Demonstration of neurovascular compression in trigeminal neuralgia with magnetic resonance imaging. Comparison with surgical findings in 52 consecutive operative cases.

Until recently, the inability to demonstrate neurovascular compression of the trigeminal nerve preoperatively resulted in surgery being offered only in cases of severe trigeminal neuralgia (TGN), frequently after a prolonged trial of medical treatment and following less invasive procedures, despite the fact that posterior fossa microvascular decompression gives long-term pain relief in 80% to 90% of cases. To assess whether vascular compression of the nerve could be demonstrated preoperatively, high definition magnetic resonance tomographic angiography (MRTA) was performed in 50 consecutive patients, five of whom had bilateral TGN, prior to posterior fossa surgery. The imaging results were compared with the operative findings in all patients, including two patients who underwent bilateral exploration. Vascular compression of the trigeminal nerve was identified in 42 of 45 patients with unilateral symptoms and on both sides in four patients with bilateral TGN. In the last patient with bilateral TGN, neurovascular compression was identified on one side, and on the other side the compressing superior cerebellar artery was separated from the nerve by a sponge placed during previous surgery. There was full agreement regarding the presence or absence of neurovascular compression demonstrated by MRTA in 50 of 52 explorations, but MRTA misclassified four vessels compressing the trigeminal nerve as arteries rather than veins. In two cases, there was disagreement between the surgical and MRTA findings. In the first of these cases, surgery revealed distortion of the nerve at the pons by a vein that MRTA had predicted to lie 6 mm remote from this point. In the second patient, venous compression was missed; however, this patient was investigated early in the series and did not have gadolinium-enhanced imaging. In nine cases, MRTA correctly identified neurovascular compression of the trigeminal nerve by two arteries. Moreover, MRTA successfully guided surgical reexploration in one patient in whom a compressing vessel was missed during earlier surgery and also prompted exploration of the posterior fossa in two patients with multiple sclerosis and one patient with Charcot-Marie-Tooth syndrome, in whom neurovascular compression was identified preoperatively. It is concluded that MRTA is an extremely sensitive and specific method for demonstrating vascular compression in TGN. As a result, open surgical procedures can be recommended with confidence, and microvascular decompression is now the treatment of choice for TGN at the authors' unit. They propose MRTA as the definitive investigation in such patients in whom surgery is contemplated.

Fetal and fetal brain volume estimation in the third trimester of human pregnancy using gradient echo MR imaging.

The Cavalieri method has been applied in combination with gradient echo magnetic resonance imaging (MRI) to investigate the increase in the volume of the fetus and fetal brain in the third trimester of pregnancy. Eighteen women with singleton pregnancies were recruited. Birthweights for the fetuses all lay within the 10-90th centile based on Liverpool data. A regression analysis, weighted using values derived from the coefficient of error predicted for each volume estimate, revealed a linear relationship between total fetal volume and gestational age (R2 = 0.88) and between fetal brain volume and gestational age (R2 = 0.71) during the third trimester. Fetal volume increased by an average of 25.2 ml per day and fetal brain volume increased by an average of 2.3 mL per day. Fetal brain volume is on average a constant proportion (10%, SD = 2%) of total fetal volume throughout the third trimester. Volume data were also obtained for eight fetuses diagnosed as abnormal. The volume of seven of the eight abnormal fetuses fell outside the 95% confidence interval established from the data obtained for the normal fetuses. However, for only three of the eight abnormal fetuses did brain volume fall outside the 95% confidence interval established for normals, possibly due to brain sparing occurring in asymmetrical growth retardation. The volume of the fetus and fetal brain may be readily estimated directly using the Cavalieri method and magnetic resonance imaging. These parameters represent potentially useful information for assessing fetal growth.

Hominid thumb strength predicted by high resolution magnetic resonance imaging and force measurements in living subjects.

