[Volume selective 31P NMR spectroscopy for differentiation of graph rejection and acute tubular necrosis after kidney transplantation]

Volume-selective 31P-MR spectra were obtained from 37 patients using a whole-body MR scanner in combination with surface coils and a modified ISIS sequence. The quantitative evaluation took place by line fitting to the signal in the time domain using a non-linear procedure. The following signal intensities were determined: PME, PDE, Pi, gamma-, alpha-, beta-ATP and pH. 1024 excitations were averaged to achieve an adequate signal-to-noise ratio (10.0 +/- 3.3), measurements lasting 34 minutes on average. The mean measured volume was 174 +/- 52.4 ml. Contamination by muscle tissue could be excluded based on the absence of phosphocreatinine signal in the spectra. Contamination by fatty tissue was excluded by visualisation. A reduction in the value of the Pi/alpha-ATP ratio as a function of time was observed due to the regeneration process following reperfusion injury. In transplant rejection (n = 7) a significant rise in Pi/alpha-ATP ratio was seen compared to the control group (n = 20) (0.4 +/- 0.16 vs. 0.22 +/- 0.11, p < 0.01), the calculated difference in pH was significant as well. In cases of acute tubular necrosis a reduced value fore the PME/PDE ratio was observed (0.65 +/- 0.1 vs. 0.96 +/- 0.5, p < 0.04). Acute tubular necrosis could be differentiated from rejection by difference in pH (6.93 +/- 0.1 vs. 7.14 +/- 0.19, p < 0.04).

[Localization of puncture needles in MRI: experimental studies on precision using spin-echo sequences at 1.0 T]

PURPOSE

To evaluate accuracy of needle localisation using and signal enhancement on a 1.OT MR imager for various needles for MR-guided biopsy.

METHODS

The differences between actual and virtual needle position of needles with different orientations were evaluated in a phantom for spin-echo including turbo-spin-echo sequences.

RESULTS

Artifacts depended on the orientation of the needle relative to the field B0, frequency-encoding gradients (Gf) and slice orientation. This resulted in different artifact shapes and sizes for left or right and cranial or caudal biopsy access routes. Applying turbo spin echo sequences feasible for biopsy, the signal void of a 18 G needle (Cook) parallel to Gf reached between 0.3 and. 4.6 mm further into the medium than the real needle tip, depending on needle orientation relative to B0. The diameter of the signal void around the needle varied, the needle shaft was right in the centre of the signal void. With Gf orthogonal to the needle the offset of signal void to needle tip ranged from 2.7 to 3.3 mm, while the actual position of the needle shaft was up to 3.3 mm lateral of the signal void center. While nominal echo times did not influence the size of the artifact in turbo-spin-echo sequences, the artifacts increased with smaller matrix and larger water-fat shift. Material and mass of the needle determined the size of the artifacts as well.

CONCLUSION

Localisation accuracy of the needle can be optimised by choosing optimal gradient directions depending on whether needle tip or shaft position should be displayed.

MR sialography: initial experience using a T2-weighted fast SE sequence

PURPOSE

The aim of this study was to evaluate an MR technique optimized for imaging of the parotid gland ductal system.

METHOD

The pulse sequence was optimized in 10 volunteers to depict static or nearly static fluid in the parotid ductal system. A heavily T2-weighted fast SE sequence (TR 3,600 ms/TE 800 ms) with a slice thickness of 30-40 mm using an 8 cm surface coil allowed depiction of the fluid-filled parotid duct. Thirteen patients with benign as well as malignant parotid gland pathologies were examined: sialadenitis (n = 2), sialadenosis (n = 3), Heerfordt syndrome (n = 1), pleomorphic adenoma (n = 2), parotid carcinoma (n = 1), lymphoepithelial carcinoma (n = 1), cystadenolymphoma (n = 2), and non-Hodgkin lymphoma (n = 1).

RESULTS

The heavily T2-weighted projection image yielded good quality sialographic images. The main duct and primary branching ducts were clearly depicted in all normal cases. The main duct was visualized in all patients. Intra- and extraglandular duct widening and ductal strictures were well depicted. Sialolithiasis with a calculus in the main duct was correctly demonstrated in one case.

CONCLUSION

MR sialography is noninvasive and does not depend on duct cannulation or contrast agent injection. Initial experience with a thick slice projection technique indicates that MR sialography can be successfully applied to image the parotid gland ductal system.

Localized 31P MR spectroscopy of the transplanted human kidney in situ shows altered metabolism in rejection and acute tubular necrosis

The purpose of this study was to investigate the function of transplant kidneys in situ, and to detect pathologic changes, using volume-selective phosphorous NMR spectroscopy (31P MRS). Localized 31P MR spectra were obtained from 37 patients using a whole-body MR scanner with a combination of surface coils, adiabatic excitation pulses, and a modified image-selected in vivo spectroscopy (ISIS) sequence. Seventeen patients with pathologic changes after renal transplant were compared with a control group of 20 patients with no evidence of transplant dysfunction. The transplant kidneys with rejection reaction showed higher ratios of inorganic phosphate (P2i) to adenosine triphosphate-alpha (ATP-alpha) than the normal control group (.4 +/- .16 compared with .22 +/- .11, P = .01) and reduced pH. The spectra of transplant kidneys with tubular necrosis had lower phosphomonoester (PME)/phosphodiester (PDE) ratios than the control group (.65 +/- .35 compared with .96 +/- .5, P = .04). The pathologies of rejection and tubular necrosis could be differentiated from each other by pH (6.93 +/- .1 in rejection versus 7.14 +/- .19 in tubular necrosis, P = .04). Preliminary results indicate that localized image-guided 31P MR spectroscopy of transplant kidneys in situ can detect rejection reactions and acute tubular necrosis noninvasively, providing an incentive for further research.

[31P-MR spectroscopy of the human liver--the spectral indications of lymphoma infiltration]

PURPOSE

To evaluate whether phosphorus magnetic resonance spectroscopy (31P-MRS) enables a non-invasive detection of liver involvement in systemic diseases like Hodgkin's lymphoma.

