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Biomedical subjects

D E Malone

Publications and source records attributed to D E Malone.

At least 19 recordsLinked to original sources
PubMed2004

Minimal preparation computed tomography instead of barium enema/colonoscopy for suspected colon cancer in frail elderly patients: an outcome analysis study.

AIM: To evaluate the efficacy of minimal preparation computed tomography (MPCT) in diagnosing clinically significant colonic tumours in frail, elderly patients. MATERIALS AND METHODS: A prospective study was performed in a group of consecutively referred, frail, elderly patients with symptoms or signs of anaemia, pain, rectal bleeding or weight loss. The MPCT protocol consisted of 1.5 l Gastrografin 1% diluted with sterile water administered during the 48 h before the procedure with no bowel preparation or administration of intravenous contrast medium. Eight millimetre contiguous scans through the abdomen and pelvis were performed. The scans were double-reported by two gastrointestinal radiologists as showing definite (>90% certain), probable (50-90% certain), possible (<50% certain) neoplasm or normal. Where observers disagreed the more pessimistic of the two reports was accepted. The gold standard was clinical outcome at 1 year with positive end-points defined as (1) histological confirmation of CRC, (2) clinical presentation consistent with CRC without histological confirmation if the patient was too unwell for biopsy/surgery, and (3) death directly attributable to colorectal carcinoma (CRC) with/without post-mortem confirmation. Negative end-points were defined as patients with no clinical, radiological or post-mortem findings of CRC. Patients were followed for 1 year or until one of the above end-points were met. RESULTS: Seventy-two patients were included (mean age 81; range 62-93). One-year follow-up was completed in 94.4% (n=68). Mortality from all causes was 33% (n=24). Five histologically proven tumours were diagnosed with CT and there were two probable false-negatives. Results were analysed twice: assuming all CT lesions test positive and considering "possible" lesions test negative [brackets] (95% confidence intervals): sensitivity 0.88 (0.47-1.0) [0.75 (0.35-0.97)], specificity 0.47 (0.34-0.6) [0.87 (0.75-0.94)], positive predictive value 0.18 [0.43], negative predictive value 0.97 [0.96], positive likelihood ratio result 1.6 [5.63], negative likelihood ratio result 0.27 [0.29], kappa 0.31 [0.43]. Tumour prevalence was 12%. A graph of conditional probabilities was generated and analysed. A variety of unsuspected pathology was also found in this series of patients. CONCLUSIONS: MPCT should be double-reported, at least initially. "Possible" lesions should be ignored. Analysis of the graph of conditional probability applied to a group of frail, elderly patients with a high mortality from all causes (33% in our study) suggests: (1) if MPCT suggests definite or probable carcinoma, regardless of the pre-test probability, the post-test probability is high enough to warrant further action, (2) frail, elderly patients with a low pre-test probability for CRC and a negative MPCT should not have further investigation, (3) frail, elderly patients with a higher pre-test probability of CRC (such as those presenting with rectal bleeding) and a negative MPCT should have either double contrast barium enema (DCBE) or colonoscopy as further investigations or be followed clinically for 3-6 months. MPCT was acceptable to patients and clinicians and may reveal significant extra-colonic pathology.

Aged↗
PubMed2001

The value of digital personal dosemeters in angiography/interventional radiology: preliminary experience.

New interventional procedures tend to involve longer screening times than were hitherto used in radiology. A careful audit of technique and shielding facilities needs to be performed to ensure that patient and operator doses are optimised. This paper explores the use of digital dosemeters to evaluate operator dose. Equipment related parameters, e.g. screening time, dose-area-product (DAP) readings, were not found to be strongly correlated to operator dose. The real time display on the electronic dosemeter is a non-intrusive indicator of the efficacy of operator protection strategies.

Angiography↗
PubMed2000

The meaning of diagnostic test results: a spreadsheet for swift data analysis.

