Functional variations in the ultrastructure of the thyroid gland in malnourished infant monkeys.

Healthy male pigtail monkeys (Macaca nemestrina) were procured at the age of 6-9 months, and fed either a 20 percent casein diet or a diet containing 2 percent casein as the sole source of protein. After 3-5 months, the malnourished monkeys developed many features usually associated with the clinical syndrome of marasmic kwashiorkor as seen in socioeconomically underpriviledged societies. Ultrastructural evaluation of thyroid gland revealed that dietary protein-calorie deficiency produced marked reduction in follicular cell height, conspicuous decrease in the number of apical filamentous microvilli, and a relative scarcity of the apical microvesicles as well as other pale staining colloid vesicles compared to findings on control glands. The electron-dense lysosomelike granules did not appear particularly affected, although in some sections they seemed to have increased in number and were located mainly in the basal portion of the cells, These electron-dense granules often displayed marked lack of homogeneity in regard to their structure in the malnourished glands. Most of these morphologic alterations have been noted frequently in thyroid glands of hypophysectomized animals, or in glands suppressed by the administration of thyroxine, and are therefore highly indicative of thyroid hypofuction in this animal prototype of human protein-calorie malnutrition.

Progressive effects of protein-calorie malnutrition on serum free amino acids in infant and young adult nonhuman primates.

Serum amino acid profiles have been known to change when dietary protein restriction is instituted in animals and in man. In the present study, significant alterations were noted in infant monkeys observed over 14 weeks. Impressive but less dramatic changes were apparent in protein-restricted young adult monkeys observed over a much longer period. In general, essential amino acids were depressed (especially the branched-chain group) while nonessential amino acids tended to rise (especially glycine and alanine). Changes were most acute within the first 3 to 4 weeks of dietary restriction. Improvement in dietary protein content provided to young adults led to resumption of normal serum amino acid patterns. Level of available dietary protein and age of the animals clearly dictated the severity of amino acid imbalance observed.

In utero perfusing fraction maps in normal and growth restricted pregnancy measured using IVIM echo-planar MRI.

The aim of this study was to measure and portray blood movement in the placenta in vivo in normal and growth restricted pregnancies, using Intra Voxel Incoherent Motion (IVIM) magnetic resonance imaging. Thirteen patients with apparently normal healthy pregnancies were scanned at 31+/-7 (mean+/-s.d.) weeks gestation and seven patients with intrauterine growth restriction (IUGR) were scanned at 31+/-4 weeks. A region of interest (ROI) was defined encompassing the placenta between the decidual and chorionic plates. The volume of moving blood within each imaging voxel of the ROI was then calculated as a percentage of the total voxel volume (f per cent). This information was colour coded to produce maps of moving blood volume. The placenta was segmented length ways into two zones of approximately equal area, termed inner and outer, the latter being adjacent to the uterine wall. f was fitted for the average in the outer zone (f(out)) and inner zone (f(in)). The parameter (f(out)-f(in)) was then calculated for each subject. This was positive in 12/13 of the normal cases and zero for one case (+10 per cent+10, mean+/-s.d.). For pregnancy affected by IUGR this value was negative in all cases (-4 per cent+/-3). Perfusion fraction mapping identified differences in function within the normal placenta in vivo, and between the placentae of normal and IUGR pregnancies. The technique has potential applications in managing, and investigating the aetiology of, pregnancy compromise.

NMR tissue characterization in intracranial tumors: preliminary results.

Nuclear magnetic resonance (NMR) has been shown to have high sensitivity for detecting intracranial pathology. A study was devised to determine what information about tissue characteristics can be derived from steady-state free-precession NMR images alone and when compared with computed tomographic (CT) scans. The flow-dependent sequences allow diagnosis of intrinsic vascular lesions. Whereas precise characterization of some pathologic groups such as fat-containing tumors is possible, other important groups cannot be clearly differentiated. Preliminary findings suggest that it may be possible to predict the texture of extrinsic tumors from their NMR signals.

The role of NMR imaging in the diagnosis and management of acoustic neuroma.