MATERIALS AND METHODS

Using a clinical 1.5 Tesla whole-body MR system image-guided localised phosphorus MR spectra from the anatomically defined volumes of interests were measured. A combination of surface coil, adiabatic excitation pulse and modified image-selected in vivo spectroscopy (ISIS)-sequence was applied. The spectroscopy data were evaluated quantitatively with a time-domain fit programme using non-linear optimisation algorithms to quantify peak areas. After establishment of the examination protocol, 22 healthy volunteers and 13 patients with suspected lymphoma infiltration of the liver were examined.

RESULTS

Liver spectra of patients suffering from lymphoma infiltration differed significantly from spectra of persons with normal liver: 1. The peak area ratio of phosphomonoesters (PME) to beta-NTP was elevated in all patients with histologically confirmed liver lymphoma. 2. Patients suffering from Hodgkin's disease with specific or unspecific liver infiltration (n = 7) could be differentiated from patients without liver involvement. In case of infiltrated liver, the peak area ratio PME to beta-NTP was increased, and the pH value was shifted to lower values. Unambiguous differentiation between non-specific (n = 3) and specific (n = 4) infiltration of the liver was not possible. 3. In patients after cytostatic treatment (n = 3), an increase of the peak area ratio of inorganic phosphate to beta-NTP was observed.

CONCLUSIONS

Our preliminary results indicate that 31P-MRS can yield pointers to liver involvement in patients with systemic diseases such as Hodgkin's disease, which may be hardly detected by imaging methods.

Nontraumatic subarachnoid hemorrhage: value of repeat angiography

PURPOSE

To evaluate the benefits and risks of repeat cerebral angiography in patients with subarachnoid hemorrhage of unknown cause.

MATERIALS AND METHODS

Findings from 391 angiographic examinations (323 initial, 68 repeat) were retrospectively reviewed in 323 patients with nontraumatic subarachnoid hemorrhage to determine the cause of bleeding and the frequency of complications with neurologic deficit.

RESULTS

At the initial angiographic examination, aneurysms were found in 195 patients (60.4%), and arteriovenous malformations were found in 11 patients (3.4%). Sixty-six patients with negative findings at initial examination underwent repeat cerebral angiography. Three additional aneurysms were detected, all of which could be seen retrospectively on the initial angiogram. In 63 patients, the cause of bleeding remained unexplained. Complications of the 391 angiographic examinations were definitive neurologic deficits in one patient (0.2%) and transient deficits in seven patients (1.8%).

CONCLUSION

Repeat angiography is not necessary in patients with subarachnoid hemorrhage if technically good, carefully evaluated digital subtraction angiography was performed initially. Repeat angiography seems to be justified only when the initial examination is technically inadequate, when vasospasm is present, or if further bleeding occurs.

CT and MR imaging in primary cerebral non-Hodgkin's lymphoma

PURPOSE

To determine the morphological appearance and topographical distribution of primary cerebral non-Hodgkin's lymphoma (NHL).

MATERIAL AND METHODS

CT and MR examinations of 68 patients with primary cerebral NHL were analyzed. The NHLs were classified by the Kiel classification and immunohistological data, as centroblastic (25), immunoblastic (24), lymphoblastic (5), Burkitt (1), non-subclassifiable type B (11), and T-cell lymphoma (2).

RESULTS

Centroblastic lymphomas tended to predominate in the parietal lobe (56.5%) and the corpus callosum (59.1%) while immunoblastic lymphomas were mainly distributed in the frontal lobe (52.8%). About 2/3 of all NHLs showed a multifocal occurrence. Important for differential diagnosis, ventricular involvement was proved in 83.3% of these cases. In the remaining 26 patients with a solitary lymphoma, a periventricular location could be detected in only 8 cases. Central necroses were frequent in HIV-positive patients (7/11, 63.6%) but rare in the HIV-negative patients (9/57, 15.8%). On T2-weighted SE MR images, 8/11 centroblastic lymphomas gave a signal that was isointense with, or lower than, that of the contralateral white matter, while 8/10 immunoblastic lymphomas gave a higher signal.

CONCLUSION

The radiological finding of multifocal brain lesions with ventricular involvement is relatively specific for primary cerebral NHL. However, subclassification on the basis of the CT or MR imaging results is not yet possible.

[Injuries of the spine: current concepts in radiologic diagnosis]

This review discusses the usefulness of plain radiography, computed tomography (CT), and magnetic resonance imaging (MRI) in the evaluation of spinal trauma. The indications for the different imaging modalities in dependence on the specific pattern of injury are explored. Plain radiography still remains the prime method in the diagnosis of acute spinal trauma but there are substantial deficits, especially in the evaluation of the occipitocervical and the cervicothoracic junction as well as in the evaluation of the integrity of the posterior vertebral body line. If injury in these regions is suspected CT should follow plain radiography immediately. In the case of spinal trauma with unexplained neurologic deficits MRI is the method of choice for the detection of spinal cord injury. Recommendations with regard to instability and the classification of specific injuries, including examples of typical findings are presented.

Late results after resection of benign hepatic tumors: clinical and radiological findings

The purpose of our work was to provide data on the recurrence of resected benign hepatic lesions and to evaluate the value of follow-up examinations in this group of patients. From August to October 1993, 75 patients who had been admitted for liver surgery for benign tumors between 1975 and 1993 were controlled by physical examinations, serological tests, US, and, in the case of equivocal US findings, by CT. The histological diagnoses of the operative specimen included hydatidosis in 43 patients, focal nodular hyperplasia (FNH) in 12 patients, liver cell adenoma in 8 patients, cavernous hemangioma in 8 patients, and congenital cyst in 4 patients. Hepatic scars were observed in 36 of the 75 patients. Four cases of intrahepatic recurrence and 1 case of intraperitoneal spread were observed in the 42 patients with recent hydatosis. Long-term postoperative controls (specific serological tests, US) are necessary in the management of patients with hydatid disease. Follow-up examinations are not indicated in asymptomatic patients who have been operated on for FNH, hemangioma, or congenital cysts.