AIMS: To design a spreadsheet program to: (a) analyse rapidly diagnostic test result data produced in local research or reported in the literature; (b) correct reported predictive values for disease prevalence in any population; (c) estimate the post-test probability of disease in individual patients. MATERIALS AND METHODS: Microsoft Excel(TM)was used. Section A: a contingency (2 x 2) table was incorporated into the spreadsheet. Formulae for standard calculations [sample size, disease prevalence, sensitivity and specificity with 95% confidence intervals, predictive values and likelihood ratios (LRs)] were linked to this table. The results change automatically when the data in the true or false negative and positive cells are changed. Section B: this estimates predictive values in any population, compensating for altered disease prevalence. Sections C-F: Bayes' theorem was incorporated to generate individual post-test probabilities. The spreadsheet generates 95% confidence intervals, LRs and a table and graph of conditional probabilities once the sensitivity and specificity of the test are entered. The latter shows the expected post-test probability of disease for any pre-test probability when a test of known sensitivity and specificity is positive or negative. RESULTS: This spreadsheet can be used on desktop and palmtop computers. The MS Excel(TM)version can be downloaded via the Internet from the URL ftp://radiography.com/pub/Rad-data99.xls CONCLUSION: A spreadsheet is useful for contingency table data analysis and assessment of the clinical meaning of diagnostic test results.

Bayes Theorem↗
PubMed2000

The role of hepatic arterial Doppler ultrasound after liver transplantation: an 'audit cycle' evaluation.

AIMS: To compare the diagnostic performance of hepatic arterial (HA) Doppler ultrasound post-liver transplantation for hepatic artery thrombosis and stenosis in our unit with the literature. To evaluate the role of the technique in clinical practice. MATERIALS AND METHODS: In a two-phase 'audit cycle' study, adult OLT patients had Doppler studies comprising detection of HA flow and measurements of peak systolic velocity, resistive index and systolic acceleration time. In phase I, patients had Doppler examinations 'routinely' and for any hepatic biochemical abnormality. In phase II, Doppler ultrasound was performed early post-OLT and later only if a senior transplant clinician suspected graft ischaemia. In addition to HA measurements the waveform was visually assessed. Clinical outcome was the 'gold standard'. RESULTS: Phase 1: 38 patients, 40 OLT operations, 125 Doppler studies; 14 arteriograms. Phase 2: 35 patients, 42 OLT operations, two HA angioplasties, one HA revision, one non-occlusive thrombus, 140 studies; 17 arteriograms. Results; Phase 1 [Phase 2]: sensitivity 80% [100%]; specificity 71% [81%]; PPV 28% [56%]; NPV 96% [100%]; incidence of HA abnormality 12.5% [19. 5%]; likelihood ratio of negative result 0.28 [0]; of positive result 2.8 [5.3]. CONCLUSION: Previously reported results are reproducible. Normal HA waveform should also be a criterion of normality. The technique is very sensitive but relatively non-specific. Predictive values improve with discriminate use. MacEneaney, P. M. (2000). Clinical Radiology55, 517-524.

Adult↗
PubMed2000

Applying 'evidence-based medicine' theory to interventional radiology. Part 2: a spreadsheet for swift assessment of procedural benefit and harm.

AIM: To design a spreadsheet program to analyse interventional radiology (IR) data rapidly produced in local research or reported in the literature using 'evidence-based medicine' (EBM) parameters of treatment benefit and harm. MATERIALS AND METHODS: Microsoft Excel(TM)was used. The spreadsheet consists of three worksheets. The first shows the 'Levels of Evidence and Grades of Recommendations' that can be assigned to therapeutic studies as defined by the Oxford Centre for EBM. The second and third worksheets facilitate the EBM assessment of therapeutic benefit and harm. Validity criteria are described. These include the assessment of the adequacy of sample size in the detection of possible procedural complications. A contingency (2 x 2) table for raw data on comparative outcomes in treated patients and controls has been incorporated. Formulae for EBM calculations are related to these numerators and denominators in the spreadsheet. The parameters calculated are benefit - relative risk reduction, absolute risk reduction, number needed to treat (NNT). Harm - relative risk, relative odds, number needed to harm (NNH). Ninety-five per cent confidence intervals are calculated for all these indices. The results change automatically when the data in the therapeutic outcome cells are changed. A final section allows the user to correct the NNT or NNH in their application to individual patients. RESULTS: This spreadsheet can be used on desktop and palmtop computers. The MS Excel(TM)version can be downloaded via the Internet from the URL ftp://radiography.com/pub/TxHarm00.xls. CONCLUSION: A spreadsheet is useful for the rapid analysis of the clinical benefit and harm from IR procedures.