Nuclear magnetic resonance (NMR) scans of 15 patients with acoustic neuroma are compared with the results of computed tomography (CT). The absence of signal from bone has meant that the images are unaffected by artifacts and that small intracanalicular tumors can be visualized. The multiplanar facility of NMR is emphasized as this allows precise assessment of both tumor volume and its relationship to the ventricular system, brainstem, and tentorial hiatus. The different appearances produced by alternative scan sequences are illustrated and the possibility of predicting the physical constitution from scan appearances is discussed.

Craniovertebral junction pathology: assessment by NMR.

In nuclear magnetic resonance (NMR) studies choice of imaging plane is achieved by a variety of methods that restrict data collection to the desired region. This means that the additional perspectives of direct sagittal and coronal views are possible. In sections traversing the brainstem and cervical cord the neural tissue is clearly seen contrasted against the surrounding cerebrospinal fluid (CSF). NMR studies of a wide variety of lesions in the vicinity of the craniovertebral junction, including congenital and acquired bony deformities, intrinsic tumors, and syringomyelia, are evaluated. It is concluded that the assessment of clinical problems involving this region is simplified by NMR imaging and that its use will probably allow more invasive procedures to be avoided.

The application of NMR imaging to the evaluation of pituitary and juxtasellar tumors.

Nuclear magnetic resonance (NMR) imaging was used to evaluate pituitary and juxtasellar tumors in 37 patients representing a wide range of pathology. The value of the multiplanar facility of NMR is emphasized in providing accurate volumetric information and establishing the topographical relation of tumors to adjacent structures. Current limitations of the method and possible future developments to improve diagnostic precision are discussed.

NMR imaging in the evaluation of orbital tumors.

The application of nuclear magnetic resonance (NMR) imaging to the diagnosis of orbital space-occupying lesions was studied in group of 28 patients with a wide range of pathology. The NMR findings in six patients are illustrated. The results of the NMR scans are compared with the information that can be derived from conventional neuroradiologic procedures, including computed tomography. The value of the multiplanar facility of NMR is emphasized. It provides accurate volumetric information and establishes the precise topographical relationships of tumors to normal structures. The muscle cone and the optic nerve can be identified in the axial, coronal, and sagittal planes. Current limitations of the method and possible future developments to improve diagnostic precision are discussed.

Extracerebral collections: recognition by NMR imaging.

After head injury, nuclear magnetic resonance (NMR) scanning is, like computed tomography (CT), an effective method of distinguishing between intracerebral and extracerebral lesions. The location and shape of extracerebral collections are excellently displayed using the multiplanar facility of NMR. There are good grounds for believing that the problem of the isodense subdural hematoma encountered in CT scanning can almost certainly be overcome by the use of NMR imaging.

NMR imaging in the recognition of giant intracranial aneurysms.

Most giant aneurysms present clinically as intracranial mass lesions. Many contain an organized lamellated thrombus with only a small eccentric lumen remaining that can be opacified at angiography. Four patients with such aneurysms were studied using flow-dependent nuclear magnetic resonance scanning sequences. The aneurysms show a smooth rounded margin, and the thrombus within is clearly distinguishable from the blood flowing through the patent lumen, which gives a low signal. By using different scan sequences it is possible to prove that the area of low signal is indeed fluid in rapid motion, thus confirming the diagnosis.

NMR imaging in the diagnosis and management of intracranial angiomas.

Fourteen intracranial angiomas were clearly visualized and diagnosed with certainty on fast saturation-recovery images, which highlight blood vessels without the use of contrast media, and on steady-state free-precession images, in which the moving blood leads to removal of signal. Performed as the initial investigation, nuclear magnetic resonance obviates angiography when the site and extent of the angioma would preclude operation, and in other cases provides useful anatomic information complementing the angiogram. When clinical presentation follows hemorrhage the size and position of the associated hematoma can be reliably assessed.

In vivo relaxation time measurements in the human placenta using echo planar imaging at 0.5 T.