The prevalence of lung cancer in vascular surgery patients

Inhalative cigarette smoking is a major risk factor for atherosclerotic disease as well as primary carcinoma of the lung. On that account, this study was performed to determine the prevalence of primary lung cancer on admission in patients scheduled for vascular surgery. All patients presenting to our department for an intervention are screened for lung diseases. If this pretherapeutic examination suggests the existence of a lung tumor further diagnostic procedures are performed. Making use of a prospective computer-assisted patient-documentation system, we analysed incidental findings of lung cancer in those patients admitted for elective surgery. Between Jan. 1st 1990 and October 31st 1994, we electively treated 2214 patients with the diagnosis of vascular stenosis (n = 1711/77.3%) or atherosclerotic aneurysms (n = 503/22.7%) in our department. In 16 of these patients (m:f = 13:3; age 50-72 [mean: 61.1] years) a carcinoma of the lung was detected during preoperative diagnostic procedures, a prevalence of 0.72%. All these patients were smokers, with a daily inhalative nicotine consumption averaging 25 cigarettes per day for a mean of 35 years. 8 patients underwent a surgical (n = 6) or other invasive (n = 2) vascular interventions. In 8 patients no vascular intervention was performed because of the revealed lung carcinoma. The prevalence of lung cancer in a population of vascular patients in the present study is in accord with data of older investigations of high-risk groups. Only 2 out of 16 lung cancers were detected at a prognostically favourable stage. Smokers with symptoms of vascular disease should be carefully examined for signs of lung cancer.

[Infections of the cervical spine]

Diagnosis of infectious disease of the spine in an early stage ist difficult. Conventional X-ray examinations, often used as a basic screening study, will show the characteristic narrowing of the intervertebral disc space and the osteolytic and sclerotic changes in the adjointing vertebra only after two to eight weeks. Magnetic resonance imaging (MRI) has a sensitivity equivalent to bone scintigraphy and, due to its superior delineation of anatomic details, MRI has become the method of choice not only for the assessment of location, extent, and associated lesions in infectious bone disease, but also in the diagnosis of intradural infections including myelitis. MRI examination in the assessment of a successful therapy or osteomyelitis of the spine aims for the detection of regression of bone marrow edema, reappearance of fatty marrow, and less pronounced contrast enhancement. Computed tomography (CT) is mainly used for image-guided biopsy to obtain specimen for microbiologic culture or for the placement of a percutaneous drainage.

Quantitative measurements with localized 1H MR spectroscopy in children with Canavan's disease

Canavan's disease is an autosomal recessive hereditary leukodystrophy resulting from deficiency of the enzyme aspartoacylase. Two children suffering from this metabolic brain disease were examined using image-guided localized proton spectroscopy. The absolute concentrations of metabolites were determined. These data demonstrate, for the first time, that the well known increase of the N-acetylaspartic acid (NAA)/Cho ratio in this disease may be not only due to a reduction of choline-containing compounds in brain tissue but, at least in specific cases, also due to an increase of the NAA concentration, which is a result of the enzyme defect.

Treatment of a ruptured anastomotic esophageal stricture following bougienage with a Dacron-covered nitinol stent

A patient suffering from esophagorespiratory fistula after bougienage of a benign stricture at the site of the anastomosis between a jejunal interposition and the esophagus was referred for interventional treatment. A prototype nitinol stent centrally covered with Dacron was implanted under regional anesthesia and fluoroscopic guidance. The self-expanding prosthesis dilated the stenosis completely and closed the fistula, with consequent improvement in respiratory and nutritional status and thus the general quality of life. The patient was able to eat and drink normally until death 3 months later due to progression of his underlying malignant disease.

[Local fibrinolytic therapy of arterial occlusions of the lower extremity: initial success and clinical outcome]

INDICATIONS

The efficiency of local fibrinolysis therapy in patients with chronic and acute peripheral arterial occlusions of the lower extremities has been investigated.

PATIENTS AND METHODS

A total of 33 patients were examined following a local fibrinolysis therapy (in 14 cases with supplementary percutaneous transluminal angioplasty) for chronic or acute peripheral arterial occlusion of the lower extremities. The success of the intervention was first evaluated by angiography and then by subsequent controls by means of treadmill ergometry.

RESULTS

A primary intervention success was achieved in 75.8% (25 of 33 patients) of the cases. In 18.2% (6 of 33 patients) a vascular surgical operation was required within 30 days of the intervention (5 therapy failures, 1 complication of the intervention). In two further patients, vascular surgery was necessary after five or six months. In 22 of the 25 successfully treated patients (92%), the Fontaine stage was reduced by at least one step after an average of 7.6 (range: 1 to 30) months.

CONCLUSIONS

Local lysis with or without PTA represents an effective alternative therapy to vascular surgery for the treatment of peripheral arterial occlusions in not immediately endangered lower extremities. On the basis of our results and a survey of the literature, an aid for selecting therapeutic measures for patients with arterial occlusion of the extremities is presented.

Angiographic detection of gastrointestinal bleeding. An experimental comparison of conventional screen-film angiography and digital subtraction angiography

RATIONALE AND OBJECTIVES

The authors experimentally assess and compare the detection limit of gastrointestinal bleeding in digital subtraction angiography (DSA) and conventional screen-film angiography.

MATERIALS AND METHODS

Arterial blood flow was simulated using a tube model in which bleeding was imitated by exudation of liquid containing contrast material. Gut peristalsis was imitated using silicone tubes filled with air and liquid. Images were acquired by DSA and conventional screen-film angiography. The iodine concentration was increased in increments from 1 mg I/mL, with and without simulated peristalsis, and with both free and circumscribed extravasation of contrast material.

