 (95% confidence interval [CI], 0.967-0.996) and 0.09 (95% CI, 0.057-0.126), after a positive or a negative result, respectively, were significantly different from the treatment threshold but not those of suspicious, 0.92 (95% CI, 0.767-0.994) diagnosis. The posttest probability of atypical diagnosis, 0.60 (95% CI, 0.407-0.772), was not significantly different from that of pretest probability. Results did not vary by lesion size, organ site, or cytopathologist.

CONCLUSION

The authors demonstrated the uncertainty associated with EUS-FNA diagnostic categories and used the threshold approach to qualify quantitatively the decision to perform EUS-FNA and the decision to treat patients suspected of having malignancy.

Molecular targeting of pancreatic disorders

During the last decade significant advances in gene therapy have made it possible to treat various pancreatic disorders in both animal models and in humans. For example, insulin gene delivery to non-beta-cell tissues has been shown to reverse hyperglycemia in diabetic mice, and islet transplantation, based on in vitro differentiation of beta cells and concomitant gene targeting to prevent host autoimmune responses, has become more feasible. Additionally, introduction of the glucokinase regulatory protein and protein kinase C-zeta have been shown to improve glucose tolerance in non-insulin-dependent diabetes mellitus animal models. Pancreatic cancer studies utilize several DNA-based strategies for tumor treatment including introduction of tumor suppressor genes, suppression of oncogenes, suicide gene/prodrug therapy, and restricted replication-competent virus therapy. Tumor-specific targeting is an important part of suicide gene therapy, and tumor-specific promoters are used for cell-specific targeting. Tumor-specific suicide gene therapy directed by the rat insulin promoter has been used to eliminate insulinoma tumors in a mouse model. This review compiles a compendium of information related to the treatment of pancreatic disorders using gene therapy.

Cost-effectiveness Analysis in the Assessment of Diagnostic Imaging Technologies

In many ways, diagnostic technologies differ from therapeutic medical technologies. Perhaps most important, diagnostic technologies do not generally directly affect long-term patient outcomes. Instead, the results of diagnostic tests can influence the care of patients; in that way, diagnostic tests may affect long-term outcomes. Because of this, the benefits associated with the use of a specific diagnostic technology will depend on the performance characteristics (eg, sensitivity and specificity) of the test, as well as other factors, such as prevalence of disease and effectiveness of available treatments for the disease in question. The fact that diagnostic tests affect short-term, or "surrogate," outcomes, rather than long-term patient outcomes makes evaluation of these tests more complicated than the evaluation of therapeutic technologies. This article will trace the history of technology assessment in medicine, address the role of cost-effectiveness and decision analysis in health technology assessment, and describe unique features and approaches to assessing diagnostic technologies. The article will then conclude with a consideration of the limits of medical technology assessment.

Intravenous Delivery of Liposome-mediated Nonviral DNA Is Less Toxic than Intraperitoneal Delivery in Mice

Suicide gene therapy has been shown to be an effective means of destroying pancreatic cancer cells. Liposomes have been described as having better efficacy in gene delivery, and an advantage of using liposomes as gene carriers is that they can be used repeatedly in vivo. The objective of this study is to compare the effect of gene delivery routes and to determine whether systemic delivery of the rat insulin promoter (RIP)-directed suicide gene construct would permit cell-specific gene delivery in vivo. Severe combined immunodeficient (SCID) mice were injected with liposome-RIP-TK (thymidine kinase) complex by either the intraperitoneal or the intravenous route. Twenty-four hours post gene delivery, mice received ganciclovir (GCV) treatment twice daily for 14 days. Mice were sacrificed at various time points. Complete necropsy and serum chemistry analysis were performed. Islet morphology was determined using hematoxylin and eosin (H&E) staining. Serum glucose and insulin levels were also determined. To determine the toxic effect on pancreatic islet cells, immunostaining of insulin-producing and glucagon-producing cells was carried out at each time point. H&E staining indicated that both intravenous and intraperitoneal liposome-RIP-TK gene expression had no effect in normal endocrine islet cells. Both gene-delivery routes in mice resulted in normal glycemia and serum insulin levels. The endocrine islets were intact, with a normal distribution pattern of insulin-producing beta cells and glucagon-secreting alpha cells. However, serum chemistry analysis revealed significantly elevated levels of liver enzymes; suggesting that possible liver damage had occurred with the intraperitoneal gene delivery of liposome-pRIP-TK. Intravenous liposome-mediated gene delivery had no effect on liver enzyme levels. Liposome-mediated gene delivery via intravenous injection was less toxic than intraperitoneal delivery. This gene-delivery route requires fewer liposome-DNA complexes and maintains normal liver function. Thus, intravenous delivery of gene therapy would be superior to intraperitoneal administration of gene therapy in mice.

Does multidetector-row CT eliminate the role of diagnostic laparoscopy in assessing the resectability of pancreatic head adenocarcinoma?

BACKGROUND

We hypothesized that the high-quality images from multidetector-row computed tomography (MDCT) would lead to improved sensitivity and specificity for predicting resectable pancreatic head adenocarcinoma, thus diminishing the value of staging laparoscopy.

