Complex clubfoot: my 5 tips for appropriate evaluation and treatment with the Ponseti method

Complex clubfoot is a term used to describe a subset of patients that received previous treatment, and have distinctive anatomical features: severe equinus, with short first metatarsal, hyperextended big toe, severe plantar flexion of all metatarsals and deep folds through the sole of the foot and above the heel. Most complex clubfeet appear to be idiopathic and is usually associated with a poor casting technique. Complex clubfoot requires an early recognition and an adjustment of the casting protocol using the four finger Ponseti technique. This article gives the treating physician a general overview of the evaluation, treatment, and outcomes of complex clubfoot with the Ponseti method.

Morphologic Features on MR Imaging Classify Multifocal Glioblastomas in Different Prognostic Groups

BACKGROUND AND PURPOSE

Multifocal glioblastomas (ie, glioblastomas with multiple foci, unconnected in postcontrast pretreatment T1-weighted images) represent a challenge in clinical practice due to their poor prognosis. We wished to obtain imaging biomarkers with prognostic value that have not been found previously.

MATERIALS AND METHODS

A retrospective review of 1155 patients with glioblastomas from 10 local institutions during 2006-2017 provided 97 patients satisfying the inclusion criteria of the study and classified as having multifocal glioblastomas. Tumors were segmented and morphologic features were computed using different methodologies: 1) measured on the largest focus, 2) aggregating the different foci as a whole, and 3) recording the extreme value obtained for each focus. Kaplan-Meier, Cox proportional hazards, correlations, and Harrell concordance indices (c-indices) were used for the statistical analysis.

RESULTS

Age (P < .001, hazard ratio = 2.11, c-index = 0.705), surgery (P < .001, hazard ratio = 2.04, c-index = 0.712), contrast-enhancing rim width (P < .001, hazard ratio = 2.15, c-index = 0.704), and surface regularity (P = .021, hazard ratio = 1.66, c-index = 0.639) measured on the largest focus were significant independent predictors of survival. Maximum contrast-enhancing rim width (P = .002, hazard ratio = 2.05, c-index = 0.668) and minimal surface regularity (P = .036, hazard ratio = 1.64, c-index = 0.600) were also significant. A multivariate model using age, surgery, and contrast-enhancing rim width measured on the largest foci classified multifocal glioblastomas into groups with different outcomes (P < .001, hazard ratio = 3.00, c-index = 0.853, median survival difference = 10.55 months). Moreover, quartiles with the highest and lowest individual prognostic scores based on the focus with the largest volume and surgery were identified as extreme groups in terms of survival (P < .001, hazard ratio = 18.67, c-index = 0.967).

CONCLUSIONS

A prognostic model incorporating imaging findings on pretreatment postcontrast T1-weighted MRI classified patients with glioblastoma into different prognostic groups.

[Critical reading of articles about diagnostic tests (part I): Are the results of the study valid?]

In the era of evidence-based medicine, one of the most important skills a radiologist should have is the ability to analyze the diagnostic literature critically. This tutorial aims to present guidelines for determining whether primary diagnostic articles are valid for clinical practice. The following elements should be evaluated: whether the study can be applied to clinical practice, whether the technique was compared to the reference test, whether an appropriate spectrum of patients was included, whether expectation bias and verification bias were limited, the reproducibility of the study, the practical consequences of the study, the confidence intervals for the parameters analyzed, the normal range for continuous variables, and the placement of the test in the context of other diagnostic tests. We use elementary practical examples to illustrate how to select and interpret the literature on diagnostic imaging and specific references to provide more details.

Agreement between semi-automatic radiographic morphometry and Genant semi-quantitative method in the assessment of vertebral fractures

Semi-automatic morphometry is highly reproducible and not time intensive; however, no study has evaluated agreement between semi-automated morphometric methods and the Genant semi-quantitative method performed as a rule by radiologists. Our study shows substantial agreement between both methods; however, semi-automatic morphometry upgrades mild deformities and overestimates the prevalence of fractures.