This study investigates whether in-vivo measurements of the morphology of the pollical distal phalanx (PDP) can be used to predict the maximum force that can be exerted by the thumb in flexion at the interphalangeal joint. A predictive equation was obtained via which measurements of fossil PDP's can be used to predict flexion force in hominids. A home-built insertable coil assembly, which increased the available magnetic field gradient strength from 10 to 40 (mT) m-1, was used to acquire high resolution T1-weighted 3D SPGR Magnetic Resonance (MR) images of the left and right thumbs of nine volunteers. The subjects' age, sex, weight, height and self-assessed hand-dominance were recorded. The MR images were transferred to a computer for reformatting of sections in the transverse and volar plane (VP). Measurements were made of the maximum length (ML), breadth (MB), tuft breadth (MT) and joint depth (JD) of the PDP. For each subject the maximum flexion force that could be exerted by each thumb was measured. The mean maximum flexion force generated was 8.21 kg (range 5.68-13.13 kg). Considerable inter-individual variability was observed in the magnitude of the force difference between the left and right thumbs and this is greatest in individuals with the strongest thumbs. The best model produced by multiple linear regression analysis of all the available data has a value of r = 0.77 and needs only the two covariates of sex and weight, i.e. FORCE = 2.217 + 0.6651 x WEIGHT + 2.488 x SEX. However, in order to be useful for predicting the maximum flexion force of the thumb in hominids the model should only contain those parameters which can be measured for fossil PDP's. Accordingly, the best predictive model has a value of r = 0.73 and needs only the two covariates of ML and JD, i.e. FORCE = -10.28 + 0.2053 x ML + 1.571 x JD. The maximum force predicted for any of the hominid fossil PDP's was not significantly different from those recorded for the volunteers in the present study, although they were on average somewhat lower than those obtained for modern humans. This may be a reflection of the hominid's overall smaller body weights.

Automatic analysis of cerebral atrophy.

3D MR data obtained for 10 healthy control subjects have been used to build a brain atlas. The atlas is built in four stages. First, a set of features that are unambiguously definable and anatomically relevant need to be computed for each item in the database. The chosen features are crest lines along which the maximal principal curvature of the surface of the brain is maximal in its associated principal direction. Second, a nonrigid registration algorithm is used to determine the common crest lines among the subjects in the database. These crest lines form the structure of the atlas. Third, a set of crest lines is taken as a reference set and a modal analysis is performed to determine the fundamental deformations that are necessary to bring the individual data in line with the reference set. The deformations are averaged and the set of mean crest lines becomes the atlas. Finally, the standard deviation of the deformations between the atlas and the items in the database defines the normal variation in the relative positions of the crest lines in a healthy population. In a fully automatic procedure, the crest lines on the surface of the brain adjacent to the cerebral ventricles in a patient with primary progressive aphasia were compared to the atlas; confirmation that the brain of this patient demonstrates atrophy was provided by stereological analysis that showed that the volume of the left cerebral hemisphere is 48.8 ml (CE 2.8%) less than the volume of the right cerebral hemisphere in the region of the temporal and frontal lobes. When the amplitude of the deformations necessary to register the crest lines obtained for the patient with the atlas were greater than three standard deviations beyond the variability inherent in the atlas, the deformation was considered significant. Four of the main deformation modes of the longest crest line of the surface of the brain adjacent to the cerebral ventricles were significantly different in the patient with primary progressive aphasia compared to the atlas. The ventricles are preferentially enlarged in the left cerebral hemisphere. Furthermore, they are closer together posteriorly and further apart anteriorly than in the atlas. These observations may be indicative of the atrophy of the temporal and frontal lobes of the left cerebral hemisphere noted in the patient. Ultimately, the approach may provide a useful screening technique for identifying brain diseases involving cerebral atrophy. Serial studies of individual patients may provide insights into the processes controlling or affected by particular disease.

Quantitative magnetic resonance imaging in consecutive patients evaluated for surgical treatment of temporal lobe epilepsy.