RESULTS

The detection limit for free extravasation in DSA was 1 mg I/mL without peristalsis and 60 mg I/mL with peristalsis. The corresponding figures for circumscribed extravasation were 1 mg I/mL and 34 mg I/mL. The detection limit for free extravasation in screen-film angiography was 172 mg I/mL both with and without simulated peristalsis. Circumscribed extravasation was detected at 9 mg I/mL without peristalsis and 7 mg I/mL with peristalsis.

CONCLUSION

Digital subtraction angiography is the more sensitive angiographic technique for detection of gastrointestinal bleeding and is superior to conventional screen-film angiography, provided that it is performed with adequate parasym-pathicolysis and suspended respiration. Only when these requirements cannot be achieved is screen-film angiography advantageous.

[The radiological findings in surgically and conservatively treated intracranial arachnoid cysts]

PURPOSE

To determine which appearances on CT or MRI are indications for surgical treatment of intracranial arachnoid cysts.

METHOD

The images obtained from 26 patients treated either by surgery or conservatively were compared retrospectively. The features evaluated were the size of the cyst, evidence of a space-occupying lesion, cerebral abnormalities near the cyst and skull deformities.

RESULTS

In 6 patients (23%), surgical treatment was indicated because of the presence of obstructive hydrocephalus. The presence of all other radiological findings did not differ significantly between the two analysed groups. 92% of the patients treated surgically benefited from the treatment. Fenestration and shunting produced similar results in respect to reduction in size of the cyst and the clinical and neurological symptoms.

CONCLUSION

The only indication for surgery is the presence of obstructive hydrocephalus. The other features were seen equally amongst the patients treated conservatively and the surgical patients and had no influence on the decision to operate.

[The MR tomographic diagnosis of intra- and paraspinal abscesses]

PURPOSE

Analysis of the MRT signals and their extent from intra- and paraspinal abscesses with reference to predisposing factors, their causes and localisation.

PATIENTS AND METHODS

The histories and MRT findings in 34 Patients with intra- and paraspinal abscesses were evaluated retrospectively. Most of the patients (24/34) were older than 50 years. A second peak was below 30 years.

RESULTS

27/34 patients had some underlying disease which predisposed to infection, e.g., diabetes mellitus. The most common causal organisms were Staph. aureus (53%) and streptococci (15%). In 23/34 cases (68%), the abscesses were in the thoraco-lumbar or lumbar region, while only 6/34 occurred in the upper two-thirds of the thoracic spine and only 5/34 in the cervical region. In only 8/34 was the abscess confined to two vertebral lengths; in the remaining patients it was much more extensive. Intraspinal abscesses were about twice as large as the vertebral components and 1.5 times greater than paravertebral abscesses. The age of the abscesses could be estimated approximately from the signals.

CONCLUSIONS

Contrast enhanced MRT permits detailed analysis of the compartments and exact estimation of the extent of the lesions and permits accurate monitoring of treatment.

[A prospective study to assess the need for requested radiological studies]

PURPOSE

What is the percentage of non-indicated examinations in the routine work of a radiologic university clinic?

METHODS

From April 1st, 1994, to June 30th, 1994, all examinations carried out in the Radiology Department of the University Hospital of Cologne, Germany, were evaluated prospectively by the radiological medical staff using a questionnaire. The question was whether the examinations were medically indicated or not. Requests for examinations which were not carried out due to lacking indications were excluded from evaluation. The percentage of error was assessed by analysis of random samples assigned to the referring clinicians.

RESULTS

1400 (5.4%) of a total of 25718 examinations were considered by the radiological medical staff as "not indicated". A subsample analysis performed for validation gave an upper margin of a 95% confidence interval of about 13% for this rating. The percentage of non-indicated examinations was higher in conventional x-ray examinations and ultrasonography than in x-ray angiography, computed tomography and magnetic resonance tomography. Examinations during night time and weekend showed a higher percentage of lacking medical indications than examinations during daytime.

CONCLUSIONS

Considering a university clinic concerned with educational work, the percentage of radiological examinations carried out without medical indication was tolerable. However, indications must be further improved by intensifying the communication with the referring clinicians and by elaborating a higher standard of radiological and clinical postgraduate training.

Pharmacokinetics of intraarterial mitomycin C in the chemoembolisation treatment of liver metastases

1. The pharmacokinetics of mitomycin C (MMC) were investigated in 12 colorectal cancer patients with liver metastases undergoing chemoembolisation. Hepatic artery branches were embolized using polyvinylalcohol microspheres (150-250 microns) before applying 20 mg MMC in 4-8 min. 2. Serum MMC concentrations were determined from peripheral venous blood samples by reverse-phase HPLC using ultraviolet detection. Pharmacokinetic parameters were computed assuming an open two-compartment model. 3. Pharmacokinetic parameters were similar to values given in the literature for intravenous (IV) or intraarterial (IA) bolus MMC injections (Tmax = 7.0 min following the beginning of MMC infusion, Vss = 0.57 1/kg, C1 = 8.9 ml/min.kg, T1/2 alpha = 8.3 min, T1/2 beta = 58.6 min). 4. The area under the serum concentration-time-curve (AUC), standardized by the MMC amount injected, was similar to values reported in the literature for IV or IA bolus injections. There is no evidence for reduced systemic MMC exposure following the embolization procedure used.

Iodixanol vs iopamidol in intravenous DSA of the abdominal aorta and lower extremity arteries: a comparative phase-III trial

Iodixanol (Visipaque, 320 mgI/ml) was compared with iopamidol (Solutrast, 370 mgI/ml) in a double-blind, randomized, parallel group, intravenous DSA phase-III trial for evaluation of safety and efficacy. A total of 117 patients received iodixanol (n = 60) or iopamidol (n = 57). Diagnostic efficacy was evaluated using categoric and visual analogue scales. Discomfort and adverse events were recorded. A total of 39 patients collected urine up to 72 h after the examination for analysis. Diagnostic efficacy and radiographic density were similar in both groups. Discomfort was milder with iodixanol. The difference between the frequency of adverse events between both groups (iodixanol = 7, iopamidol = 2) was without statistical significance. Creatinine clearance was slightly more affected by iodixanol, whereas the increase in renal excretion of N-acetyl-beta-glucosaminidase (NAG) in the first 24-h collection period after the examination was significantly higher (p < 0.01) with iopamidol. Iodixanol was of equal diagnostic efficacy compared with iopamidol despite its reduced iodine content. Both contrast media are well suited for IV DSA.