INTRODUCTION

The aim of this study was to evaluate the agreement between radiologists using the Genant semi-quantitative (SQ) method and semi-automated morphometry in the diagnosis of vertebral fractures in post-menopausal women.

METHODS

Cross-sectional study was conducted in 2006-2007 in an age-stratified population-based sample of 824 post-menopausal women over the age of 50. From this population two sets of 95 and 50 X-ray were randomly extracted to test inter-rater agreement and agreement between SQ and semi-automated morphometry, and vertebral fractures were classified according to both methods. The Genant method was used to homogenise the diagnosis of fractures. Agreement was evaluated with weighted kappa. We evaluated each vertebral body independently and also the whole vertebral column (T4-L4) classifying women into the worst grade of fracture. For the qualitative interpretation of the agreement, we used the criteria described by Landis and Koch (Biometrics 33:159-174, 1977).

RESULTS

The radiologists' agreement was 98.4% (Kappa, 0.75; 95% CI, 0.42-0.89). Agreement between semi-automated morphometry and SQ reached 97.6% and Kappa was 0.86 (95% CI, 0.66-0.94). In the whole evaluation of the spine semi-automated morphometry overestimates, the prevalence of fractures compared with the radiologists were 15.8% of women with fractures and 7.4% of women with moderate-severe fractures by semi-automated morphometry vs. 8.4% and 3.2% by the SQ method. The negative predictive value for MorphoXpress was 99% while the positive was 40%.

CONCLUSIONS

Semi-automated morphometry shows high reliability and a substantial agreement with the SQ approach but overestimates the prevalence of fractures. Its role in routine clinical practice is limited because positive results should be reassessed by qualitative or semi-quantitative methods.

Vertebral endplate changes are not associated with chronic low back pain among Southern European subjects: a case control study

BACKGROUND AND PURPOSE

Data on the association between vertebral endplate changes and low back pain are contradictory. This study was designed to assess whether this association exists among Southern European subjects.

MATERIALS AND METHODS

Patients in this study serving as cases were 35-50 years of age with low back pain lasting >90 days, for whom a lumbar MR imaging had been prescribed. Controls were subjects 35-50 years of age, having a cranial MR imaging for headache with normal findings, and no history of clinically relevant LBP. Two hundred forty cases and 64 controls were recruited consecutively in the radiology services across 6 cities in Spain. Imaging findings and subject characteristics were gathered through previously validated instruments. Radiologists who interpreted MRI were blinded to the subject characteristics. A multivariate logistic regression model was developed to assess the association of vertebral endplate changes with LBP, adjusting for sex, age, body mass index, lifetime exposure to smoking, physical activity, disk degeneration, and the interaction between disk degeneration and vertebral endplate changes.

RESULTS

Vertebral endplate changes were found in 80.4% of the cases and in 87.5% of the controls. In the regression model, disk degeneration was the only variable showing a confounding effect. Results showed that after adjusting for disk degeneration, the presence of vertebral endplate changes is associated with the absence of chronic LBP (OR for LBP: 0.31; 95% CI, 0.10-0.95).

CONCLUSIONS

In Southern European subjects, vertebral endplate changes are not associated with chronic LBP.

Influence of nomenclature in the interpretation of lumbar disk contour on MR imaging: a comparison of the agreement using the combined task force and the nordic nomenclatures

BACKGROUND AND PURPOSE

The CTF nomenclature had not been tested in clinical practice. The purpose of this study was to compare the reliability and diagnostic confidence in the interpretation of disk contours on lumbar 1.5T MR imaging when using the CTF and the Nordic nomenclatures.

MATERIALS AND METHODS

Five general radiologists from 3 hospitals blindly and independently assessed intravertebral herniations (Schmorl node) and disk contours on the lumbar MR imaging of 53 patients with low back pain, on 4 occasions. Measures were taken to minimize the risk of recall bias. The Nordic nomenclature was used for the first 2 assessments, and the CTF nomenclature, in the remaining 2. Radiologists had not previously used either of the 2 nomenclatures. κ statistics were calculated separately for reports deriving from each nomenclature and were categorized as almost perfect (0.81-1.00), substantial (0.61-0.80), moderate (0.41-0.60), fair (0.21-0.40), slight (0.00-0.20), and poor (<0.00).