We present the results of quantitative Magnetic Resonance Imaging (MRI) in 55 consecutively referred patients with clinical evidence of temporal lobe epilepsy (TLE). The Cavalieri method was used in combination with point counting to provide unbiased estimates of the volume of the left and right hippocampus, amygdala, temporal lobe, lateral ventricles and cerebral hemisphere, and pixel by pixel maps of the T2 relaxation time were computed for both central and anterior sections of the hippocampus. The 99th centiles of hippocampal volume, hippocampal volume asymmetry and T2 relaxation times in 20 control subjects provided limits which identified the presence of MTS. The results of the quantitative MRI were compared with the results of conventional diagnostic MRI, foramen ovale (FO) recording and the WADA test. Thirty-one patients were found to have unilateral MTS (17 left and 14 right) and 7 bilateral MTS. No evidence of MTS was detected in 16 patients. Of the 31 patients diagnosed with unilateral MTS on the basis of hippocampal volume and T2 measurement, 74% and 77% would respectively have received the same diagnosis on the basis of hippocampal volume and T2 measurements alone. In comparison to FO recording, quantitative MRI has a sensitivity of 55% and a specificity of 86%, while conventional diagnostic MRI has a sensitivity of 42% and a specificity of 80% for detection of MTS. Unilateral abnormalities were detected by FO recording in 30% cent of patients who appeared normal on quantitative MRI. WADA test results were available for 40 patients. The findings were consistent with quantitative MRI showing reduced memory function ipsilateral to unilateral MTS in 18 patients, but reduced memory function contralateral to unilateral MTS in two patients, and reduced memory function without MR abnormality in seven patients. WADA testing revealed unilateral memory impairments where MRI found bilateral pathology in 4 patients and in 4 patients in whom quantitative MRI detected unilateral MTS there was no evidence of reduced memory during WADA testing of the corresponding cerebral hemisphere. In the patients with unilateral right MTS a highly significant negative correlation (p = 0.0003) was observed between age of onset and the volume of the contralateral temporal lobe. Quantitative MR imaging of the hippocampus (i.e. volume and T2 measurement) is preferable to conventional radiological reporting for providing objective evidence of the presence of MTS on which to base the referral of patients for surgery, and since it has associated morbidity FO recording is now only being used in selected patients. Furthermore, stereology provides a convenient method for estimating the volume of other brain structures, which is relevant to obtaining a better understanding of the effects of laterality and age of onset of TLE.

Technical considerations in aortography for the investigation of lower limb ischaemia--results from a postal survey.

Eighty-eight radiologists who performed aortography responded to a postal questionnaire. Three-quarters used the transfemoral catheter method and a quarter routinely performed translumbar aortography. The majority used low-osmolality contrast media. Most translumbar aortograms are performed under general anaesthesia and most transfemoral techniques under sedation and/or analgesia. Details of catheters, guide wires and methods of injection were also obtained from the survey.

Delineation of the spleen by a combination of proliposomes with water-soluble contrast media: an experimental study using computed tomography.

Numerous methods for delineating the splenic pulp, including dynamic computed tomography scanning, either are unreliable or have other shortcomings. A method is described for enhancing the spleen using aqueous contrast media in conjunction with proliposomes. While liposomal carrier systems have previously been used for diagnostic purposes, proliposomes circumvent many of the problems associated with the manufacture and handling of liposomes. This enhancement is based on the selective uptake of particulate material by the reticuloendothelial system. While others, by using washed liposomal suspensions, have apparently obtained higher degrees of splenic contrast enhancement, the present study nevertheless shows that significant levels of enhancement are obtainable by a combination of intra- and extraliposomal contrast media.

Factors which influence the occurrence of vascular calcification in the breast.

Breast arterial calcification, as seen on mammography, increases in frequency with advancing age, especially after menopause. No association was found with systemic hypertension. The number of diabetics in the series was too small for comparative purposes. An early menopause and a history of pregnancy were factors which influenced incidence. Oral contraception was associated with a lower incidence of calcification before, but not after menopause. On the other hand, hormonal preparations taken for menopausal symptoms were associated with a lower incidence of calcification in postmenopausal women.

A comparison between iohexol and metrizamide, two nonionic contrast media, in aorto-femoral angiography.

Iohexol, a recently developed non-ionic contrast medium, is shown to be well tolerated on aorto-femoral angiography. The aortic injection of 40 ml of iohexol (350 mg I/ml) was usually associated with a moderate sensation of heat and an absence of pain. A transient fall in blood pressure, no different from that resulting from metrizamide, was associated with some increase in heart rate.

The variation of breast parenchymal patterns with age.

The Wolfe classification of mammographic parenchymal patterns has been applied to 9036 women attending a Breast Cancer Screening Unit. Overall, two thirds fell into high risk categories (P2 and DY). The incidence of DY decreases with age, while the low risk categories (N1 and P1) increase with age. P2 remains constant over most of the age range. The implications of these findings are discussed and comparison is made with other series.

A comparison of three methods for performing barium follow-through studies of the small intestine.

Domperidone 8 mg intravenously and metoclopramide 10 mg intravenously, in patients given a standard barium sulphate preparation, were compared with a rapid-transit barium (E-Z-Paque, E-Z-Em) in a double-blind random controlled manner. E-Z-Paque and metoclopramide given with a standard barium preparation decreased small-bowel transit time and resulted in fewer radiographs being taken. Gastric emptying occurred most rapidly with metoclopramide and a standard barium sulphate preparation. There was no significant difference in the quality or diagnostic accuracy of the examinations with any of the three techniques, and no difference in the incidence of side-effects with the two drugs.