METHODS

Forty four consecutive patients underwent thin-section dual-phase MDCT to stage their tumor, followed by an attempted pancreaticoduodenectomy. Four radiologists who were blinded to the operative outcome reviewed the scans and graded the presence of distant and nodal metastases, as well as the degree of arterial and portal involvement. The radiologic criteria for resectability were no distant metastasis, a patent portal vein, and < 50% arterial involvement.

RESULTS

The overall resectability for this cohort was 52% (23/44). The 21 unresectable cases, included five liver metastases, three peritoneal metastases, and 13 locally invasive tumors. The negative margin resection rate was 34% (15/44). There were no portal vein resections. The sensitivity and specificity of MDCT for predicting resectability were 96% (22/23) and 33% (7/21), respectively. In this cohort, the positive and negative predictive values were 61% (22/36) and 87.5% (7/8), respectively. As determined by univariate logistic regression, only the degree of arterial involvement was a significant predictor of resectability (p = 0.02). As determined by multivariate logistic regression using both arterial and portal involvement, arterial involvement was predictive (p = 0.03) but portal vein involvement was not (p = 0.45).

CONCLUSIONS

Despite the improvements in image quality obtained with multidetector-row technology, CT imaging remains a relatively nonspecific test for predicting resectability in patients with adenocarcinoma of the head of the pancreas. Minimally invasive modalities with higher specificity, particularly laparoscopy, continue to have an important role in staging pancreatic head adenocarcinoma.

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.

Imaging of pancreatic adenocarcinoma with emphasis on multidetector CT

Pancreatic adenocarcinoma is the fourth most frequent cause of cancer-related death. The incidence is increasing and the overall survival has altered little in recent years. Moreover, patients usually present late with inoperable disease and curative resection by standard pancreatico-duodenectomy (Whipple's procedure) is associated with significant morbidity. It should only be attempted in that small group of patients lacking radiological evidence of advanced disease. Despite the recent advances in body magnetic resonance imaging (MRI) and endoscopic ultrasound (EUS), computed tomography (CT) is the mainstay of staging in most centres and the recent development of multidetector CT machines (MDCT) has raised hope of an improvement in preoperative staging. This review focuses on the CT of pancreatic adenocarcinoma with particular emphasis on examination technique and on those criteria that determine resectability.

Prospective evaluation of ultrasound and colour duplex imaging for the assessment of surgical resectability of pancreatic tumours

BACKGROUND

This study was performed to evaluate colour duplex imaging (CDI) for the assessment of resectability of pancreatic tumours (PTs).

METHOD

From October 1998 to December 2001, 182 patients consecutively having surgery for a PT were enrolled in this prospective study. Extension of the tumour to large blood vessels and retroperitoneum, the detection of liver metastases, enlarged lymph nodes and peritoneal carcinomatosis were defined as criteria for assessment. The patients were grouped into three classes of resectability: US-TU 1 = resectable/potentially curable, US-TU 2 = questionably resectable/curable, and US-TU 3 = non-resectable/not curable. CDI was performed by five different examiners. Results were compared with intra-operative findings.

RESULTS

Using CDI, we classified 85 (46.7%) tumours as resectable, 64 (35.2%) as non-resectable, and 33 (18.1%) as questionably resectable. Overall, 46.2% ( n=84) were found to be resectable, and 53.8% ( n=98) to be non-resectable, intra-operatively. A correlation between CDI classification and intra-operative findings was found in 138 of 149 cases (92.6%) (sensitivity 88.4%, specificity 96.3%). With regard to the complete oncological status (local extension, metastases, lymph-node staging and peritoneal carcinomatosis), a sensitivity of 77.2% and specificity of 95.7% were found. Non-correlated findings were likely attributed to missing small liver metastases, peritoneal carcinomatosis without ascites, and on difficulties in the assessment of enlarged lymph nodes concerning tumour infiltration.

CONCLUSION

The use of CDI in evaluation of PTs may provide valuable pre-operative assessment of surgical resectability and may be performed in the clinical setting.

Mesenteric neoplasms: CT appearances of primary and secondary tumors and differential diagnosis

Computed tomography (CT) remains the optimal imaging modality for diagnosing tumors in the mesentery. Although primary neoplasms arising from the mesenchymal tissues of the mesentery are rare, the small bowel mesentery is a major avenue for the dissemination of tumor within the peritoneal cavity. Tumors spread to the mesentery by four major routes: (a) direct extension, commonly seen with carcinoid tumor of the small intestine as well as intraabdominal cancers such as pancreatic and colon cancer; (b) lymphatic dissemination of lymphoma and some epithelial malignancies; (c) hematogenic spread resulting in embolic metastases to the small intestinal wall, usually seen in melanoma and breast cancer; and (d) seeding through the peritoneum from ovarian and gastrointestinal malignancies as well as some lymphomas. Although percutaneous imaging-guided or surgical biopsy is often necessary to guide management, analysis of CT features along with the clinical history may be useful in differentiating mesenteric tumors from infectious, inflammatory, or vascular processes affecting the mesentery. The article presents the characteristic appearances of primary and secondary mesenteric neoplasms at CT and offers a rational approach to the differential diagnosis of mesenteric masses depicted at CT.