RESULTS

Categorization of intra- and interobserver agreement was the same across nomenclatures. Intraobserver reliability was substantial for intravertebral herniations and disk contour abnormalities. Interobserver reliability was moderate for intravertebral herniations and fair to moderate for disk contour.

CONCLUSIONS

In conditions close to clinical practice, regardless of the specific nomenclature used, a standardized nomenclature supports only moderate interobserver agreement. The Nordic nomenclature increases self-confidence in an individual observer's report but is less clear regarding the classification of disks as normal versus bulged.

Agreement in the interpretation of magnetic resonance images of the lumbar spine

BACKGROUND

Correlation between clinical features and magnetic resonance imaging (MRI) findings is essential in low-back-pain patients. Most previous studies have analyzed concordance in the interpretation of lumbar MRI among a few radiologists who worked together. This may have overestimated concordance.

PURPOSE

To evaluate intra- and interobserver agreement in the interpretation of lumbar MRI performed in an open 0.2 T system.

MATERIAL AND METHODS

Seven radiologists from two different geographic settings in Spain interpreted the lumbar MRIs of 50 subjects representative of the general Danish population aged 40 years. The radiologists interpreted the images in routine clinical practice, having no knowledge of the clinical and demographic characteristics of the subjects and blinded to their colleagues' assessments. Six of the radiologists evaluated the same MRIs 14 days later, having no knowledge of the previous results. Data on the existence of disc degeneration, high-intensity zones, disc contour, Schmorl nodes, Modic changes, osteophytes, spondylolisthesis, and spinal stenosis were collected in the Nordic Modic Consensus Group Classification form. Intra- and interobserver agreement was analyzed for variables with a prevalence >or=10% and <or=90% by means of the kappa statistic.

RESULTS

Intra- and interobserver agreement was excellent for variables related to Modic changes, and fair to good for disc contour, high-intensity zones, and Schmorl nodes. The evaluations for disc degeneration and osteophytes were found to have fair to good intraobserver agreement and poor interobserver agreement. The agreement for the evaluations of spondylolisthesis and spinal stenosis was not analyzed because they were observed in <10% of reports.

CONCLUSION

Images from 0.2 T MRIs appear to lead to good agreement in the reporting of disc contour, high-intensity zones, Schmorl nodes, and, in particular, Modic changes, suggesting that they can possibly be reliably used for clinical research purposes. In contrast, assessment of osteophytes and disc degeneration is not reliable.

[Association of cavernous and venous angiomas]

INTRODUCTION

Isolated cavernous and venous angiomas are common vascular cerebral malformations. The routine use of magnetic resonance imaging (MRI) in cerebral studies has shown their frequent association.

OBJECTIVE

An analysis of the association characteristics of both lesions (cavernous and venous angiomas), and the relationships with localization, size, patient sex and the use of intravenous contrast material in the diagnosis with MR.

METHODS

A retrospective analysis of the cerebral MRI studies of 37 patients with cavernous angiomas. Statistical relations were established with contingency tables and statistical methods of Pearson c2 and t of Student for independent samples. Results. 52 cavernous angiomas were identified in the 37 patients. No significant statistical differences were found that related the cavernous angioma size, localization or patient sex with the existence of an associated venous angioma. Only the administration of contrast material has shown a statistical significance for the diagnosis.

CONCLUSIONS

The association of cavernous and venous angioma is frequent (30%). This association has prognostic implications, due to bleeding risk, and surgical as it is not recommended the resection of the venous anomaly due to the possible venous infarction. To detect venous angiomas is necessary the administration of contrast material.

