In vivo phosphorus magnetic resonance spectroscopy in multiple sclerosis.

Localized phosphorus magnetic resonance spectroscopy at 1.5 T was performed in 39 patients with multiple sclerosis and in 15 healthy controls. The multiple sclerosis spectra showed increased creatine phosphate levels. This increase was correlated with the severity of the handicap and was greater in patients with a progressive course of the disease than in patients with relapsing-remitting disease. No clear abnormalities were observed in the spectra of patients with multiple sclerosis regarding the phosphomonoesters, phosphodiesters, inorganic phosphate, and beta-adenosine triphosphate or with respect to pH values. There was an increased creatine phosphate level in the spectra in relation to a low metabolic state of the brain.

Noninvasive metabolic assessment of human donor livers: prognostic value of 31P-magnetic resonance spectroscopy for early graft function.

BACKGROUND: The purpose of this study was to investigate whether phosphorus-31 magnetic resonance spectroscopy (31P-MRS) of the isolated donor liver can serve as a viability indicator with prognostic value for transplantation outcome. METHODS: Forty human donor livers preserved with University of Wisconsin solution were studied shortly before transplantation. The respective spectral peak areas of the isolated donor liver were correlated with the amount of hepatocellular graft damage and liver metabolic function shortly after implantation. RESULTS: The individual phosphomonoesters, inorganic phosphate, phosphodiesters, and nicotine adenine dinucleotide peaks were not prognostic for postoperative hepatocellular damage or liver metabolic capacity. The presence of adenosine triphosphate, however, predicts a significantly better metabolic capacity to eliminate bilirubin, to synthesize fibrinogen and antithrombin III, and to maintain a better prothrombin time after transplantation. Furthermore, this study is probably the first 31P-MRS demonstration in the human liver of phosphocreatine. CONCLUSIONS: In the clinical setting described, metabolic assessment using 31P-MRS did not result in a reliable noninvasive test to predict primary graft dysfunction. Study of the role of phosphocreatine in liver metabolism during cold storage is needed.

The asymptomatic child a long time after the Mustard operation for transposition of the great arteries.

We studied 36 asymptomatic children 7.7 +/- 2.5 years after a Mustard operation. Fifteen children had sinus rhythm on all electrocardiograms made during follow-up. Only 2 had normal 24-hour Holter recordings throughout follow-up, 6 had periods of supraventricular tachycardia, and 3 had periods of atrial flutter. The electrophysiological evaluation of sinus node function was normal in 5 of the 31 children who were studied. The behavior of the atrial myocardium was electrophysiologically abnormal in most of the children. Atrioventricular node function, on the contrary, was normal in nearly all of the children. Eleven children had normal hemodynamics. Four had severe or complete obstruction of the superior vena cava, 1 had a severe pulmonary venous obstruction, 3 had a severe left ventricular outflow tract obstruction, and 2 had a large left-to-right shunt. Only 3 children had normal hemodynamic and electrophysiological studies. We conclude that the absence of symptoms and a normal routine examination of children a long time after a Mustard operation does not exclude hemodynamic and electrophysiological abnormalities, which can sometimes be severe. In view of these disappointing results, we decided to replace the Mustard operation with the arterial switch operation in children with transposition of the great arteries.

Magnetic resonance imaging of retroperitoneal lymph node metastases of non-seminomatous germ cell tumours of the testis.

The value of Magnetic Resonance Imaging (MRI) in the diagnosis, staging and treatment evaluation of retroperitoneal lymph node metastases of non-seminomatous germ cell tumours of the testis (NSGCT) was prospectively studied in 41 consecutive patients before, during and after cisplatin-based chemotherapy. MRI is a non-invasive method, with results equivalent to laparotomy in determining the anatomical localization and size of retroperitoneal lymph node metastases of non-seminomatous germ cell tumours of the testis and residual mass after chemotherapy. Components responding differently can be observed with MRI within the retroperitoneal lymph node metastases on the basis of the tumour signal intensity or homogeneity in the T1- and T2-weighted images; MRI cannot warrant any conclusion about viability of the residual mass or other effects of chemotherapy.

Pelvic girdle chondrosarcoma and inferior vena cava thrombosis.

