The role of dual time point FDG PET imaging in the evaluation of solitary pulmonary nodules with an initial standard uptake value less than 2.5

AIM

To evaluate the accuracy of dual time point 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET) imaging in the evaluation of the mildly metabolic solitary pulmonary nodule (SPN) and to assess whether accuracy could be improved by delaying second image acquisition to 180 minutes.

MATERIALS AND METHODS

Fifty-four patients were included in the study. Thirty-six had an SUV(max) <2.5 at 60 min. For these patients, two methods of interpreting the subsequent delayed FDG PET imaging at 180 min were investigated. The first method analysed the SUV(max) of SPNs on delayed imaging, in which an SUV(max) of 2.5 or more was regarded as a criterion for malignancy. The second method was retention index (RI) analysis, in which an increase of 10% or more in SUV(max) between the initial and delayed images, was regarded as an indication of malignancy.

RESULTS

For the group as a whole (n=54), the sensitivity, specificity and accuracy of using an SUV(max) of 2.5 or more as an indication of malignancy at the time of initial image acquisition (60 min) was 58, 89, and 74%, respectively. For SPNs that had an initial SUV(max) <2.5 (n=36), the sensitivity, specificity, and accuracy of using an SUV(max) of 2.5 or more as a criterion for malignancy on the delayed image acquisition (180 min), was 36, 96, and 78% respectively. However, if an RI of >10% was used as a criterion for malignancy between the initial and delayed images, the sensitivity, specificity, and accuracy was 73, 80, and 78%, respectively. These results are similar to a recent paper, where image acquisition occurred at 60 and 120 min post-tracer injection.

CONCLUSION

Dual time point FDG PET imaging with RI analysis, is a useful technique in evaluating SPN with an initial SUV(max) <2.5. Prolonging second image acquisition from 120 to 180 min does not appear to improve the accuracy of this technique. However, given that maximal FDG uptake by lung carcinomas is thought to be in the region of 5h, it may be that improving the accuracy of dual time point FDG PET imaging requires a more significant delay in second image acquisition in this specific subgroup.

Non-invasive prediction of the degree of liver fibrosis in patients with hepatitis C using an ultrasound contrast agent. A pilot study

It has been shown that the severity of hepatic fibrosis in patients with hepatitis C can be predicted non-invasively by measuring intrahepatic circulatory time (IHCT) using a microbubble agent with spectral Doppler analysis. The aim of this study was to assess whether this technique is reproducible using a third-generation microbubble agent and contrast harmonic imaging, which are becoming the standard ultrasound techniques in all radiology departments. Twenty-three untreated patients with hepatitis C, who had undergone a recent liver biopsy, were studied prospectively. Based on their histological fibrosis score, patients were divided into four groups (fibrosis levels 1-4). Contrast harmonic imaging was carried out after an intravenous bolus of a microbubble agent (Optison; Amersham Health, Milwaukee, WI, USA). IHCT was calculated by measuring the difference between the hepatic vein and hepatic artery microbubble arrival times. The IHCT was compared with the degree of fibrosis. Significant differences were shown between the groups for IHCT. There were significant differences between fibrosis levels 1 and 3 and between fibrosis levels 1 and 4. This study has shown that calculation of IHCT using a third-generation microbubble agent and contrast harmonic imaging can differentiate mild fibrosis from more severe degrees of fibrosis in patients with hepatitis C.

Evidence-based obstetrics in Australia: can we put away the wooden spoon?

In the evidence-based medicine stakes, obstetrics has risen from being the holder of the "wooden spoon" to being a world leader in the pursuit of best evidence and the use of formal systematic reviews. A prime example of evidence-based obstetric practice is the use of corticosteroids to reduce respiratory distress syndrome in preterm infants. However, in other areas, such as the rising caesarean section rates, providing best evidence to guide practice has proven difficult. The availability of evidence has not always resulted in changed clinical practice and improved patient care. Researchers in Australia are now examining strategies to maximise dissemination of available best evidence into obstetric practice. Without reflective practice and effective dissemination of evidence, the present litigation phobia surrounding obstetric care could lead to evidence-based medicine being replaced by "nervousness-based medicine".