[Dementias: diagnostic contribution of imaging and proton magnetic resonance spectroscopy]

INTRODUCTION

The objective is analyze the complementarity between 1H magnetic resonance spectroscopy (MRS) and magnetic resonance (MR) imaging in the global diagnosis of Alzheimer's disease (AD) or vascular dementia (VD).

METHODS

We studied 168 patients with cognitive impairment from AD, VD, mild cognitive impairment (MCI) and major depression. All patients were evaluated by brain MR imaging and MRS using two sample volumes localized at right medial temporal gyrus and posterior parietal gyrus. Metabolites analyzed were N-acetylaspartate (NAA), myo-Inositol (mI), Choline (Cho) and creatine (Cr), as standard references for obtaining the Co/Cr, mI/Cr and NAA/Cr ratios. Imaging and spectroscopy alterations were graded from 0 to 4 and the average of both was used to draw ROC and SROC curves. Area under ROC curve (Az) was used as a measure of discriminative ability.

RESULTS

Combination of MR imaging and MRS significantly improved AD diagnosis (Global Az: 0.722 vs. MR imaging Az: 0.624; p: 0.003). However, the combination of MR imaging and MRS did not improve VD diagnosis. SROC curve obtained for the diagnosis of global dementia was Az: 0.6658 with 0.67 sensitivity and 0.65 specificity.

CONCLUSIONS

Combination of both MR techniques significantly improved AD diagnosis versus MR imaging alone. More studies are needed to enhance VD classification. Metabolic data found by MRS can be useful to differentiate cognitive impairment

[Assessment of reliable quantification of the dynamics of cerebrospinal fluid by magnetic resonance imaging in idiopathic normal pressure hydrocephalus]

INTRODUCTION

A combination of good clinical selection with reliable quantification of diverse parameters that characterize the dynamics of cerebrospinal fluid (CSF) flow from phase-contrast magnetic resonance imaging may identify patients with idiopathic normal pressure hydrocephalus (NPH).

MATERIAL AND METHODS

We have carried out a quantitative analysis of 38 subjects (19 healthy subjects and 19 patients with suspected idiopathic NPH). The images were acquired using a 1.5 T MR unit with a phase-contrast sequence in an oblique-transversal plane perpendicular to the Sylvius aqueduct codified to 20 cm/s and with 27 observations per cardiac cycle by means of retrospective synchronization. The area was defined to half the height of the peak velocity, to maximize accuracy. Parameters quantified were mean flow, maximum systolic and diastolic flow, maximum systolic and diastolic velocity, mean velocity, CSF production and stroke volume.

RESULTS

All the parameters measured showed a significant difference (ANOVA: p<or=0,05) between controls and patient except for the maximum systolic velocity (p=0.17). It was observed in the discriminant analysis that the two groups (controls and patients) were classified correctly in 92.1% with the use of the maximum systolic flow and CSF production.

CONCLUSIONS

Semiautomatic quantification of the dynamics of CSF by means of MRI differentiates patients with hyperdynamic state from the control subjects, with significant differences that can be used to classify idiopathic HNP.

[Cognitive impairment: classification by proton magnetic resonance spectroscopy and the contributions of conventional magnetic resonance imaging]

OBJECTIVE

To analyze the diagnostic accuracy of proton magnetic resonance spectroscopy (1H MRS) in patients with cognitive impairment and to establish the usefulness of complementary information provided by conventional magnetic resonance imaging (MRI).

MATERIAL AND METHODS

64 patients with cognitive impairment, including Alzheimer's disease (AD) (n=31), vascular dementia (n=6), mild cognitive impairment (MCI) (n=9), and major depression (n=18), were studied. All patients underwent cerebral MRI and single-volume 1H MRS using two echo times (TE, 31 and 136 ms) in the posterior cingulate gyrus and right temporal lobe. The metabolites analyzed were N-acetylaspartate (NAA), myo-Inositol (mI), choline (Ch), and creatine (Cr), and the ratios of Ch/Cr, mI/Cr, NAA/mI and NAA/Cr were calculated. In order to differentiate among the different types of cognitive impairment, the alterations in imaging and spectroscopy findings were graded from 0 to 4, as was the mean combination of the two, and then ROC curves were obtained.

