Circumferential resection margins of rectal tumours post-radiotherapy: how can MRI aid surgical planning?

BACKGROUND: Magnetic resonance imaging (MRI) is known to have high predictive accuracy for circumferential resection margin (CRM) involvement of pre-treatment rectal tumours. This study aims to assess predictive accuracy of MRI for CRM involvement in rectal cancers post-long-course chemoradiotherapy (CRT) and in particular to understand how this information can influence surgical planning. METHODS: Forty-seven rectal cancers treated with CRT followed by bowel resection in one hospital since 2005 were reviewed for clinical, radiological and pathological characteristics. Using a validated pro forma, a radiologist blinded to final histology and original MRI report predicted CRM status from post-CRT MRI images. Results were compared to histological CRM status of final specimen, and differential analysis by type of surgical operation was performed. RESULTS: Overall accuracy of MRI for CRM involvement post-CRT was 72 % with a negative predictive value of 92 %. Abdominoperineal excision (APE) post-CRT was associated with non-significantly higher rates of histologically involved CRM than anterior resection (AR; 41 vs. 21 %) as were mucinous adenocarcinomas when compared to non-mucinous (56 vs. 21 %). Overall accuracy and positive predictive value were non-significantly higher for cancer treated with a standard APE than AR, and negative predictive value was high for both groups. CONCLUSIONS: MRI post-CRT has high negative predictive value for CRM status. Such information is of particular clinical relevance in low rectal cancers treated with APE as it can indicate when a standard surgical approach is likely to be sufficient.

Imaging in bariatric surgery: service set-up, post-operative anatomy and complications.

Obesity is an increasingly prevalent and costly problem faced by the healthcare system. The role of bariatric surgery in managing obesity has also increased with evidence showing a reduction in long-term morbidity and mortality. There are unique challenges faced by the radiology department in providing an imaging service for this population of patients, from technical and staffing requirements through to the interpretation of challenging post-surgical images. We describe these challenges and provide an overview of the most frequently performed procedures, normal post-operative imaging findings and the appearance of common complications.

Immediate and sustained benefits of a "total" implementation of speech recognition reporting.

Speech recognition reporting was introduced in our institution to address the significant delay between report dictation and the appearance of a typed report on the Picture Archiving and Communication System (PACS). We report our experience of a "total" implementation of a speech recognition reporting (SRR) system, which became the sole means of radiology reporting from day 1 of introduction. Prospectively gathered Radiology Information System (RIS) data were examined to determine the monthly mean reporting times and completion times for all studies from January 2004 to February 2006 (11 months before introduction of SRR and 15 months after introduction). Studies were grouped for analysis according to referral source (casualty, general practice, inpatient or outpatient). A large, sustained reduction in time to completion was noted in all referral groups at both hospital sites within our institution (6.79 +/- 0.92 days pre-SRR and 2.20 +/- 0.78 days post-SRR, independent two-sample Student's t-test, p<10(-11)). Workflow was maintained following the introduction of SRR: numbers of reports per month and mean times to report were unchanged. SRR eliminated the delays associated with report transcription and subsequent authorisation, dramatically reducing report turnaround times. Resistance to change has perhaps led to suboptimal implementation of SRR in some other institutions, such that benefits have not been fully realised. Our experience demonstrates the dramatic impact that a well-planned, organisation-wide implementation of SRR can have on radiology service delivery.

Variation of mesorectal volume with abdominal fat volume in patients with rectal carcinoma: assessment with MRI.

The purpose of this study was to assess the variability in the volume of the mesorectum in patients with rectal carcinoma. A retrospective review was made of pelvic MRI studies in 30 patients (mean age 64 years, range 34-88 years, 18M:12F) with histologically proven rectal carcinomas that were confined to the mesorectum. The outer low signal margin of the mesorectum was traced, over at least 10 consecutive 10 mm contiguous slices, until its disappearance. The visceral fascial compartment, body cross-sectional area and body mass index were measured, on a solitary slice, at the level of the L5/S1 disc. Linear regression was calculated for independent determinants of the mesorectal volume. Mean mesorectal volume in males was 227.5 cm3 (95%CI 191.6-263.4), and in females was 157.5 cm3 (95%CI 129.3-185.7). The difference in mesorectal volume between men and women was statistically significant (p<0.001). Mean visceral compartment area in males was 18.4 cm2 (95%CI 16.3-20.5) and in females was 14.6 cm2 (95%CI 12.8-16.4). Visceral compartment area correlated with mesorectal area and volume in females (p<0.05), and extremely well in males (p<0.005). Body cross-sectional area, body mass index and age did not correlate with mesorectal size. The correlation of visceral compartment area with mesorectal volume and mean area suggests that the mesorectum is determined in a similar way to other body fat compartments, with a similar anatomical variation. This significant variation in size and volume may have an important prognostic implication in patients with rectal carcinoma. This volume can be measured and reported on pre-operative MRI scanning and may be communicated to surgeons and radiotherapists.