Hyperplastic polyposis: association with colorectal cancer

Hyperplastic polyposis is a loosely defined syndrome initially thought not to confer a clinically important predisposition to colorectal cancer. The aim of the current study was to examine the clinical, histologic, and molecular features of a prospective series of cases meeting a strict definition of the condition. Twelve patients were identified, seven of whom had developed colorectal cancer. Most polyps were hyperplastic, but 11 patients also had polyps containing dysplasia as either serrated adenomas. mixed polyps, or traditional adenomas. The mean percentage of dysplastic polyps in patients with cancer was 35%, and in patients without cancer, 11% (p < 0.05). Microsatellite instability (MSI) was present in 3 of 47 hyperplastic polyps and two of eight serrated adenomas. Kras was mutated in 8 of 47 hyperplastic polyps and two of eight serrated adenomas. No polyps showed loss of heterozygosity of chromosomes 5q, 1p, or 18q. Two of seven cancers showed a high level of MSI. It is concluded that hyperplastic polyposis is associated with a high risk of colorectal cancer. Hyperplastic polyps are the dominant type of polyp, but most cases have some dysplastic epithelium. A higher proportion of dysplastic polyps is associated with increased cancer risk. Clonal genetic changes are observed in some hyperplastic polyps and serrated adenomas.

[C-reactive protein as an independent marker of prognosis in acute coronary syndrome: comparison with troponin T]

BACKGROUND

It has been suggested that inflammatory processes play a role in the pathogenesis of acute coronary syndromes (ACS). C-reactive protein (CRP) is a classic acute phase protein. It is yet unclear whether, in addition to established markers as troponin T (TnT), determination of CRP in patients admitted for ACS contributes significantly to the diagnosis and prognosis of ACS.

PATIENTS AND METHODS

We investigated 50 patients with ACS (59.4 SD 13.9 years) in the first hour after admission and 4-24 h later with respect to TnT (Elecsys, Roche Diagnostics) and CRP (biokit, modified Quantex CRP plus, analytical sensitivity 0.02 mg/dL). Fifty percent of the patients were classified as having unstable angina retrospectively. All patients were followed in the 6 weeks post discharge regarding death and recurrent ACS.

RESULTS

The cumulative event rate at 6 weeks after discharge was 62.5% for patients being CRP and TnT positive compared to 35.3% in TnT positive and CRP negative patients. In TnT negative patients a positive CRP test predicted 33.3% of events and 28.8% of patients negative for CRP and TnT had events at 42 days post discharge. Logistic regression analysis regarding the primary endpoint including TnT and CRP (4-24 h values), age, gender and diagnosis resulted in independent prediction of ACS or death by TnT (cutoff 0.1 microgram/L, p = 0.048, odds ratio = 7.5) and CRP (cutoff 0.862 mg/dL, p = 0.026, odds ratio = 5.3). Sensitivity/specificity for AMI diagnosis were 69.6%/75% for TnT and 12%/72% for CRP in the first hour and 91.3%/68.2% for TnT and 68%/72% for CRP 4-24 h later.

CONCLUSIONS

Besides TnT, high sensitivity CRP determination has no additional value for early AMI diagnosis. The prognosis of these patients during the first 24 hours is significantly and independently predicted by CRP measurements in addition to troponin T.

Fulminant tracheobronchial and pulmonary aspergillosis complicating imported Plasmodium falciparum malaria in an apparently immunocompetent woman

We describe an unusual case of fulminant tracheobronchial and pulmonary aspergillosis presenting as acute respiratory distress syndrome. The patient, who was apparently immunocompetent, was admitted with severe Plasmodium falciparum malaria but died from aspergillosis.