RESULTS

Statistically significant differences were found between the spectra of patients with dementia (AD and vascular dementia) and those without dementia (MCI and depression) in the posterior cingulate gyrus. The NAA/mI ratio yielded the best area under the ROC curve, with the best sensitivity (82.5%) and specificity (72.7%) in the diagnosis of AD. The NAA/mI and mI/Cr quotients differentiated between the four degenerative pathologies causing the cognitive impairment. The combination of MRI and 1H MRS significantly improved the accuracy of the diagnosis of AD.

CONCLUSIONS

The metabolic differences found among patients with cognitive impairment using 1H MRS can be useful for differentiating AD, vascular dementia, MCI, and depression. The combination of spectroscopy and MRI findings is useful in the diagnosis of AD.

Low-high and high-low biphasic injection forms in computed tomography examinations of the upper abdomen

PURPOSE

To analyze the influence of different biphasic and monophasic injection rate protocols in abdominal computed tomography (CT).

MATERIAL AND METHODS

A randomized, consecutive, parallel group study was designed and conducted in 60 patients studied with the same CT helical protocol. Patients were randomly distributed into three groups: (A) monophasic (120 ml at 2.5 ml/s); (B) low-high biphasic (120 ml, first 60 ml at a rate of 2 ml/s, the other 60 ml at 2.5 ml/s); and (C) high-low biphasic (120 ml, first 60 ml at a rate of 2.5 ml/s, the other 60 ml at 2 ml/s). All patients were injected with 300 mg I/ml non-ionic contrast media at a fixed delay time of 55 s. Contrast enhancement efficacy was evaluated by attenuation coefficient measurements.

RESULTS

Although non-significant, monophasic protocol enhancements were higher than biphasic protocol enhancements in all measurements except aortic bifurcation (p=0.003). At this level, biphasic protocols obtained an increased mean enhancement from 7.6% to 2.5% compared to monophasic protocols.

CONCLUSION

Monophasic contrast agent injection in helical CT of the upper abdomen produces a higher enhancement of parenchymal and venous structures. No significant difference was observed between low-high and high-low biphasic protocols.

Comparative Study of Muromonab-CD3 (OKT3) Versus Daclizumab (Zenapax) in Cardiac Transplantation at Our Center

Recent studies support the addition of new immunosuppressive drugs as cytolytic induction therapy in cardiac transplantation. We carried out a comparative study comprising 52 patients who had undergone cardiac transplantation at our center. Thirty patients received muromonab-CD3 (OKT3, Janssen-Cilag, The Netherlands) as the induction therapy, whereas 22 patients received Daclizumab (Zenapax, Hoffman-La Roche, Nutley, NJ, USA) instead. All patients received cyclosporine or tacrolimus, mycophenolate, and steroids. Over an average follow-up period of 23.21 +/- 18 months, we analyzed retrospectively the incidence of grade > or = 3A biopsy-confirmed acute rejection episodes, the presence of infectious processes at 1 and 6 months, the occurrence of significant secondary effects, and the necessity to modify the immunosuppressive therapy during the follow-up. The results suggest that daclizumab is linked to a decreased incidence of grade > or = 3A biopsy-confirmed acute rejection and to a reduced necessity to modify the immunosuppressive therapy during the medium-term follow-up.

Magnetic resonance myelography evaluation of the lumbar spine end plates and intervertebral disks

PURPOSE

To evaluate the value of magnetic resonance (MR) myelography in the evaluation of intervertebral disk and end-plate degenerative changes in the lumbar spine.

MATERIAL AND METHODS

Conventional MR and MR myelography examinations were performed in 150 consecutive patients (69 F and 81 M, mean age 45+/-15 years, range 18 89). Sagittal T1 and T2-weighted TSE images were compared to MR myelography obtained with a multishot-TSE-T2-weighted sequence (4000/250/fat suppression). Coronal, sagittal, and both oblique MR myelography projections were obtained. Image analysis was carried out independently by two radiologists who categorized lumbar disks into normal, degenerated, or edematous; and vertebral end plates into normal, edematous, or with fatty changes. The proportions were statistically compared at every lumbar intervertebral level.