Radiology of gestational trophoblastic neoplasia.

Gestational trophoblastic neoplasia (GTN) encompasses a broad spectrum of placental lesions from the pre-malignant hydatidiform mole (complete and partial) through to the malignant invasive mole, choriocarcinoma and rare placental site trophoblastic tumour (PSTT). Ultrasound remains the radiological investigation of choice for initial diagnosis, and it can also predict invasive and recurrent disease. Magnetic resonance imaging is of invaluable use in assessing extra-uterine tumour spread, tumour vascularity, and overall staging. Positron emission tomography and computed tomography undoubtedly have a role in recurrent and metastatic disease, while angiography has a place in disease and complication management. This review will describe the relevant pathophysiology and natural history of GTN, and the use of imaging techniques in the diagnosis and management of these conditions.

Airway obstruction: a rare complication of thrombolytic therapy.

Bleeding into head and neck structures as a complication of thrombolysis is extremely rare but potentially lethal. It is usually associated with local trauma. We describe a case of a 67-year-old woman who developed spontaneous, massive pan aerodigestive tract haemorrhage precipitating airway obstruction following administration of streptokinase for myocardial infarction; a previously unreported complication. This case highlights the importance of being vigilant of airway symptoms following such treatment, prompting early involvement of anaesthetic and otolaryngology personnel.

Lethal effects of freezing Echinococcus multilocularis eggs at ultralow temperatures.

Methods for killing Echinococcus multilocularis eggs within stool or intestinal samples, without damaging the diagnostic value of the sample, would significantly reduce the risk of animal health providers acquiring alveolar hydatid disease. The first objective of this study was to determine whether E. multilocularis eggs located in fox intestines can survive storage at -70 C for at least 4 days. Results showed that none of 72,000 E. multilocularis eggs remained infectious to defined strains of mice under these conditions, yet, similar eggs recovered from nonfrozen carcasses stored at 4 C for the same time period were viable. The structural identities of adult worms and eggs were not significantly altered by the freezing and thawing processes. These results indicate that ultracold temperatures can be used to kill or inactivate E. multilocularis eggs, making them safe to handle when diagnosing this parasite in definitive hosts. The second objective of this study was to determine whether E. multilocularis eggs could survive freezing to -70 C if commonly used cryopreservation protocols were used. The use of the cryoprotectant solution, 5% dimethyl sulfoxide-35% saline-60% lamb serum, with a -1 C/min freezing rate was unable to prevent the eggs from being killed by freezing to -70 C. Rapid cooling by plunge freezing into liquid nitrogen was also lethal to E. multilocularis eggs. Only a few of the many potential cryopreservation protocols were tested in this study, so it is not yet possible to completely rule out the possibility of preserving these eggs at ultralow temperatures, but it does indicate that temperatures below -70 C are lethal to eggs even under favorable storage conditions.

Warfarin-associated thoracic aortic dissection in an elderly woman.

BACKGROUND: The risk/benefit ratio of warfarin therapy changes in the over 75s, when haemorrhagic side-effects become more common. These may not always be reported in the literature. CASE REPORT: A woman of 80 years, on long-term warfarin therapy presented with an acute dissecting thoracic aortic aneurysm; on investigation the only precipitating factor found was an international normalised ratio of 4.8. This patient, who also had an abdominal aortic aneurysm, survived, on discontinuation of her anticoagulant therapy. CONCLUSIONS: We describe a previously unreported complication of warfarin therapy in a patient over 75 years of age, to add to the cautions in prescribing this drug in patients of this age group.

Safety and efficacy of PNU-142633, a selective 5-HT1D agonist, in patients with acute migraine.

In this randomized, double-blind, placebo-controlled, parallel-group study, patients received a single 50-mg oral dose of a 5-HT(1D) agonist, PNU-142633 (n = 34), or matching placebo (n = 35) during an acute migraine attack. No statistically significant treatment effects were observed at 1 and 2 h after dosing, even after stratifying by baseline headache intensity. At 1 and 2 h post-dose, 8.8% and 29.4% of the PNU-142633 group, respectively, and 8.6% and 40.0% of the placebo group, respectively, experienced headache relief; 2.9% and 8.8% of the PNU-142633 group and 0% and 5.7% of the placebo group were free of headache pain. Adverse events associated with PNU-142633 treatment included chest pain (two patients) and QTc prolongation (three patients). Results from this study suggest that anti-migraine efficacy is not mediated solely through the 5-HT(1D) receptor subtype, although this receptor may contribute, at least in part, to the adverse cardiovascular effects observed with 5-HT agonist medications.

Evaluation of the role of pre-operative magnetic resonance imaging in the management of rectal cancer.