Defining competency - the role of standard setting

CONTEXT

The responsibility to determine just who is competent to practice medicine, and at what standard, is great. Whilst there is still a period available for potential remediation, examinations at the completion of year three of the four-year Graduate Entry Medical Programme (GEMP) at Flinders University of South Australia (FUSA) are high stakes and contain the majority of final summative assessment for the certification of student to doctor. Therefore, the medical school has recently examined its methods for certification, the clinical practice standards sought in its programme and how to determine these standards.

DESIGN

For all assessments a standard was documented and methods employed to set these standards using specific measures of performance. A modification of the Angoff method was applied to the written examination and the Rothman method, using two criteria, was used to determine competency in the objective structured clinical examination (OSCE). These methods were used for the first time in 1998. Both methods used trained 'experts' as standard setters and both methods used the notion of the 'borderline candidate' to determine the passing standard. This paper describes these two criterion-referenced standard-setting procedures as used in this school and related examination performance.

CONCLUSIONS

Whilst the use of standard-setting procedures goes part way to defining and measuring competence, it is time consuming and requires significant examiner training and acceptance. Using 50% to determine who is and isn't competent is simpler but not transparent, fair nor defensible.

Characterisation of a subtype of colorectal cancer combining features of the suppressor and mild mutator pathways

BACKGROUND

10% of sporadic colorectal cancers are characterised by a low level of microsatellite instability (MSI-L). These are not thought to differ substantially from microsatelite-stable (MSS) cancers, but MSI-L and MSS cancers are distinguished clinicopathologically and in their spectrum of genetic alterations from cancers showing high level microsatellite instability (MSI-H).

AIMS

To study the distribution of molecular alterations in a series of colorectal cancers stratified by DNA microsatellite instability.

METHODS

A subset of an unselected series of colorectal cancers was grouped by the finding of DNA MSI at 0 loci (MSS) (n = 51), 1-2 loci (MSI-L) (n = 38) and 3-6 loci (MSI-H) (n = 25). The frequency of K-ras mutation, loss of heterozygosity (LOH) at 5q, 17p and 18q, and patterns of p53 and beta catenin immunohistochemistry was determined in the three groups.

RESULTS

MSI-H cancers had a low frequency of K-ras mutation (7%), LOH on chromosomes 5q (0%), 17p (0%) and 18q (12.5%), and a normal pattern of immunostaining for p53 and beta catenin. MSI-L cancers differed from MSS cancers in terms of a higher frequency of K-ras mutation (54% v 27%) (p = 0.01) and lower frequency of 5q LOH (23% v 48%) (p = 0.047). Whereas aberrant beta catenin expression and 5q LOH were concordant (both present or both absent) in 57% of MSS cancers, concordance was observed in only 20% of MSI-L cancers (p = 0.01).

CONCLUSIONS

MSI-L colorectal cancers are distinct from both MSI-H and MSS cancers. This subset combines features of the suppressor and mutator pathways, may be more dependent on K-ras than on the APC gene in the early stages of neoplastic evolution, and a proportion may be related histogenetically to the serrated (hyperplastic) polyp.

Expression of Bcl-2 protein is decreased in colorectal adenocarcinomas with microsatellite instability

Bcl-2 is known to inhibit apoptosis and is thought to play a role in colorectal tumour development. Studies of the promoter region of bcl-2 have indicated the presence of a p53 responsive element which downregulates bcl-2 expression. Since p53 is commonly mutated in colorectal cancers, but rarely in those tumours showing microsatellite instability (MSI), the aim of this study was to examine the relationship of bcl-2 protein expression to MSI, as well as to other clinicopathological and molecular variables, in colorectal adenocarcinomas. Expression of bcl-2 was analysed by immunohistochemistry in 71 colorectal cancers which had been previously assigned to three classes depending upon their levels of MSI. MSI-high tumours demonstrated instability in three or more of six microsatellite markers tested, MSI-low tumours in one or two of six, and MSI-null in none of six. Bcl-2 expression in tumours was quantified independently by two pathologists and assigned to one of five categories, with respect to the number of cells which showed positive staining: 0, up to 5%; 1, 6-25%; 2, 26-50%; 3, 51-75%; and 4, > or =76%. Bcl-2 negative tumours were defined as those with a score of 0. Bcl-2 protein expression was tested for association with clinicopathological stage, differentiation level, tumour site, age, sex, survival, evidence of p53 inactivation and MSI level. A significant association was found between bcl-2 expression and patient survival (P = 0.012, Gehan Wilcoxon test). Further, a significant reciprocal relationship was found between bcl-2 expression and the presence of MSI (P = 0.012, Wilcoxon rank sum test). We conclude that bcl-2 expressing colorectal cancers are more likely to be MSI-null, and to be associated with improved patient survival.