Recurrent bleeding of angiomyolipomas in tuberous sclerosis

The diagnostic and therapeutic problems of renal hamartomas are illustrated by a case of recurrence of bleeding angiomyolipomas associated with tuberous sclerosis. Ultrasound and computed tomography provide clear evidence of lipomatous formation while, in rare instances, angiography can demonstrate the existence of multiple vascular tumor compartments. In view of the risk of bleeding, multiple or very large angiomyolipomas should be treated by interventional radiology in the form of superselective tumor embolization or by the most conservative surgery possible.

A gene for autosomal dominant paroxysmal choreoathetosis/spasticity (CSE) maps to the vicinity of a potassium channel gene cluster on chromosome 1p, probably within 2 cM between D1S443 and D1S197

Paroxysmal choreoathetosis/episodic ataxia is a heterogeneous neurological syndrome usually inherited in an autosomal dominant manner. Recently, the association of one form of episodic ataxia (defined by the presence of additional myokymia) with point mutations in the potassium channel gene KCNA1 was described. This gene locus on chromosome 12p (HGMW-approved symbol CSE) was excluded in a large pedigree with paroxysmal choreoathetosis and additional spasticity. Linkage to chromosome 1p where a cluster of related potassium channel genes is located, was demonstrated. Genotyping of 18 affected and 11 unaffected family members with 28 microsatellites over a region of 45 cM proved linkage with a lod score of 7.2 at a recombination fraction theta = 0 to D1S451/421/447/GGAT4C11. Crossing-over events in 9 patients and 4 unaffected offspring suggested a probable assignment of the gene to a region of 2 cM between D1S443 and D1S197.

[Spectroscopic imaging of the brain. Examination technique and clinical applications]

PURPOSE

MR spectroscopy allows the acquisition of a two-dimensional array of spatially resolved proton spectra of the human brain, known as MR spectroscopic imaging. Here the examination protocol and clinical applications in focal brain lesions are presented.

METHOD

An array of data is acquired from a tissue slice positioned in the brain. These data can be presented as a set of spectra, in which each spectrum is allocated to a specific position in the sample, or as a set of images or "metabolite maps".

RESULTS

The NAA signal typical for neuronal tissue is decreased in the centre of brain tumours as well as in brain infarcts. The intensity of the choline signal is increased in solid tumour tissue, whereas it is reduced in infarcts.

CONCLUSION

Spectroscopic imaging reveals metabolite alterations in and around focal lesions. The spatial resolution of spectroscopic imaging enables matching with other macro-morphological or functional imaging methods like positron emission tomography.

Intracerebral A lambda amyloidoma diagnosed by stereotactic biopsy

In a 70-year-old patient with an intracerebral tumor, the very rare diagnosis of an A lambda amyloidoma has been made by stereotactic biopsy using immunohistochemistry with a panel of antibodies directed against amyloid fibril proteins of various origins. The production by an apparent benign monoclonal plasma cell proliferation with secretion of paraproteins into the cerebrospinal fluid is assumed. It is the 4th case in which the amyloid protein was classified as derived from immunoglobulin lambda-light chains and, to our knowledge the first in which an A lambda amyloidoma has been diagnosed intra vitam. The amyloid is restricted to the brain and no systemic involvement has been detected. Therapeutic procedures are discussed.

Cine phase contrast angiography of normal and diseased peripheral arteries. Preliminary results

Cine phase contrast angiography (PCA) is a modified MR phase contrast sequence that acquires up to 22 coronal phase images per mean cardiac cycle. The ability of the sequence to visualise local haemodynamics was investigated in 7 normal volunteers and 9 patients with flow disturbances of the peripheral arteries using a 1.5 T imager. Functional flow information provided by coronal cine PCA was correlated with quantitative data obtained by MR flow measurements and vessel morphology confirmed by conventional angiograms. Due to the yet suboptimal image quality, an aortic dissection and 1 of 4 aneurysms could not be depicted morphologically. The temporal pattern of arterial perfusion in cine PCA corresponded with flow velocity versus time data provided by quantitative MR flow measurements. Accuracy and time resolution of cine PCA was thus sufficient to provide functional information on the severity of occlusive vascular disease.

MR pulsatility measurements in peripheral arteries: preliminary results

Phase contrast flow velocity measurements were performed in six healthy volunteers and 30 patients with arteriosclerotic disease. The iliac arteries were investigated in 8 cases and the femoral arteries in 28 cases. In the first 24 patients, 16 evenly distributed data sets were acquired during one cardiac cycle. In the last 12 patients, a trigger pulse followed by the acquisition of 30 evenly distributed data sets was applied every second heart beat. This procedure allowed data to be acquired over a full heart cycle without any acquisition gap. The measured flow velocities were displayed as function of time. Systolic acceleration, postsystolic deceleration and pulsatility of flow velocity were calculated and compared with stenosis grades determined from DSA angiograms. Flattening of the flow velocity patterns was found to correlate with the local severity of arteriosclerotic disease.

Magnetic resonance imaging and mood disorders. Localization of white matter and other subcortical abnormalities

BACKGROUND

Recent reports in the literature document an association between focal white matter abnormalities in bipolar as well as unipolar mood disorder. The importance of this finding and other associated anatomic differences is uncertain.

METHODS

We examined the volume of abnormal white matter and other brain volumes using quantitative magnetic resonance imaging analysis. We explored the relationship of these variables with diagnosis, cognitive function, and clinical variables in 36 patients with bipolar disorder, 30 patients with unipolar disorder, and 26 control subjects who were free from significant medical and neurologic illness.