RESULTS

There was good agreement in the classification of disk disease (Kappa: 0.8-0.9). MRI detected a larger number of disk degeneration and end-plate fatty metamorphosis, while the MR myelography technique depicted a larger number of edematous disks and end plates.

CONCLUSION

MR myelography was of limited value in detecting the same vertebral end-plate changes observed in MRI, although with similar findings in disk disease. However, the higher detection of edema changes by MR myelography should be analyzed prospectively, as it could be more sensitive than conventional MR sequences.

Dural enhancement with primary calvarial lesions

The purpose of this study was to relate the pathological and imaging features of dural enhancement and meningeal sign ("dural tail") on contrast-enhanced T1-weighted magnetic resonance (MR) images from patients with primary calvarial lesions as well to assess the accuracy of MR imaging in predicting dural invasion. Thirty-two calvarial tumors studied with contrast-enhanced MR imaging and histopathological examination of the dural specimens were reviewed. Sixteen patients presented dural enhancement, eight with tumor invasion. Tumoral invasion of the dura was observed in one case without enhancement. Malignant lesions showed enhanced dura more commonly than benign lesions (P=0.02). Nodular and discontinuous dural enhancement was statistically associated with dural invasion (P=0.05). Dural tail did not show a specific pathological association. Meningeal enhancement is a nonspecific reaction to calvarial lesions unless nodular and discontinuous. False-negative and -positive cases of dural invasion imply some limitation of contrast-enhanced MR imaging in predicting dural invasion by calvarial neoplasms.

Cognitive impairment: classification by 1H magnetic resonance spectroscopy

1H magnetic resonance spectroscopy (MRS) allows accurate and non-invasive in vivo metabolic study, and is a useful tool for the diagnosis of different forms of dementias. Cognitive impairment pathologies have been almost exclusively studied with MRS by comparison with healthy without a global comparison amongst Alzheimer disease (AD), vascular dementia, mild cognitive impairment (MCI) and major depression patients with cognitive impairment. Whereas decrease of N-acetylaspartate (NAA) and increase myo-Inositol (mI) at different brain locations by 1H MRS are common features of AD, Choline (Cho) alterations have been inconclusive. In our study, 64 patients with cognitive impairment were evaluated by 1H MRS using two echo times (31 and 136 ms). There were statistical differences between dementia (AD and vascular dementia) and non-dementia (MCI and depression) spectra at posterior cingulate gyrus. Cho/Cr, mI/Cr and NAA/Cr have been valuables for the differentiation amongst the different cognitive impairment entities. NAA/mI provides the best area under the ROC curve with the highest sensitivity (82.5%) and specificity (72.7%) in diagnosing AD. NAA/mI and mI/Cr ratios differed amongst the four cognitive impairment degenerative pathologies. Metabolic MRS differences found amongst patients with cognitive impairment entities can be useful to differentiate between AD, vascular dementia, MCI and depression.

MR-myelography as an adjunct to the MR examination of the degenerative spine

Our objective was to analyse the usefulness of single-slice MR-myelography images as a complementary test to conventional MR of the spine in patients with clinically suspected degenerative spine disease. A prospective analysis of 1022 consecutive patients studied with conventional MR and MR-myelography (four acquisitions: one coronal plane, one sagittal plane, and two oblique lateral, right and left planes) examinations was performed. Conventional MR and MR-myelography studies were classified as positive when morphological or structural alterations were noted. Positive MR-myelography information was also categorized as relevant if findings were considered important and radiologically significative to the final diagnosis (either by increasing the radiologists confidence in the diagnosis or because the findings were not observed in the conventional study). Other positive findings were considered non- relevant. There were 62% cases considered positive in the MR-myelography examination. Of them, 3% revealed no alterations on the conventional MR examination. Of the negative MR-myelography studies, 75% had a positive conventional MR examination. Considered as diagnostic techniques, their Kappa concordance was poor. However, MR-myelography complemented the information obtained with the conventional MR examination of the spine, this information being relevant to the final MR diagnosis in 22% of the total number of cases. The contribution of MR-myelography was not different in the three spinal levels. In conclusion, MR-myelography complements the information obtained with conventional MR in a large number of cases.