The mammographic breast pattern and oral contraception.

The relationship of oral contraceptive usage to breast parenchymal patterns has been studied in 5319 self-selected women presenting to a breast screening unit. Among premenopausal women, 46.1% had taken an oral contraceptive ("the pill") in the past, and 9.5% were still taking the pill. These patients showed a decreased incidence of P2 patterns and an increased incidence of N1 patterns. Of the post-menopausal women, 14.7% had been on the pill. Similar differences of incidence of parenchymal patterns are noted in these women. The significance of these changes is unclear.

Segmentation and numerical analysis of microcalcifications on mammograms using mathematical morphology.

The top-hat and watershed algorithms of mathematical morphology have been applied to detect automatically and segment microcalcifications on mammograms digitized to a pixel resolution of 40 microns using a CCD camera. The database comprised 38 cases from the breast assessment clinic in Liverpool. For all cases, both craniocaudal (CC) and lateral oblique (LO) views were available. 19 cases were proven to be benign and 19 malignant based on cytology and histology. Malignant clusters contained more microcalcifications (14 malignant, 10 benign), occupied a larger area (37 mm2, 9 mm2) and had longer cluster perimeters than benign clusters (33.2 mm, 15.5 mm). Malignant microcalcifications exhibited a wider variety of shapes and were more heterogeneous in terms of image signal intensity than benign microcalcifications. Further mathematical morphology algorithms were applied to describe microcalcification shape in terms of the presence or absence of infoldings, elongation, narrow irregularities and wide irregularities. The three largest microcalcifications were selected for each case and, using a "leave-one-out" approach, each microcalcification was classified in respect of its five nearest neighbours as either malignant or benign. The area under the curve of a receiver operating characteristic (ROC) analysis of the proportion of the three microcalcifications which agreed with the true diagnosis increased from 0.73 (CC) and 0.63 (LO) to 0.79 when both views were considered. Next, each cluster in turn was ranked according to its agreement with the database as a whole over 21 features. An ROC analysis was performed to investigate the effect on sensitivity and specificity of the proportion of the nine nearest neighbours that agreed with the true classification. The largest area under the ROC curve was 0.84 produced by the four features of proportion of irregular microcalcifications, proportion of round microcalcifications, number of microcalcifications in the cluster and the interquartile range of microcalcification area. The shape of microcalcifications is confirmed as being of overriding importance in classifying cases as either malignant or benign. This observation motivates a further study enhanced by using magnified views digitized to a higher resolution by a laser scanner. This will enable the reliable assessment of the shape of a greater number of microcalcifications in each cluster, which is likely to increase further the discriminating power of the image analysis routines and lead to the development of an expert system for automatic mammographic screening.

Acro-osteolysis following snake and scorpion envenomation.

Three cases of acro-osteolysis are described following snake bite and three after scorpion stings. This effect is consistent with tissue necrosis secondary to the enzymatic actions of the venom.

Gall-bladder contraction and bile duct opacification in oral cholecystography--a comparison of different methods.

The effect of injection of a cholecystokinetic agent, Ceruletide, was compared with that of the fatty meal following a single dose of Biloptin, and Biloptin with Solubiloptin, in regard to efficiency of gall-bladder contraction, cystic and common bile duct visualisation and side effects. In terms of gall-bladder contraction and ductal delineation no advantage was found from giving Ceruletide or Solubiloptin. Gall-bladder contraction occurred more quickly after Ceruletide than after a fatty meal, with corresponding earlier duct delineation, although the gall bladder was completely emptied of contrast medium in a significant proportion of Ceruletide cases. The incidence of abdominal pain was significantly greater after Ceruletide than after a fatty meal. Because Ceruletide requires an intramuscular injection and has no significant advantage over the fatty meal in regard to gall-bladder contraction and ductal delineation, its use in cholecystography is unjustified. A morning dose of Solubiloptin following Biloptin the previous evening offers no advantage over the Biloptin and fatty meal regimen.

Discovertebral destruction in ankylosing spondylitis: the role of computed tomography and magnetic resonance imaging.