RESULTS

Younger patients with bipolar disorder (but not similarly aged patients with unipolar disorder or controls) have an increased volume of abnormal white matter. Data also indicate that the total volume of abnormal white matter may be associated with increased cognitive impairment, increased rate of psychiatric illness in the family, and onset after adolescence.

CONCLUSION

Patients with bipolar disorder demonstrate a pattern of subcortical brain morphologic abnormalities and cognitive impairment.

Metabolic changes in acute and subacute cerebral infarctions: findings at proton MR spectroscopic imaging

PURPOSE

To analyze the advantages of proton magnetic resonance (MR) spectroscopic imaging in the evaluation of acute and subacute cerebral infarcts.

MATERIALS AND METHODS

Metabolite maps of choline-containing compounds, total creatine consisting of creatine and phosphocreatine, N-acetyl aspartate (NAA), and lactate were obtained in 23 patients with acute and subacute cerebral infarctions 1-35 days after onset of symptoms. Maps were obtained with a 1.5-T MR system with 32 x 32 phase-encoding steps.

RESULTS

Distinct abnormal metabolite distributions could be detected in all lesions larger than 1 cm in diameter. In the center of infarcts with a diameter larger than the section thickness of 2 cm, NAA values decreased to 20% +/- 8 compared with contralateral brain as early as 1 day after onset of symptoms (P < .0001). Choline was reduced to 67% +/- 30 (not significant) and creatine to 51% +/- 22 (P = .0025). Large amounts of lactate were detected in all acute infarcts. Choline, creatine, and lactate values declined during the first 5 weeks after stroke.

CONCLUSION

MR spectroscopic imaging allows visualization of metabolic changes in stroke with a reasonable spatial resolution.

Positron emission tomography and magnetic resonance spectroscopy of cerebral glycolysis in children with congenital lactic acidosis

Congenital lactic acidosis with neurological symptoms may be due to a variety of disorders of energy metabolism. We investigated whether positron emission tomography (PET) and proton magnetic resonance spectroscopy (1H MRS) are capable of demonstrating specific changes to facilitate diagnosis. A corresponding increase of cerebral lactate (with MRS) and rate of glycolysis (with PET) was observed in 2 children with biochemical evidence of defective mitochondrial respiration. No such increase was noted in a child with lactic acidosis due to stress and exercise but normal respiratory chain activity, and in a control case with an epilepsy syndrome without evidence of primary changes of energy metabolism. The results suggest that defects of oxidative phosphorylation may cause a massive increase of glycolysis to cover energy requirements, with corresponding accumulation of lactate in brain tissue. This mechanism can now be demonstrated in vivo and, with further experience, may potentially be used as a diagnostic marker of respiratory chain disorders in brain tissue.

Phase-contrast pulsatility measurements: preliminary results in normal and arteriosclerotic iliofemoral arteries. Work in progress

Magnetic resonance (MR) flow measurements were obtained in six healthy volunteers and 30 patients with arteriosclerotic disease with a 1.5-T imager and a pulse sequence for flow quantification based on flow-induced phase shifts. The iliac arteries were investigated in eight and the femoral arteries in 28 subjects. A trigger pulse, followed by the acquisition of 30 evenly distributed data sets, was applied every second heartbeat, thus eliminating any acquisition gap in a full heart cycle. For quantitative analysis, flow velocity was plotted as a function of time. Systolic acceleration, postsystolic deceleration, and pulsatility of flow were calculated and compared with stenosis grades determined from recent intraarterial digital subtraction angiograms. The flattening of the temporal flow patterns correlated with local severity of vascular occlusive disease.

[A comparison of NMR tomography and arthrography in functional disorders of the temporomandibular joint]

PATIENTS AND METHODS

31 patients with clinically diagnosed dysfunction of the temporomandibular joint (TMJ) were examined by magnetic resonance imaging (MRI; 1.5 Tesla, TR/TE 600/30) in closed and open mouth position and functional arthrography with digital image recording.

RESULTS

Both methods agreed in the evaluation of the disc position. In 23 joints with displaced disc reposition was found in 11 cases and in 14 cases using MRI or arthrography, respectively. MRI proved to be superior in the diagnosis of sideways disc rotations. Joint hypermobility, eccentric disc displacement (n = 4) and perforation (n = 3) were shown by functional arthrography. Due to the good demonstration of osseous, muscular and discoligamentous structures, MRI as a noninvasive imaging modality is the method of choice for TMJ evaluation. Arthrography can be advantageous in complex functional disturbances or if MRI and clinical findings are inconclusive. The clinical diagnosis of disc displacement was found to be accurate in only 68% of the cases.

[Peripheral occlusive arterial diseases: comparison of diagnostic value of MRA and DSA]

MATERIAL AND METHODS

In 59 patients with arterial flow disturbances 2-D inflow sequence of the abdominal and lower leg arteries were prospectively obtained on a 1.5 T MR-imager and were compared with additional DSA examinations. Supplementary Phase Contraste RSE ("Rapid Sequential Excitation") sequences were carried out in 29 patients. MRA and DSA angiograms were evaluated in random order by 4 readers using a questionnaire. The assessment of image quality were evaluated by variance analysis. Diagnostic performance of MRA and DSA was assessed by comparison of the readers' diagnostic assessments with reference diagnoses established by a radiologist and a vascular surgeon with full knowledge of all data concerning a patient. Image quality of inflow MRA was considered inferior to i.a. DSA (p < 0.001) and comparable with i.v. DSA (p = 0.1361). Image quality of RSE-MRA was inadequate (p < 0.001). Correspondingly, i.a. DSA was the superior and RSE-MRA the inferior imaging technique. The accuracy of inflow MRA in determining stenosis grade was 66% and that of RSE-MRA 59%.

Proton magnetic resonance spectroscopy reflects metabolic decompensation in maple syrup urine disease

Using localized proton magnetic resonance spectroscopy (1H-MRS), accumulation of branched-chain amino acids (BCAA) and their corresponding 2-oxo acids (BCOA) could be non-invasively demonstrated in the brain of a 9-year-old girl suffering from classical maple syrup urine disease. During acute metabolic decompensation, the compounds caused a signal at a chemical shift of 0.9 ppm which was assigned by in vitro experiments. The brain tissue concentration of the sum of BCAA and BCOA could be estimated as 0.9 mmol/l. Localized 1H-MRS of the brain appears to be suitable for examining patients suffering from maple syrup urine disease in different metabolic states.