Pelvic girdle chondrosarcomas in children and adolescents are extremely rare. These high grade malignant chondrosarcomas with a locally aggressive growth pattern have a high tendency for thrombus formations in the afferent tumour vessels, associated with an increased risk of inferior vena cava thrombosis, pulmonary embolism and metastatic spread to the lungs. This tumour location is generally non-resectable for cure and, since adjuvant chemotherapy is ineffective, patients die from the tumour thrombus formation causing tumour emboli and metastatic disease to the lungs. Effective local tumour control can be achieved with high-dose hyperfractionated radiation therapy.

MRI or CT in the preoperative diagnosis of bone tumours.

The value of magnetic resonance imaging (MRI) and computed tomography (CT) in the diagnosis of bone tumours was investigated in a prospective study of 25 patients. MRI is superior to CT because it permits multidirectional exposures. Moreover, the tumour can be readily distinguished from the neurovascular structures without injection of contrast medium. MRI gives better contrast than CT, making it possible to study the relationship to the soft tissues, bone marrow and joints more accurately. On the other hand, CT gives a better picture of the destruction of cortical bone. With neither MRI nor CT can the exact tumour length be measured. Neither MRI nor CT permits an exact, reliable diagnosis. Owing to the relatively slow exposure technique in combination with respiratory movements, depiction of the thoracic wall is less satisfactory with MRI than with CT. If both techniques are available, MRI is preferred. In view of the fact that MRI apparatus is still less widely available, it should be borne in mind that CT also allows an adequate investigation of skeletal lesions.

Magnetic resonance imaging (MRI) in evaluating in vivo response to neoadjuvant chemotherapy for osteosarcomas of the extremities.

Limb-saving procedures for patients with osteosarcomas of the extremities are based on the anatomical localization and extent of the tumor. The effectiveness of neoadjuvant chemotherapy, high-dose methotrexate (HD MTX), was prospectively analyzed in patients using magnetic resonance imaging (MRI) and histologic evaluation of bone biopsies. Evaluation of in vivo response to neoadjuvant chemotherapy for osteosarcomas with MRI is a method which seems promising in predicting the histologic tumor reaction.

Functional anatomy of the soft tissues of the hand and wrist: in vivo excursion measurement of the flexor pollicis longus-tendon using MRI.

Magnetic resonance imaging (MRI) of the flexor pollicis longus-tendon (FPL-tendon) with the thumb in different positions allows the in vivo assessment of its abduction-adduction/flexion excursion. Measurements can also be performed in different positions of the wrist. In our study, the mean excursion amplitudes of the FPL-tendon in seven healthy volunteers were 2.6 (+/- 0.26), 2.6 (+/- 0.25), and 2.7 (+/- 0.63) cm for neutral position, ulnar, and radial deviation of the wrist, respectively. The contribution of the abduction-neutral position route and the neutral position-adduction/flexion route to the total excursion of the thumb varied for the different positions of the wrist, despite the equal excursion amplitudes. The possibility of visualization and the accurate determination of the FPL-tendon excursions is of use in the reconstruction and the transposition of the FPL-tendon. In addition, the shift of the FPL-tendon can be visualized for different positions of the thumb and the wrist.

On the relation between the dimensions and resonance characteristics of the vocal tract: a study with MRI.

The relation between the spatial configuration of the vocal tract as determined by magnetic resonance imaging (MRI) and the acoustical signal produced was investigated. A male subject carried out a set of phonatory tasks, comprising the utterance of the sustained vowels /i/ and /a/, each in a single articulation, and the vowel /epsilon/ with his larynx positioned variously on a vertical axis. Two- and three-dimensional measurements of the vocal tract were performed. The results of these measurements were used to calculate resonance frequencies, according to predictions from acoustical theory. Finally, calculated frequencies were compared with actually measured resonance frequencies in the audio signal. We found a strong relation between the acoustical signal produced and the spatial configuration for the first resonance frequencies of the articulations of the vowel /epsilon/, and first two resonance frequencies of the vowels /a/ and /i/. The capability to determine accurately vocal tract dimensions is a major advantage of this imaging technique.

Ex vivo MRI in extracorporeal liver surgery.