Morphology of sporadic colorectal cancer with DNA replication errors

BACKGROUND

Up to 15% of colorectal cancers are characterised by DNA microsatellite instability (MIN), shown by the presence of DNA replication errors (RERs).

AIMS

To identify pathological features that are discriminating for colorectal cancer (CRC) showing extensive MIN.

SUBJECTS

A prospective series of 303 patients with CRC and no family history of either familial adenomatous polyposis or hereditary non-polyposis colorectal cancer.

METHODS

DNA was extracted from fresh tissue samples and the presence of MIN was studied at nine loci that included TGF beta RII, IGFIIR, and BAX. The 61 cases showing RERs were compared with 63 RER negative cases with respect to a comprehensive set of clinical and pathological variables. Predictive utility of the variables was tested by decision tree analysis.

RESULTS

Twenty seven patients with CRC showed extensive RERs (three loci or more) (RER+) and 34 had limited RERs only (28 = one locus; 6 = two loci) (RER+/-), yielding a bimodal distribution. RER+ cancers differed from RER- and RER+/-) cases. Tumour type (adenocarcinoma, mucinous carcinoma, and undifferentiated carcinoma) (p = 0.001), tumour infiltrating lymphocytes (p = 0.001), and anatomical site (p = 0.001) were the most significant of the discriminating variables. Algorithms developed by decision tree analysis allowed cases to be assigned to RER+ versus RER- and +/- status with a global sensitivity of 81.5%, specificity of 96%, and overall accuracy of 93%.

CONCLUSIONS

Pathological examination of CRC allows assignment of RER+ status; assignment is specific and relatively sensitive. Conversely RER- and RER+/- CRC are indistinguishable.

Deviation of the path of a sliding object due to road camber

After a road accident, slide marks are sometimes seen to exhibit a slight curvature, which is often due to road camber. The lateral deviation from that cause is shown to be the length of the slide multiplied by the lateral gradient and divided by twice the friction coefficient.

Routine antenatal screening: not a case of informed choice

Traditional epidemiological criteria are inadequate for comprehensively evaluating screening activities to identify best practice. In 1995, a study of women in the postnatal period at a major metropolitan teaching hospital in Victoria was conducted to assess, through their perspectives, the role of other factors of significance for the evaluation of routine antenatal screening. In particular, the role of informed choice was examined. The study involved a survey of 376 women and 21 semistructured interviews. The study found that, with an 'opt-out' or routine system of screening, high rates of use were achieved at the expense of informed choice for some participants. In addition, disturbing differences in information delivery and information perception were found between public and private patients. The need for new criteria to identify what constitutes best practice in the delivery of antenatal screening programs is discussed. These criteria should incorporate consideration of broader social and ethical implications for women receiving antenatal screening.

Characteristics of metachronous colorectal carcinoma occurring despite colonoscopic surveillance

PURPOSE

Metachronous colorectal cancer still occurs in a small percentage of patients, despite colonoscopic surveillance. Cancers in hereditary nonpolyposis colorectal cancer for which there is a high risk of metachronous cancer show distinctive DNA changes termed replication errors (RER+). Ten to 20 percent of sporadic colorectal cancers are also RER+. The aim of this study was to identify factors predictive of metachronous colorectal cancer, despite colonoscopic surveillance. Clinicopathologic characteristics and RER status of cancers were examined.