This paper presents the first in vivo measurements of the nuclear magnetic resonance relaxation times T1 and T2 at 0.5 T in the human placenta from 20 weeks gestational age until term, in both normal and compromised pregnancies. T1 measurements were performed by using both an inversion recovery sequence and the Look-Locher echo planar imaging (EPI) sequence on a total of 41 women with normal pregnancies and 11 women with compromised pregnancies. T2 measurements were performed by using a spin-echo EPI sequence on 36 women with normal pregnancies and 14 women with compromised pregnancies. In normal pregnancies, both the T1 values measured with the inversion recovery sequence and the T2 values were found to decrease with gestational age, the linear regression results gave T1 = -9.1t + 1538 r2 = 0.23 p = 0.03. T2 = -4.0t + 338 r2=0.47 p =410(-6) where t is the gestational age in weeks, and T1 and T2 are the relaxation times in milliseconds. T1 values measured very rapidly with the Look-Locher EPI sequence, but, therefore, with a much lower signal-to-noise ratio, showed no significant trends. The T1 values measured in the abnormal group were significantly lower than those measured in the normal group. Four out of eight patients with compromised pregnancies had placental T1 values lying outside the 90% confidence limits for the normal population based about the regression line, significantly more than expected by chance (p = 0.005). Ten out of fourteen of the T2 measurements in the abnormal group were below the regression line established for the normal group, with 4 lying below the 90% confidence interval, although these trends were only just significant (p = 0.06 and p = 0.03).

Magnetic resonance imaging of spinal trauma.

A retrospective series of 118 magnetic resonance examinations of 110 patients who had sustained previous spinal trauma is reported. Examinations performed within 3 weeks of trauma showed extraspinal soft tissue (including ligamentous) injury in 48% and intraspinal lesions in 61% (mostly consisting of extradural haematoma and spinal cord contusion). In examinations performed more than 3 weeks after injury intraspinal abnormalities were shown in 51% and these represented spinal cord compression, atrophy, myelomalacia and syringohydromyelia. Magnetic resonance imaging has the unique capability of displaying non-invasively the late sequelae of spinal trauma permitting simultaneous evaluation of the extra-spinal soft tissues, vertebral column and spinal cord. It is therefore recommended as the technique of choice in the investigation of patients who have sustained previous spinal injury, particularly those with neurological deficit. In the acute phase potentially remediable causes of neurological impairment such as disc herniation or extradural haematoma can be identified. Signal changes in the cord may allow the prognosis for neurological recovery to be established. In the later stages sequelae such as cord atrophy, myelomalacia and syringohydromyelia are accurately identified and surgical therapy may be guided, where appropriate.

A comparative study of magnetic resonance imaging and computed tomography-assisted myelography in spinal dysraphism.

Thirty-seven patients with a wide spectrum of spinal dysraphic lesions were studied by both magnetic resonance imaging (MRI) and myelography complemented by computed tomography (CT). Magnetic resonance imaging proved to be superior for tissue characterization, overall anatomical definition, topographical relationships of the cranio-cervical junction and demonstration of the presence and extent of hydrosyringomyelia. Demonstration by CT myelography of fine neural structures such as the filum terminale and nerve roots remains the superior technique; however, with constantly improving spatial resolution and thinner-slice imaging, MRI will become increasingly competitive in this respect. The osseous component of these lesions was best demonstrated by CT myelography. A high incidence of associated syrinx (8/15 cases) was found in the diastematomyelia group, with an overall incidence of 15 cases in all the dysraphic patients studied. The use of both T1- and T2-weighted sequences is required for tissue characterization. Whilst both imaging modalities proved complementary in the investigation of spinal dysraphism, we suggest that, with its superior tissue characterization and anatomical display of these lesions. MRI should be the primary imaging technique. Avoidance of an invasive procedure and use of ionizing radiation confers additional benefits upon MRI. The relative ease and shorter examination time of MRI makes this technique ideal for pre- and post-operative monitoring and assessment.

Magnetic resonance imaging and hydatidiform mole.