Diagnostic performance of digital subtraction angiography (DSA) and magnetic resonance angiography (MRA): preliminary results in vascular occlusive disease of the abdominal and lower-extremity arteries

Fifty-nine patients with occlusive disease of the aorto-iliac and femoro-popliteal arteries were investigated prospectively by intravenous (IV) or intraarterial (IA) digital subtraction angiography (DSA) and magnetic resonance angiography (MRA). This was accomplished using a two-dimensional (2D) Inflow- (59 patients) and a 2D Phase Contrast- (RSE--rapid sequential excitation) sequence (29 patients). The spectrum of pathology included stenoses < 50%, stenoses 50-89%, stenoses 90-99%, occlusions, aneurysms and status following reconstructive surgery. MRA- and DSA-examinations were evaluated by four radiologists. The diagnoses were made by consent decisions of a radiologist and a vascular surgeon based on clinical and radiological findings. Diagnostic performance of IA-DSA was superior to all other imaging modalities. Vascular delineation of 2D Inflow-MRA was comparable to that of IV-DSA. The image quality of RSE-MRA was not adequate for diagnosis. In conclusion, 2D Inflow-MRA is a promising method for evaluating abdominal and peripheral arteriosclerotic disease. Interpretation of MR-angiograms, however, requires profound knowledge of MRA-techniques, X-ray angiography and hemodynamics.

[CT and MRT in progressive multifocal leukoencephalopathy (PML)]

Radiological findings and course of progressive multifocal leukoencephalopathy in 14 patients (1 woman, 13 men; 13 HIV seropositive, 1 chronic lymphatic leukaemia) were analysed retrospectively and correlated with clinical symptoms. A total of 21 CT and 16 MRI studies were evaluated. CT scans and MR images of 9 patients, which had been obtained in less than two weeks, could be compared to each other. MRI was superior to CT: 6 lesions with a diameter of 1 cm and below were not detected on CT scans, in 5 patients the extent of lesions was underestimated. Cortical involvement, mass effect or signs of atrophy were missing. Only 1 of 67 lesions showed a tiny enhancement after Gd injection. Due to the pattern and spread of lesions, which showed a close correlation to the neurologic symptoms, three different types of PML are suggested: 1. initial precentral demyelinisation with contralateral hemiparesis (n = 8); 2. lesions in temporo-occipital locations with visual disturbances (n = 2); 3. predominantly bilateral lesions of cerebellar white matter with ataxia (n = 4).

[Tuberculous meningoencephalitis with primary destruction of the cranial base and secondary development of multiple tuberculomas]

A 34-year-old Vietnamese patient presented with tuberculous meningoencephalitis complicated by hydrocephalus, diabetes insipidus, and radiological evidence of skull base erosion. Despite antituberculous treatment and corticosteroids multiple basal tuberculomas developed. Because of unusual CT and MRI findings casting some doubt on the diagnosis, brain biopsy was performed. The histological finding of an intracerebral tuberculoma supported the initial diagnosis. Some aspects of differential diagnosis and therapy are discussed, with reference to this case.

Lactate imaging of the human brain at 1.5 T using a double-quantum filter

The use of a double-quantum filtered 1H NMR spectroscopic imaging technique is described to detect the spatial distribution of lactate in the human brain. In two patients the feasibility of this technique is shown and compared with existing single-quantum spectroscopic imaging and single voxel techniques. Single-slice double-quantum filtered lactate images were obtained showing the lactate distribution over the entire slice in the brain. The lipid signal suppression was sufficient for the unambiguous detection of lactate. The signal loss of the lactate signal due to the incorporation of the double-quantum filter was 50-70% relative to the single-quantum signal.

Right proatlantal artery type I, right internal carotid occlusion, and left internal carotid stenosis: case report and review of the literature

A 66-year-old man presented with right cerebellar infarction and ischemic lesions in the left dorsal thalamus and right upper parietal lobe. Angiography showed occlusion of the right internal carotid artery proximal to an ipsilateral proatlantal artery type I, 70% stenosis of the left internal carotid artery, and aplasia of both posterior communicating arteries. The carotid occlusion was successfully treated by thrombendarterectomy. Persistence of a proatlantal artery is a rare condition. In relation to the 38 literature reports on proatlantal arteries, this case demonstrates the clinical significance of a persistent proatlantal artery in the evolution of atypical ischemic cerebrovascular disease.

Noninvasive detection of increased glycine content by proton MR spectroscopy in the brains of two infants with nonketotic hyperglycinemia

Using localized 1H-MR spectroscopy (1H-MRS) an inborn error of metabolism within human brain could be demonstrated, while 1H-MR imaging did not show any pathologic findings like demyelination. In two children suffering from nonketotic hyperglycinemia, the proton spectrum exhibited a large glycine signal at 3.55 ppm. In patient 1 (49-day-old girl), the pathologic signal of the inhibitory neurotransmitter glycine was of similar size in the parietooccipital white matter and in the basal ganglia region. In patient 2 (a 10-day-old girl), follow-up studies within the first 4 months of life revealed a time course of cerebral glycine content that differed from the course in plasma and cerebrospinal fluid. The continuing reduction of glycine in brain tissue corresponded more reliably with clinical findings than the stable values in plasma and cerebrospinal fluid. 1H-MRS allows the noninvasive demonstration of glycine in patients with nonketotic hyperglycinemia. This new technique may be useful to control the effect of a sodium benzoate therapy by monitoring the cerebral glycine concentration directly.