Extracorporeal resection of hepatic tumors that were considered inoperable in the past is now possible in selected cases. Such procedures require high-quality preoperative images for the exact delineation of the tumor extent and for an optimal planning of the line of parenchymal division. In-vivo CT and MRI can not always depict the tumor adequately. In such cases, ex-vivo MRI may be a useful additional technique. It combines a high spatial resolution with the best possible soft tissue contrast, as was learned from previous studies on donor livers destined for transplantation. Ex-vivo MRI favours both a sufficiently radical resection as well as sufficient hepatic functional reserve to be present for reimplantation. A case history is reported together with details on the technical procedure.

Abdominal applications of fast MR imaging: a comparison of fast field echo (FFE) and spin echo (SE) pulse sequences.

Fast gradient echo (GE) MR imaging during breathhold was performed in 73 abdominal MR examinations in order to determine the value of GE technique in the reduction of movement artefacts and improvement of image quality. The results were compared with conventional spin-echo (SE) technique. T1-weighted SE images consistently demonstrated normal anatomy and pathology. T2*-weighted and intermediate GE technique proved to be superior to T2-weighted SE technique in a considerable number of cases providing not only better delineation of normal structures but also better lesion detection. At this stage GE technique should be considered as an adjunct to T1-weighted SE technique. If the artefacts presently inherent to GE imaging could be reduced or compensated for, this technique of rapid MR imaging during suspended respiration could become an important tool being one of the fastest techniques for abdominal MR imaging.

DSA--a helpful tool in diagnosis of aberrant left pulmonary artery (vascular sling) in adults.

Two new adult patients with aberrant origin of the left pulmonary artery from the right pulmonary artery--pulmonary artery sling--are described, totalling the published adult cases to eight. Differentiation from a mediastinal mass closely mimicking this vascular anomaly is discussed. For the definitive diagnosis, digital subtraction angiography was applied for the first time. The clearest demonstration of the anatomy is in 20-25 degrees RPO and 20-25 degrees sitting position. The aberrant left pulmonary artery in adults is asymptomatic.

The role of magnetic resonance imaging and computed tomography in the treatment evaluation of retroperitoneal lymph-node metastases of non-seminomatous testicular tumors.

The role of Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) in the treatment evaluation of retroperitoneal lymph-node metastases of non-seminomatous testicular tumors (NSTT) was prospectively studied in 10 consecutive patients before, during and after chemotherapy. The results thus obtained were compared with laparotomy findings before and after chemotherapy, the histology of the primary testicular tumor, and that of retroperitoneal residual lesions after chemotherapy. MRI and CT proved to be equivalent in detection and in determining the anatomical localization and size of the retroperitoneal lymph node metastases. Unlike CT, MRI revealed unmistakable changes in the structure of the retroperitoneal lymph-node metastases during chemotherapy, for which no histological cause was found except in mature teratoma. In mature teratoma a high T2 signal was found within the metastases, corresponding with a high water content. On the basis of tumor consistency and signal intensity in the T1- and T2-weighted images, MRI cannot yet warrant any conclusion about the ultimate effect of chemotherapy.

Interaction of metallic neurosurgical implants with magnetic resonance imaging at 1.5 Tesla as a cause of image distortion and of hazardous movement of the implant.

Metallic implants used in neurosurgery, comprising vascular clips, shunt valves, and metallic surgical wire for spondylodesis, induce distortion of magnetic resonance images. The image deformation usually pertains to small areas of signal suppression in its immediate vicinity, when the implant is non-ferromagnetic. The image deformation is more pronounced when the implant is ferromagnetic, but more important, as is the case with some strongly ferromagnetic aneurysm clips, the magnetic field may cause movement of the clip. Therefore, it is advisable to refrain from magnetic resonance imaging in patients harbouring intracranial aneurysm clips, as the movement in the magnetic field may be hazardous.

Quantification of liver iron concentration with magnetic resonance imaging by combining T1-, T2-weighted spin echo sequences and a gradient echo sequence.