Five women with complete and partial hydatidiform mole were examined by magnetic resonance imaging (MRI). Spin-echo pulse sequences (T2 weighted) were found to provide excellent resolution, while inversion-recovery pulse sequences (T1 weighted) gave better pathological detail. The myometrium was clearly seen on each patient and no invasion by the tumour detected. This corresponded to the histological findings. The potential uses of magnetic resonance in the diagnosis of primary and recurrent trophoblastic disease and its role in management are discussed.

Magnetic resonance imaging of the cerebello-pontine angle.

A variety of extra-axial lesions occurring at the cerebello-pontine angle was examined by magnetic resonance imaging (MRI). Differences in spin sequence characteristics were found between neurilemmomas and meningiomas, with neurilemmomas exhibiting a greater increase in T2 than meningiomas. The T1 images were of less value in differentiating between neurilemmomas and meningiomas but were of value in the diagnosis of vascular lesions, due to the decreased T1 of blood clot. The T1 images were also of value in the assessment of tumour size and in the diagnosis of an epidermoid cyst. Extension of tumour into the internal auditory meatus was seen on MRI with acoustic neuromas and with one other lesion. The transverse perspective was of greatest value in lesion assessment. The coronal perspective was useful in certain situations but the sagittal perspective was of minimal clinical value.

Computer aids to mammographic diagnosis.

The improvement of mammographic specificity was investigated by means of identifying specific radiological features. Data are presented on the first 500 patients studied who had previously undergone mammography followed by biopsy. The presence of specific mammographic features on each radiograph, first determined by retrospective examination, was entered into a computer database. Subsequent discriminant function analysis demonstrated the importance of a small number of features whose presence could be used in an algorithm to predict diagnostic outcome. Using this algorithm, this feature-identification approach correctly identified 87.6% of benign and 79% of malignant cases. Specificity was improved to 88% as compared with the original radiological diagnosis of 49%. It is argued that this approach is very promising and a computer-assisted diagnosis based on these findings is described.

Gadolinium-enhanced magnetic resonance imaging of spinal tumours.

The use of gadolinium diethylenetriamine-penta-acetic acid (Gd-DTPA) (Magnevist) enhanced magnetic resonance imaging (0.15 T) in the assessment of spinal tumours is described. Thirty-five patients were entered into the study and a total of 39 examinations were performed. The information obtained from unenhanced T1- and T2-weighted spin-echo sequences was compared with the Gd-DTPA-enhanced T1 images. Thirty patients had intradural lesions and five had extradural lesions. A variable pattern of enhancement of intramedullary tumours was found, which in part reflected differences in the cystic component of the lesions. Extramedullary intra- and extradural lesions generally showed marked enhancement. The greatest contribution to management decisions was in the evaluation of intramedullary tumours where the use of contrast enhancement facilitated the precise localization of active tumour, differentiation of cystic and solid components of tumour, separation of tumour from peritumoral oedema and, in cases of suspected recurrence, aided distinction between tumour and both post-operative scarring and radiation damage.

Review article: computed tomography and magnetic resonance in the diagnosis of intraventricular cerebral masses.

We describe a series of 60 cases of patients with masses arising within the cerebral ventricles. The site and relative frequency is noted for each histological type. The differential diagnosis depends on patient age and sex, site, morphology and number of masses, presence and type of hydrocephalus and the characteristics of the mass on computed tomography (CT) and magnetic resonance (MR) images. A review of the literature has been performed and this information collated with our own experience to give detailed descriptions of the typical features of each intraventricular mass. Attention is drawn to intraventricular neurocytoma, a recently described tumour that may be mistaken histologically for intraventricular oligodendroglioma or ependymoma. A comparison is made of the value of CT and MR in the diagnosis of intraventricular masses.

Magnetic resonance imaging of benign ovarian masses.

Forty-one patients with 45 pelvic mass lesions were assessed by magnetic resonance imaging (MRI). All lesions were initially considered to be benign ovarian masses with this diagnosis confirmed in 36 lesions. The characteristics on MRI are analysed and features useful in predicting histological type identified. Our results indicate that a high, though not absolute, level of diagnostic specificity should be obtainable in identification of ovarian pathology.