OBJECTIVES: This study assesses the ability of body coil magnetic resonance imaging (MRI) to pre-operatively stage mural penetration, nodal status and circumferential resection margin (CRM) involvement of rectal cancer. PATIENTS AND METHODS: Between 1995 and 1997, MRI using a body coil was performed in consecutive patients with primary rectal carcinomas. Group A: 67 patients underwent surgery without long course neo-adjuvant therapy. Predicted tumour stage was compared to the histology of the specimen. Group B: 21 patients with MRI evidence of advanced disease, underwent long course neo-adjuvant therapy followed by repeat MRI prior to surgery. The second scan assessed response to treatment and likelihood of CRM involvement at subsequent surgery. RESULTS: Group A: Accuracy of pre-operative staging was: 'T' stage - 54%, 'N' stage - 77%, involvement of CRM by tumour - 97%. Group B: After long course neo-adjuvant therapy the second MRI scan was 95% accurate in predicting CRM involvement by tumour. CONCLUSION: In this study pre-operative rectal cancer staging with MRI and a body coil lacks accuracy in predicting mural penetration and nodal involvement. Body coil MRI can accurately predict the potential for CRM involvement. This technique may help determine which patients require long course neo-adjuvant therapy.

Inhibition of selenite cataract by S-diethylsuccinyl glutathione isopropyl ester.

PURPOSE: Previous studies have demonstrated that glutathione derivatives can partially prevent loss of hepatic glutathione levels, in vivo, during periods of oxidative stress. Since cataracts in animal model systems and in humans are thought to be the direct result of oxidative insult, the following study tested the possibility that treatment with these glutathione analogues may affect the progression of lens opacification. METHODS: Glutathione esters were tested for their ability to inhibit the selenite-induced cataract in rats. RESULTS: The S-alkyl glutathione ester Et(2)Sc-GS-iPr, but not a similar glutathione derivative S-succinyl glutathione (Sc-GS), at 0.5 mmoles/kg body weight, had anti-cataract activity in the selenite-induced cataract of rats. Analysis of lenses from treated and untreated animals demonstrated that Et(2)Sc-GS-iPr partially prevented the loss of reduced glutathione levels. CONCLUSIONS: The results demonstrate for the first time that an S-alkylated glutathione ester has anti-cataractogenic potential in the selenite-treated rat, and suggest possible mechanisms involving glutathione in the prevention of this lens opacification.

High-throughput SNP detection by using DNA pooling and denaturing high performance liquid chromatography (DHPLC).

One of the critical steps in the positional cloning of a complex disease gene involves association analysis between a phenotype and a set of densely spaced diallelic markers, typically single nucleotide repeats (SNPs), covering the region of interest. However, the effort and cost of detecting sufficient numbers of SNPs across relatively large physical distances represents a significant rate-limiting step. We have explored DNA pooling, in conjunction with denaturing high performance liquid chromatography (DHPLC), as a possible strategy for augmenting the efficiency, economy, and throughput of SNP detection. DHPLC is traditionally used to detect variants in polymerase chain reaction products containing both allelic forms of a polymorphism (e.g., heterozygotes or a 1:1 mix of both alleles) via heteroduplex separation and thereby requires separate analyses of multiple individual test samples. We have adapted this technology to identify variants in pooled DNA. To evaluate the utility and sensitivity of this approach, we constructed DNA pools comprised of 20 previously genotyped individuals with a frequency representation of 0%-50% for the variant allele. Mutation detection was performed by using temperature-modulated heteroduplex formation/DHPLC and dye-terminator sequencing. Using DHPLC, we could consistently detect SNPs at lower than 5% frequency, corresponding to the detection of one variant allele in a pool of 20 alleles. In contrast, fluorescent sequencing detected variants in the same pools only if the frequency of the less common allele was at least 10%. We conclude that DNA pooling of samples for DHPLC analysis is an effective way to increase throughput efficiency of SNP detection.

Effect of combined administration of insulin-like growth factor and platelet-derived growth factor on the regeneration of transected and anastomosed sciatic nerve in rats.

OBJECTIVE: To evaluate the efficacy of combined administration of platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF-I) on the regeneration of transected and anastomosed sciatic nerves. ANIMALS: 25 male Lewis rats. PROCEDURE: Transection and anastomosis was performed of the left sciatic nerve of all rats. At the time of surgery, treatment group rats received a combination of PDGF (0.75 microgram) and IGF-I (1.5 micrograms) along with vehicle (2% methyl cellulose gel) at the anastomosis site. Control rats received vehicle alone. Evaluation consisted of motor evoked potentials and nerve conduction velocity, quantitative histologic examination, sciatic functional index, and visual assessment of repair organization (lesion scores). RESULTS: Significant differences in motor evoked potential latency, nerve conduction velocity, axon number, sciatic functional index, or lesion scores were not found between groups. CONCLUSIONS: Combined administration of PDGF and IGF-I did not enhance peripheral nerve regeneration in a transection and anastomosis model as determined 6 weeks after surgery. CLINICAL RELEVANCE: These findings support the assumption that mechanical, versus trophic, effects predominate when nerve ends are closely apposed.