METHODS

Colorectal cancer patients, who entered into a surveillance program of being examined with colonoscopy within six months of surgery and then at intervals of three years thereafter, were reviewed. The 433 patients compliant with the protocol who had had more than one colonoscopy had been followed up for a mean of 3.8 +/- 2.2 years. DNA was extracted from archival paraffin-embedded cancer tissue for determination of RER status.

RESULTS

Ten cases of metachronous cancer were identified, giving a rate of 0.61 percent per year. The site of the index cancer in patients who later developed metachronous cancer was predominantly proximal (P = 0.0007), and these cancers were more likely to have mucinous histology (P < 0.0005). Three of 10 (30 percent) index cancers were RER+, which was not significantly different from unselected series of control colorectal cancers in which 20 of 108 (18.5 percent) were RER+.

DISCUSSION

This study documents the rate of metachronous cancer among patients compliant with a defined colonoscopic screening program and suggests that the risk is highest in patients with a proximal mucinous cancer. RER status does not appear to be a very strong predictive factor, and this study does not support its use as a guide to the frequency of surveillance colonoscopy. More data would be required to determine if RER positivity conferred a relative risk of 3.3 or less.

Frequency of mutation and deletion of the tumor suppressor gene CDKN2A (MTS1/p16) in hepatocellular carcinoma from an Australian population

The tumor suppressor gene CDKN2A (MTS1/p16), located on chromosome 9p21, is inactivated in a variety of tumors including melanomas and tumors of the biliary tract, pancreas, and stomach. The aim of the present study was to determine whether this gene is inactivated in hepatocellular carcinoma (HCC). Twenty-three primary HCCs and four HCC cell lines were examined. Loss of heterozygosity (LOH) analysis was performed using eight polymorphic markers immediately surrounding CDKN2A, and showed a contiguous region of loss, with the two most commonly deleted markers being D9S1604, located between the p16 and p15 genes, at which 7 of 13 informative tumors (54%) showed loss, and D9S171, with 4 of 14 LOH (29%). Exons 1, 2, and 3 of CDKN2A were amplified by polymerase chain reaction to detect homozygous deletions, and single-strand conformation polymorphism (SSCP) analysis was performed to screen for mutations. No homozygous deletions were detected in any sample. SSCP and sequence analysis showed the same nucleotide change at codon 148 in four tumors. This has been reported elsewhere as a polymorphism. One of these four tumors also contained a mutation at codon 119, resulting in the substitution of an acidic amino acid for a basic one. It is concluded that CDKN2A is infrequently deleted or mutated in HCC. The region of allelic loss upstream from CDKN2A might result in inactivation of regulatory sequences important in the expression of this gene; alternatively, a second tumor suppressor gene may be present in the region 9p21-22, proximal to CDKN2A. These possibilities require further investigation.

Autologous fat injection into the vocal folds: technical considerations and long-term follow-up

Numerous materials have been used over the years for vocal fold augmentation. Early use of bioreactive compounds, such as paraffin, gave way to relatively inert substances, such as Teflon. More recently biocompatible materials, such as collagen and autologous fat, have gained wider acceptance. Autologous fat, in particular, is an easily obtainable source for potential rehabilitation of scarred, paralytic, and atrophic vocal folds. However, long-term systematic follow-up has been lacking. Since 1991 we at the University of Kansas Center for Voice and Swallowing Disorders have employed autologous fat for vocal fold augmentation, primarily for either paralysis or repair of a volume-deficient vocal fold segment. Twenty-two patients have completed > or = 1 year of follow-up studies, including graded video-laryngostroboscopy, electroglottography, computerized acoustic analysis, and blinded perceptual analysis by two speech-language pathologists. Statistically significant improvement was demonstrated in many parameters tested, frequently improving with time. Although the volume-deficient group had more "normal" values, the paralysis group had greater improvement in many variables using fat injection. We conclude that while autologous fat injections of the vocal fold may have long-term benefits, certain technical considerations and criteria of selection of patients are critical for success.