The computed tomography and magnetic resonance imaging appearances are described in five cases of ankylosing spondylitis with discovertebral destruction. Computed tomography revealed erosions of the vertebral bodies not visible on plain radiographs. The different appearances of the involved disc spaces on magnetic resonance imaging are described and their significance in relation to the pathology of this condition is discussed.

Calcification of the large bowel in schistosomiasis demonstrated by computed tomography.

Four cases are described in which large bowel calcification was demonstrated on CT. All four patients had mixed infection by Schistosoma haematobium and mansoni, the latter being responsible for this abnormality. Intestinal calcification by S. mansoni is unusual, but is especially well demonstrated by computed tomography.

The relationship between breast asymmetry, breast size and the occurrence of breast cancer.

Breast cancer is the second most common cancer among women in the world and in developed countries it is the most common. The early identification of women at risk is therefore of great importance and any additional measures which may aid diagnosis, particularly in high risk groups, would be of benefit. Breast volume and breast asymmetry were calculated from mammograms of 250 women with breast cancer and compared with those of 250 age-matched controls. There was evidence that breast cancer patients had more breast asymmetry and larger breasts than age-matched healthy women. The former observation is the first evidence that high breast asymmetry may be a risk factor for breast cancer. Breast asymmetry is likely to be a predictor of, rather than the effect of breast cancer.

Estimation of fetal volume by magnetic resonance imaging and stereology.

The current methods to monitor fetal growth in utero are based on ultrasound image measurements which, lacking a proper sampling methodology, may be biased to unknown degrees. The Cavalieri method of stereology guarantees the accurate estimation of the volume of an arbitrary object from a few systematic sections. Non-invasive scanning methods, and magnetic resonance imaging (MRI) in particular, are valuable tools to provide the necessary sections, and therefore offer interesting possibilities for unbiased quantification. This paper describes how to estimate fetal volume in utero with a coefficient of error of less than 5% in less than 5 min, from three or four properly sampled MRI scans. MRI was chosen because it does not use ionizing radiations on the one hand, and it offers a good image quality on the other. The impact of potential sources of bias such as fetal motion, chemical shift and partial voluming artefacts is discussed. The methods are illustrated on four subjects monitored between weeks 28 and 40 of gestation.

Estimation of breast volume and its variation during the menstrual cycle using MRI and stereology.

Unbiased estimates of breast volume may be obtained in vivo from systematic series of MR images acquired in accordance with the Cavalieri method of modern design-based stereology. The method does not require any assumptions to be made regarding breast shape. If point counting techniques are used to obtain the required breast section areas estimates, 10-15 min analysis (i.e. counting about 250 points on 12 to 16 images) ensures that the contribution of sectioning and point counting to the coefficient of error (CE) on the volume estimate is less than 3%. The methods were applied to measure breast volume in 15 healthy females aged between 22 and 44 years (mean 31.7 years; SD 8.2 years). One subject was studied on every fourth day during two consecutive cycles. The other 14 subjects were studied on three occasions corresponding to menses, ovulation and pre-menses during a single menstrual cycle. Repeat imaging after repositioning on three occasions within a period of 30 min and also at three different times of day for a single subject, both yielded a coefficient of variation (CV) of less than 3% in the estimation of breast volume. ANOVA indicates that there is no significant difference between the mean volume of the left and the right breast (p = 0.294). The mean volume of the left breast is 561 ml (95% confidence interval (CI): 553 ml, 569 ml) and the mean volume of the right breast is 567 ml (95% CI: 559 ml, 576 ml). There are highly significant differences between the three named stages of the menstrual cycle (p < 0.0005), whereby the mean volume at ovulation is 5.5% less than the mean volume at menses (95% CI: 3.0%, 7.9%) and the mean volume pre-menses is 8.1% greater than the mean volume at menses (95% CI: 5.3%, 10.9%). Overall, the volume of each breast varies by an average of 76 ml (95% CI: 61 ml, 92 ml) during the menstrual cycle, which corresponds to 13.6% of the volume at menses (95% CI: 13.3%, 13.8%). No significant interaction was found between the relative volumes of the left and right breast and the stage of the menstrual cycle (p = 0.277), nor between subjects and stages of cycle (p = 0.296). However, a significant interaction was observed between the volume of the left and right breasts in different subjects (p < 0.005). The average difference in the volume of the left and right breasts of all 15 subjects is 39.7 ml (95% CI: 21.3 ml, 58.1 ml), which is 7% of average breast volume and approximately 50% of the average variation in the volume of the breast during the menstrual cycle.