BACKGROUND: The aim of the study was to quantify hepatic iron by MRI for practical use. METHODS: In twenty-three patients with various degrees of iron overload, measurements were carried out with a 1.5 Tesla MR unit. A combination of pulse sequences (T1, T2 and gradient echo) enabled us to quantify smaller amounts of liver iron as accurately as larger amounts of liver iron. The gradient echo sequence provided us with a good correlation when detecting smaller amounts of iron in the liver where the T1 sequence provided a good correlation when larger amounts of iron were present. RESULTS: The combination of the three sequences showed a nice correlation (r=-0. 93, P<0.001) and provided us with an accurate estimate of the liver iron content (LIC). This correlation was achieved with a LIC from the lower range of normal up to LIC of 146 mmol/kg dry weight, which seems the highest measurable liver iron content for a 1.5 Tesla MRI. Measuring in the lower range makes it possible to decide whether further invasive diagnostic investigations by a liver biopsy are indicated. CONCLUSION: MRI is a useful tool to quantify iron overload non-invasively. In cases where a liver biopsy is hazardous MRI can easily be used to obtain reliable, quantitative information about the initial LIC. Quantification by MRI could also be used for follow up of the iron content during depletion treatment by phlebotomy or iron chelation. The stronger the magnet the more sensitive the detection of concentrations up to 150 mmol/kg is. A semi-quantitative judgement will only be possible with severe iron overload over 150 mmol/kg. If such an iron excess is found, a liver biopsy should be performed to exclude cirrhosis.

Magnetic resonance imaging using a clinical whole body system: an introduction to a useful technique in small animal experiments.

A clinical whole body magnetic resonance imaging (MRI) system with high resolution coils was used to obtain non-invasive images of the living rat. The results demonstrate the feasibility of the set-up and the advantages of this new imaging technique: detailed information, no extra costs, longitudinal studies without killing animals and simple anaesthesia. It is concluded that in small animal experimentation, this use of high resolution coils in whole body magnetic resonance systems may be particularly helpful in establishing effects of experimental procedures. Whenever non-invasive visualization is required, especially in longitudinal animal studies, e.g. biomaterial research or tumour investigation, this use of MRI will offer challenging possibilities.

[Value of proton spin tomography in the diagnosis of intra-articular pathological disorders of the knee]. / De waarde van kernspinresonantie-tomografie bij de diagnostiek van intra-articulaire pathologische afwijkingen van de knie.

Magnetic resonance imaging (MRI) of the knee was performed in 50 patients with unilateral knee problems with clinical suspicion of a meniscal tear or degeneration of the cartilage. The findings of the MRI examination were compared with previously performed arthrography and the diagnosis was subsequent confirmed arthroscopically. MRI detected degenerative changes in 69 out of 100 menisci and signs of a meniscal tear in 31 of the menisci. The diagnostic accuracy of MRI for a tear in the medial or the lateral meniscus was 91%. MRI was accurate in the detection of 8/11 ruptures of the anterior cruciate ligament and in 6/13 cases with degenerative changes of the patella.

[A swelling in the distal part of the thigh]. / Een zwelling distaal in het bovenbeen.

A swelling in the distal thigh may be caused by a tumour of bone or soft tissues, an aneurysm or an inflammation. Signs of inflammation may render interpretation more difficult. Four males aged 60, 48, 15 and 81 years had had a swelling in the popliteal space or above the knee, in some cases with pain. Supplementary examinations, especially MRI scanning and arteriography did not always result in a diagnosis. The diagnosis could be made, however, during operation: an empyemic thrombosed popliteal artery aneurysm, a liposarcoma, pyomyositis and suture dehiscence of a plastic prosthesis of the popliteal artery. After treatment, consisting of or started during the operation, uneventful recovery occurred.

Giant rhabdomyoma of the right ventricle.

A giant intrathoracic mass causing foetal dysrhythmias, polyhydramnios and foetal hydrops necessitated a caesarean section in a male infant of 35 weeks gestation. Despite the benign histology of cardiac rhabdomyomas and the observation of spontaneous regression, there may be significant associated morbidity and mortality, especially in neonates. There is a high incidence of associated tuberous sclerosis.

[Magnetic resonance imaging. Principles and applications in the head and neck area]. / Magnetic resonance imaging. Principes en enkele toepassingen in het hoofd-halsgebied.

Magnetic Resonance Imaging is one of the most recently developed imaging techniques of the human body. In this review the physical principles and applications for oral surgeons are discussed.