Analysis of loss of heterozygosity and KRAS2 mutations in ovarian neoplasms: clinicopathological correlations

The molecular events that give rise to ovarian epithelial neoplasms are not well understood. In particular, it is not known whether adenocarcinomas arise from benign or low malignant potential (LMP) precursors. We have examined a large series of benign (25) and LMP (31) ovarian tumors for loss of heterozygosity (LOH) at multiple loci on 17 chromosomes. LOH was observed in benign tumors on chromosomes 6 (14%) and 9 (5%) and on the X chromosome (33%) only. LOH on these chromosomes was also detected in a small number of LMP neoplasms, suggesting that these may derive sometimes from benign precursors. In addition, we examined LOH in 93 adenocarcinomas. Analysis of associations between LOH events showed that LOH on chromosomes 5 and 17 (P = 0.0002) and on chromosomes 17 and 18 (P = 0.00007) were associated significantly with each other, which suggests that these may represent cooperative, progressive events. No novel significant associations were identified between LOH events and stage, grade, or histology, which would indicate the existence of genetic heterogeneity in ovarian neoplasms. KRAS2 mutations were detected more often in LMP neoplasms than in malignant tumors (P = 0.004) and were detected more often in Stage I/II malignant tumors than in Stage III/IV malignant tumors (P = 0.033), suggesting that LMP tumors with KRAS2 mutations are unlikely to progress to frank malignancy. Univariate (but not multivariate) survival analysis showed that LOH of chromosomes 11 (P = 0.039) and 17 (P = 0.04) was associated with a significantly worse prognosis. Replication of these novel findings is necessary, and the identification, isolation, and characterization of the critical genes affected by LOH will determine their importance in the pathogenesis of ovarian malignancies.

Fearing the worst--why do pregnant women feel 'at risk'?

Whilst pregnancy and childbirth are generally regarded as a joyful and exciting time in a woman's life they are also filled with fear, uncertainty, a feeling of being 'at risk' and anxieties about what the pregnancy and future may hold. In a society where the perinatal and maternal mortality and morbidity rates are low, where do these fears and uncertainties arise from? Why do pregnant women fear the worst? What are the implications of this? A cross-sectional and qualitative study of 376 postnatal women in a major public teaching hospital in Melbourne was undertaken in 1995 to explore women's beliefs and fears about pregnancy and birthing outcomes, through their perceptions and use of routine antenatal screening tests. Through women's perceptions about the value of, and expectations of, routine antenatal screening tests, and their fears during pregnancy, the author explores the 'notion of risk' as perceived by these women.

Transformation of the plant pathogenic fungus, Rhynchosporium secalis

The barley leaf scald fungus, Rhynchosporium secalis, was transformed to hygromycin-B and phleomycin resistance using the hph gene from E. coli and the ble gene from Streptoalloteichus hindustanus under the control of Aspergillus nidulans promoter and terminator sequences. Plasmid DNA was introduced into fungal protoplasts by PEG/CaCl2 treatment. Transformation frequencies varied from 59 to 493 transformants per 10 microg of DNA and 5 x 10(7) protoplasts. The antibiotic-resistant phenotype appeared to be stable under selective, as well as under non-selective, conditions for several generations. Co-transformation using the E. coli uidA gene under the control of A. nidulans promoter and terminator sequences on a non-selectable plasmid occurred at frequencies of up to 66%.

Hepatic iron deposition in human disease and animal models

Iron deposition occurs in parenchymal cells of the liver in two major defects in human subjects (i) in primary iron overload (genetic haemochromatosis) and (ii) secondary to anaemias in which erythropolesis is increased (thalassaemia). Transfusional iron overload results in excessive storage primarily in cells of the reticule endothelial system. The storage patterns in these situations are quite characteristic. Excessive iron storage, particularly in parenchymal cells eventually results in fibrosis and cirrhosis. There is no animal model or iron overload which completely mimics genetics haemochromatosis but dietary iron loading with carbonyl iron or ferrocene does produce excessive parenchymal iron stores in the rat. Such models have been used to study iron toxicity and the action of iron chelators in the effective removal of excessive iron stores.