Human brain tumors: spectral patterns detected with localized H-1 MR spectroscopy

Image-guided localized proton magnetic resonance (MR) spectroscopy of intracranial tumors was performed to correlate spectral patterns and histologic findings. Thirty-six patients were examined prior to any specific treatment. Evaluation based on signal intensity ratios showed that all tumor spectra differed from spectra of healthy brain tissue. Ratios of creatine to choline-containing compounds (Cr/Cho) and nitrogen acetyl-aspartate to Cho (NAA/Cho) were reduced significantly in all tumor spectra compared with spectra of normal tissue in contralateral brain hemispheres (P less than .005). Noncerebral tumors typically showed a vanishing or missing NAA signal, strongly reduced Cr signal, and additional signals, assigned to alanine in meningiomas and lipids in metastases. In contrast, 11 gliomas of grades 2 and 3 exhibited NAA/Cho ratios and Cr/Cho ratios that were less than normal but that were significantly larger (P less than .01) than corresponding values in eight meningiomas. Ten glioblastomas displayed spectra with various signal ratios, so no significant differences between them and other tumor types could be established. In nine gliomas a clearly detectable lactate signal was present. However, no direct correlation between lactate level and histologic tumor grading was found.

In vivo imaging of glucose consumption and lactate concentration in human gliomas

Twenty patients with histologically confirmed gliomas were studied with positron emission tomography (PET) and proton magnetic resonance spectroscopy (1H-MRS). PET with 18F-2-fluoro-2-deoxy-D-glucose (FDG) provided tomograms of the metabolic rate of glucose. MRS images were obtained by combining volume-selective excitation with phase-encoded acquisition. With 32 x 32 gradient phase-encoding steps, an in-plane resolution of 7 x 7 mm was achieved. From this set of spectra, lactate maps were created and compared with PET maps of glucose metabolism. Maximum glucose metabolic rates within tumors (relative to metabolic rates of glucose in contralateral regions of the brain) were correlated significantly with maximum lactate concentrations (relative to N-acetyl aspartate peaks in the contralateral part of the brain). In 8 tumors, no lactate was detected, and in 7 of these the maximum glucose metabolic rate was below the median value. The tumor with the highest lactate concentration also had the highest glucose metabolic rate. The topographic relation between glucose metabolic rate and lactate concentration could be analyzed in 9 patients by three-dimensional alignment of the PET and MRS images. In that analysis, maximum lactate concentrations were often not found in the same location as maximum glucose metabolism, but lactate tended to accumulate in tumor cysts, necrotic areas, and the vicinity of the lateral ventricles. The combination of FDG PET and 1H-MRS imaging demonstrates details of the spatial relation between the two poles of nonoxidative glycolysis, glucose uptake and lactate deposition.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic imaging of patients with intracranial tumors: H-1 MR spectroscopic imaging and PET

Hydrogen-1 magnetic resonance (MR) spectroscopic images of patients with intracranial tumors were obtained. Metabolite maps of N-acetyl aspartate, choline, lactate, and creatine concentrations were reconstructed with a nominal spatial resolution of 7 mm and a section thickness of 25 mm. The metabolite maps showed variations in metabolite concentrations across the tumor. In one patient, it was observed that choline concentration was increased in one part of the tumor but decreased in another part. In another patient, the concentration of N-acetyl aspartate was extremely low in one part of the tumor but only slightly increased in another part of the tumor. Lactate was observed in all patients. In one patient, a combined measurement made with positron emission tomography (PET) and MR spectroscopic imaging was performed. This demonstrated that increased lactate concentration measured with H-1 MR spectroscopic imaging corresponded topographically with increased glucose uptake measured with fluorine-18 fluoro-2-deoxyglucose PET. Combined MR spectroscopic and PET measurements provide an opportunity to investigate, in greater detail than before, glucose uptake and catabolism by intracranial tumors.

[Intracranial hemorrhages in the magnetic resonance tomogram. Studies on sensitivity, on the development of hematomas and on the determination of the cause of the hemorrhage]

One hundred and forty-six intracranial hematomas in 129 patients were examined by MRI (136 examinations) and CT (147 examinations). Even using a high field MR system (1.5 T) and gradient-echo sequences, CT was the more sensitive method during the acute phase (46% compared with 93%). During the sub-acute phase, MR was superior to CT (97% compared with 58%), as it was in the chronic phase (93% compared with 17%). Petechial bleedings and discreet foci of contusion could only be demonstrated by MRI. Moreover, MRI showed evidence of residues from hemorrhage (signal reduction due to hemosiderin deposition) long after CT has become normal. Analyses of MRI images allows one to date the bleed and to distinguish between a) the formation of clot in a haemorrhagic cavity, b) bleeding into the tissues and c) a liquefying hematoma. Bearing in mind this classification, the localisation of the hematoma and the clinical findings mostly allow it is possible to determine the cause of the bleeding. Another advantage is the certain detection of vessels supplying arterio-venous malformations and cavernous hemangiomas.

Regional cerebral blood flow in patients with leuko-araiosis and atherosclerotic carotid artery disease

The relation between white-matter lesions (WMLs), demonstrated with magnetic resonance imaging, and regional cerebral blood flow (CBF), measured with dynamic positron emission tomography and [18F] fluoromethane, was investigated in 20 patients with atherosclerotic disease of the internal carotid artery. There was no correlation between the extent of small patchy WMLs and hemispheric CBF, but hemispheric CBF was significantly reduced in 5 patients with multiple large or confluent lesions. Distinct focal cortical CBF reductions were observed when large WMLs (greater than 5 mm) were located directly beneath the cortex, whereas large WMLs in deeper white matter were associated with a more diffuse decrease of cortical perfusion. There was no evidence of preferential CBF reduction in vascular border zones with increasing severity of WMLs or stenosis of the internal carotid artery. The side of previous transient ischemic symptoms correlated significantly with hemispheric CBF asymmetries, but not with asymmetries of WMLs and internal carotid artery stenosis. It can be concluded from these results that the presence of small patchy WMLs shown by magnetic resonance imaging cannot be used as evidence of impaired cerebral perfusion, while large lesions indicate clinically relevant cerebrovascular disease affecting cortical blood flow.