Evidence-Based Medicine↗
PubMed2000

Applying 'technology assessment' and 'evidence based medicine' theory to interventional radiology. Part 1: Suggestions for the phased evaluation of new procedures.

AIM: To compare and contrast interventional radiology (IR) clinical and research practices with the technology assessment and evidence-based medicine (EBM) paradigms and make suggestions for the phased evaluation of new IR procedures. MATERIALS AND METHODS: Course literature of the Association of University Radiologists' 'Basic Technology Assessment for Radiologists' course and the McMaster University Health Information Research Unit's 'How to Teach Evidence-Based Medicine 1999' course were used to identify major publications in each discipline. A computer search was performed to seek other relevant literature. A model of traditional development of IR procedures was developed. Suggestions for the phased evaluation of IR procedures were derived. RESULTS: As in diagnostic radiology, several levels of progressively stronger IR study design can be described and related to EBM 'levels of evidence'. These range from case reports and case series through case-control and cohort studies to randomized controlled trials (RCTs). The major weakness in the existing IR literature is the predominance of small, uncontrolled, case series. Randomized controlled trials are likely to provide the best possible evidence of effectiveness. They are expensive and randomization is sometimes unethical or impractical. Case-control and cohort studies have been under-utilized. Evidence-based medicine indices of benefit and harm have not yet been applied in IR and may have clinical advantages over traditional statistical methods. A literature search (10 years) using MeSH terms 'radiology, interventional' and 'efficacy' yielded 30 papers. Combining 'radiology, interventional' and 'evidence-based medicine' yielded no papers. Comparative searches substituting the term 'diagnostic imaging' for 'radiology, interventional' yielded 4883 and 62 papers, respectively. CONCLUSION: Principles of technology assessment and EBM can be applied to the investigation of new IR procedures. A tool is needed to simplify the application of EBM analytic methods. Better education in research methods is needed to raise the levels of evidence provided by the bulk of IR research and allow new procedures to be introduced into practice appropriately. Malone, D. E. & MacEneaney, P. M. (2000). Clinical Radiology55, 929-937.

Evaluation Studies as Topic↗
PubMed2000

Sedation and analgesia in adult patients: evaluation of a staged-dose system based on body weight for use in abdominal interventional radiology.

PURPOSE: To evaluate the safety and effectiveness of a systematic protocol for sedation and analgesia in interventional radiology. MATERIALS AND METHODS: Ninety-one adult patients underwent 113 abdominal interventional procedures. Fentanyl citrate and midazolam hydrochloride were administered in one to five steps (A, B, C, D, E) until the patient was drowsy and tranquil at the effective loading dose (ELD). Doses per step were as follows: A, fentanyl 1 microg per kilogram of body weight; B, midazolam 0.010-0.035 mg/kg; C, repeat dose in A; D, repeat half the dose in B; and E, midazolam 1-2-mg boluses (maximum, 0.15 mg/kg). RESULTS: The ELD was reached in no procedure after step A, in 70 after B, in 23 after C, and in 18 after D. Step E was needed in two procedures. The mean maximum pain score (scale of 0 to 10) was 3.4; pain scores in 85 (75%) procedures were 4 or less (discomforting). Severe pain occurred in seven (6%) procedures. Hypoxia (oxygen saturation < 90%) occurred in 11 (22%) procedures performed in patients breathing room air and four (6%) performed in those breathing supplemental oxygen (P: =.04). All patients responded to supplemental oxygen. CONCLUSION: This stepwise "ABCDE protocol" allows safe and effective sedation of patients. It is easy to use and may be useful in training radiology residents, staff, and nurses in the techniques of sedation and analgesia. Supplemental oxygen should be used routinely.

Adolescent↗
PubMed1996

Diagnosis of Hirschsprung's disease.