Comparison of different injection forms in CT examination of the upper abdomen

BACKGROUND

The optimal technique for administration of intravenous contrast medium in computed tomography (CT) remains controversial. Therefore, we analyzed the influence of variable-rate injection protocols.

METHODS

A double-blind, parallel-group study was conducted in 60 patients studied with the same helical CT contrast-enhanced protocol. Patients were randomly distributed into three groups: monophasic (123 mL at 2.5 mL/s), biphasic (123 mL, 60 mL at 1.5 mL/s and then 63 mL at 2.5 mL/s), and sigmoid (0.6 mL/s ending at 2.5 mL/s). Contrast-enhancement efficacy was evaluated by attenuation coefficient measurements.

RESULTS

The monophasic injection protocol produced a statistically higher liver, inferior vena cava, and portal enhancement than did the low-high biphasic and sigmoid protocols. The biphasic protocol produced a statistically higher enhancement in the superior aorta. The enhancement obtained with the monophasic protocol was always higher than or equal to those obtained with the biphasic protocol in all measurement protocols except in the superior aorta and the aortic bifurcation.

CONCLUSIONS

A monophasic injection produces better parenchymal and venous enhancement. When arterial enhancement is important, a low-high biphasic protocol can be used. A sigmoid protocol, with the parameters used in our series, is significantly less effective.

Diagnóstico de las lesiones de la calota. Selección de variables por redes neuronales y regresión logística

OBJECTIVES

To establish the minimun set of features needed in the diagnosis of calvarial lesions using computed tomography (CT) and to assess the accuracy of logistic regression (LR) and artificial neural networks (NN) for their diagnosis.

MATERIAL AND METHODS

167 patients with calvarial lesions as the only known disease were enrolled. The clinical and CT data were used for LR and NN models. Both models were tested with the jacknife method. The final results of each model were compared using the area under ROC curves (A 2 ).

RESULTS

The lesions were 73.1 % benign and 26.9% malignant. There was no statistically significant difference between LR and NN in differentiating malignancy. In characterizing the histologic diagnoses, NN was statistically superior to LR. Important NN features needed for malignancy classification were age and edge definition, and for the histologic diagnoses matrix, marginal sclerosis and age.

CONCLUSIONS

A minimum four features is needed to diagnose these lesions, not being important patients' symptoms. NNs offer wide possibilities over statistics for the calvarial lesions study besides a superior diagnostic performance.

Long-term outcome of patients with asystole induced by head-up tilt test

AIMS

To analyse the long-term outcome of the largest reported cohort of patients presenting asystole during head-up tilt test.

METHODS AND RESULTS

Since 1990, 1322 patients with syncope of unknown origin have undergone tilt-table testing. Of those, 330 patients (24 X 9%) presented an abnormal response (syncope or pre-syncope). Furthermore, 58 of those patients (17 X 5%) suffered a period of asystole (> or = 3000 ms) during the test. Asystole (median (interquartile range)) lasted 10 (4, 19 X 2) s (range 3-90). Two different protocols (angles) of tilting (Westminster (60 degrees) n=1124; isoproterenol (80 degrees) n=198)) influenced the time to the syncopal episode (13 (6 X 5, 20 X 5) vs 2 (1, 6 X 5) min, P=0,0005) but not the duration of the asystole. During this period, therapy for asystole featured three different stages: first patients were treated with pacemakers; later drug therapy (metoprolol and/or etilefrine) was recommended; lastly (from 1995), no specific treatment was given. In a cohort age- and gender-matched study, those patients without were compared to those with asystole in a 2:1 basis. During 40 X 7 months of follow-up (17 X 7, 66 X 8), 12 patients (20 X 6%) with asystole had syncopal recurrences. Furthermore, 34 patients (28 X 8%) without asystole presented syncopal episodes during a follow-up of 51 X 6 months (29 X 3, 73 X 1) (P=ns). The Kaplan-Meier analysis in patients with and without asystole showed a mean time free of recurrence of 92 X 6 +/- 6 months vs 82 X 6 +/- 4 X 7 months (P=ns). The previous number of syncopes had a significant relationship with recurrences (P=0 X 002), but not therapy. There were no cardiac related deaths.