OBJECTIVE: Our aims were to determine the validity of using low-osmolality water-soluble contrast enemas (WSCE) in neonates and infants with suspected Hirschsprung's disease (HD) and to devise a scoring system that uses a checklist of radiologic signs to determine the probability of HD. MATERIALS AND METHODS: The records of all patients referred by pediatric surgeons from 1988 through 1992 for the radiologic investigation of possible HD were retrospectively reviewed. Thirty-eight patients who were from 2 days to 9 months old were studied; 20 of them were neonates (less than 1 month old). Of all the patients, 24 underwent WSCE and the other 14 underwent barium enema. For all patients, HD had been diagnosed by rectal biopsy or excluded by biopsy, clinical follow-up, or both. Radiographs were read by a gastrointestinal radiologist who used a checklist of diagnostic criteria reported in the literature. The sensitivity had specificity of the findings were compared with those in the literature. RESULTS: Of the 18 patients with HD, 12 were neonates. All reported radiologic diagnostic criteria were seen; the frequency, sensitivity, and specificity of the findings were reported. Twenty percent (n = 2) of HD patients in the WSCE group (n = 10) had negative findings. Two of the 12 neonates developed colonic perforation, one during the enema and the other within 24 hr of the procedure. CONCLUSION: WSCE has a sensitivity and specificity equivalent to those of the barium enema for the detection of HD. For the two patients with perforation, the use of WSCE was of considerable benefit, avoiding the problems associated with barium spillage into the peritoneal cavity. A scoring system for diagnostic enemas is feasible.

Barium Sulfate↗
PubMed1995

Improving visualization of distal and terminal ileum during the small bowel meal: an evaluation of fluoroscopic manoeuvres.

This study evaluated a variety of fluoroscopic manoeuvres used during small bowel meals for assessment of the terminal ileum and pelvic loops of small bowel. The purpose was to identify those manoeuvres which provide maximum diagnostic yield. Fifty-six consecutive patients undergoing small bowel meal and pneumocolon entered the study. The individual manoeuvres were graded and their contribution to diagnostic quality determined. An analysis of variance was used to determine the diagnostic value of the manoeuvres. There was a significant difference in the diagnostic quality provided by the different manoeuvres. Compression of the terminal ileum with the 'F spoon' and of the pelvic bowel loops with the compression paddle in the supine position provided the best diagnostic information in single contrast. The double contrast images obtained with the pneumocolon contributed most to the diagnostic quality of the examination. The results enable us to recommend a sequence of manoeuvres which are most likely to provide diagnostic views of the terminal ileum and pelvic ileal loops yielding maximum information and optimizing use of fluoroscopic time.

Barium Sulfate↗
PubMed1995

Fibrin sealant in interventional radiology: a preliminary evaluation.

Tisseel, a fibrin sealant not approved for use in the United States, was tested in abdominal fistulas and sinuses (13 patients) and interventional biliary procedures (11 patients). The two components of Tisseel were introduced via a double-lumen catheter and formed a fibrin gel at the point of contact. Tracts were sealed permanently in seven fistulas and sinuses and in all 11 biliary cases.

Adult↗
PubMed1994

Reevaluation of the sensitivity of impedance plethysmography for the detection of proximal deep vein thrombosis.