CONCLUSIONS

(1) Asystole during head-up tilt test does not imply a malignant outcome and syncope recurrence is low; (2) pacemaker or drug therapy do not significantly influence outcome which correlates to the previous number of syncopal episodes but not to gender, age, asystole occurrence, asystole duration and timing to asystole during head-up tilt test; (3) tilting protocol (angle) might influence time to and incidence of asystole during head-up tilt test.

[School-age smoking in the province of Seville. Epidemiology and influence of personal and social environment (smoking prevention campaign, 1998-1999)]

OBJECTIVE

To study the prevalence os smoking in school children in Sevilla and the influence of personal and social environment on smoking patterns.

METHODS

This study was part of a preventative anti-smoking campaign in schools. Students filled in anonymous questionnaires based on the World Health Organization survey instrument for population attitudes and habits.

RESULTS

We surveyed 3385 students between 10 and 19 years of age at 47 schools in Seville and 28 villages in the surrounding province. Current smoking was reported by 19.1% of the students; slightly more girls (19.8%) than boys (18.3%) smoked. Smoking was related to having an older brother or sister who smoked and particularly to having friends who smoked (OR 20.5). The adolescents reported that parents were less permissive than the rest of their environment. Smokers associated tobacco with values such as independence and freedom; they believed that smoking might have an impact on health, although their conviction was less strong than that of non-smokers, regular smokers had high expectations of continuing.

CONCLUSIONS

We found a high proportion of smokers among students of both sexes. Starting and continuing to smoke during adolescence is considerably influenced by the social environment of peers and is possibly affected by messages of independence and freedom transmitted through tobacco industry advertising.

Validation procedures in radiologic diagnostic models. Neural network and logistic regression

OBJECTIVE

To compare the performance of two predictive radiologic models, logistic regression (LR) and neural network (NN), with five different resampling methods.

METHODS

One hundred sixty-seven patients with proven calvarial lesions as the only known disease were enrolled. Clinical and CT data were used for LR and NN models. Both models were developed with cross-validation, leave-one-out, and three different bootstrap algorithms. The final results of each model were compared with error rate and the area under receiver operating characteristic curves (Az).

RESULTS

The NN obtained statistically higher Az values than LR with cross-validation. The remaining resampling validation methods did not reveal statistically significant differences between LR and NN rules.

CONCLUSIONS

The NN classifier performs better than the one based on LR. This advantage is well detected by three-fold cross-validation but remains unnoticed when leave-one-out or bootstrap algorithms are used.

Validation of logistic regression models in small samples: application to calvarial lesions diagnosis

We have used the leave-one-out (LOO) method and the area under the receiver operating characteristic (ROC) curve to validate logistic models with a sample of 167 patients with calvarial lesions. Seven logistic regression models were developed from 12 clinical and radiological variables to predict the most common diagnoses separately. The LOO method was used to test the validity of the equations. The discriminant power of every model was assessed by means of the area under the ROC curve (Az). The model with the greatest discrimination ability for the whole data set was the osteoma equation (Az = 0.951). The discriminatory ability of the statistical models decreased significantly with the LOO procedure, having the malignancy model the highest value (Az = 0.931). The LOO method can obtain a high benefit from small samples in order to validate prediction rules. In studies with small samples, resampling techniques such as the LOO should be routinely used in predictive modeling. This method may improve the forecast of infrequent diseases, such as calvarial lesions.