BACKGROUND: To reevaluate the sensitivity of impedance plethysmography (IPG) for proximal deep vein thrombosis (DVT) and to establish a relationship between the location and size of thrombi and the results of IPG. DESIGN: Prospective cohort study. METHODS: One hundred thirty-two consecutive patients with clinically suspected DVT underwent IPG testing and most (n = 118) underwent contrast-enhanced venography; in 14 patients, venous ultrasonography was performed and demonstrated definitive proximal DVT in which the size and extent of the thrombus could be delineated. All patients with dubious or normal ultrasound results underwent contrast-enhanced venography. All tests were performed and test results were interpreted without knowledge of the results of the other tests. Patients were considered to have proximal DVT if this was demonstrated on venography or ultrasound, calf DVT if this was demonstrated on venography, or no DVT if venography yielded normal findings. The sensitivity and specificity of IPG for DVT were calculated. RESULTS: Of the 132 patients, 40 (30%) had proximal DVT, seven (5%) had calf DVT, and 85 (64%) had no DVT. The sensitivity of IPG for proximal DVT was 65% and the specificity was 93%. Of the proximal vein thrombi, IPG detected three (23%) of 13 that involved the popliteal vein but not the superficial femoral vein and 23 (85%) of 27 proximal vein thrombi that involved the superficial femoral vein. CONCLUSIONS: Our study demonstrated that the sensitivity of IPG for proximal DVT at our center is only 65%, a figure that is much lower than those reported in earlier studies from our institution. We hypothesize that because of a change in referral practice, an increased proportion of patients with less severe symptoms are now referred to our center than in the past. These patients have thrombi that are smaller, less likely to be occlusive, and therefore less likely to yield abnormal IPG findings.

Adult↗
PubMed1994

Colon cancer detection: an algorithm using endoscopy and barium enema.

A review of findings on flexible sigmoidoscopy (FS), colonoscopy and selected double-contrast barium enema (DCBE) radiographs from a group of 66 patients with rectal bleeding was performed to test the value of an algorithm in the detection of colonic cancers and polyps. In this algorithm the FS findings would direct patients either to colonoscopy or to a modified DCBE which focused attention on the colon proximal to the sigmoid. Only patients with neoplasms diagnosed by FS, or by MDCBE after negative FS, would proceed to colonoscopy. The study population contained four cancers, 11 polyps > 5 mm and 11 polyps < or = 5 mm; FS+MDCBE missed four polyps, all < 5 mm. For polyps > 5 mm and cancer, FS+MDCBE had a sensitivity of 100%, a specificity of 82%, a negative predictive value of 1.0 and a positive predictive value of 0.62. Using the algorithm, 24 patients (36%) would have required colonoscopy. The results suggest that FS+MDCBE is a potentially valuable method for screening patients for colonic neoplasia.

Algorithms↗
PubMed1994

Hepatic interstitial laser photocoagulation. An investigation of the relationship between acute thermal lesions and their sonographic images.

OBJECTIVES: The relationship between hepatic interstitial laser photocoagulation (ILP) lesions and their acute ultrasound images was evaluated. In addition, the natural history of ILP lesions in normal pig liver was documented. METHODS: Eighteen pigs underwent laparotomy and ultrasound-monitored ILP. In part 1 of the study, 12 pigs each had four separate exposures (1.50 W for 60, 100, 300, and 500 seconds) and were divided into four groups according to when they were killed (0, 3, 7, and 21 days). In part 2 of the study, six pigs each had two sequential exposures (1.60 W for 1,000 and then 500 seconds) at separate hepatic sites. Survival time was 3 days. Necropsy and histologic examination were performed in all animals. In 0- and 3-day survivors, actual thermal lesions were compared with "early" (immediately after ILP) and "late" (1 hour after ILP) ultrasound images. RESULTS: In the 300-, 500-, and 1,000-second exposures of parts 1 and 2, thermal lesions were overestimated or approximated by early ultrasound and were underestimated or approximated by late ultrasound. Analysis of variance showed statistically significant differences between thermal lesions and their early and late ultrasound images (F = 18.6, P < .001, no interactions). Time-growth characteristics of ILP lesions were reasonably consistent on ultrasound; exceptions were identifiable 200 seconds into the exposure. In part 2, ultrasound changes were minimal in five of six 500-second (second sequential) technically satisfactory exposures. Thermal lesions were seen at necropsy. All lesions healed by formation of granulation tissue and collagen. CONCLUSIONS: During ILP, early ultrasound images frequently overestimate actual thermal lesions. Ultrasound-monitored ILP of tumors may be most effective if, on early ultrasound, echogenic changes extend beyond the tumor margins. Late ultrasound images underestimate or approximate thermal lesions. Their value in clinical ILP should be investigated. It is unclear why ultrasound images of proven thermal lesions were not seen during 5 of 6 otherwise satisfactory 500-second ILP exposures performed immediately after 1,000-second exposures.

Animals↗