Effect of molecular weight on the diffusion of contrast media into cartilage

STUDY DESIGN: A comparison of contrast enhancement in the intervertebral disc from two magnetic resonance imaging contrast media in experimental animals. OBJECTIVES: To test the effect of molecular weight on the diffusion of ionic contrast media into the intervertebral disc. SUMMARY OF BACKGROUND DATA: Intravenously administered gadopentetate diffuses similarly into the fibrocartilage of intervertebral discs and herniated disc fragments. Differentiation between recurrent disc fragments and scar tissue via magnetic resonance imaging is optimized by using contrast media, which result in different contrast enhancement of these two tissues. Contrast media of higher molecular weight diffuse more slowly into cartilage; hypothetically, therefore, such media will produce better contrast between scar tissue and recurrent disc fragments. METHODS: Gadopentetate (molecular weight 546) or gadolinium-polylysine (molecular weight 40,000) was injected intravenously into rabbits. The signal intensities of intervertebral disc and muscle tissue were recorded by magnetic resonance imaging at baseline and at pre-determined intervals for 2 hours after injection of the contrast medium. Contrast enhancement in these tissues was calculated in each animal for each contrast medium, and differences in enhancement were tested for significance by a growth-curve model. RESULTS: Contrast enhancement in the intervertebral disc was significantly less with gadolinium-polylysine than with gadopentetate. In muscle, no significant difference between the two media was observed. CONCLUSIONS: Molecular weight affects the diffusion of paramagnetic contrast media into the intervertebral disc. Contrast media of a high molecular weight may produce better contrast between recurrent herniated disc fragments and scar tissue than contrast media of lower molecular weight. This possibility should be rested in further studies.     

The clinical significance of gadolinium enhancement of lumbar disc herniations and nerve roots on preoperative MRI

The clinical significance of preoperative gadolinium DPTA enhancement around disc herniations and in the epidural space on MRI is not clear. The relation of nerve root enhancement to dysfunction also remains controversial. To investigate the clinical significance of contrast enhancement we looked at the symptoms and signs and gadolinium DPTA-enhanced images of 71 consecutive surgical candidates in a standardised fashion. Annular rupture and disc enhancement were found to be closely related, and correlated with sensory loss and paresis, respectively. Nerve root enhancement was found to be related to neurological deficits in general and sensory impairment in particular.     

Computer-based diagnosis support for the interpretation of Hess charts

RATIONALE AND OBJECTIVES: The use of gadolinium (Gd)-BOPTA as a magnetic resonance contrast agent for central nervous system disease was studied in a canine brain abscess model. METHODS: A Streptococcus faecalis brain abscess was evaluated in five dogs at 1.5T. Imaging was performed during the late cerebritis stage, at 5 to 7 days after surgery. Magnetic resonance scans were acquired before and at 1, 5, 15, 30, 45, and 60 minutes after contrast administration, using a dose of 0.1 mmol/kg. Scans also were acquired both before and after contrast injection with the implementation of magnetization transfer. RESULTS: Lesion enhancement, quantified by region-of-interest measurement, peaked at 5 minutes after contrast injection. Both the increase in lesion enhancement from 1 to 5 minutes after injection and the decrease from 5 to 15 minutes after injection, although small, were statistically significant (P < 0.004 and P < 0.03, respectively). The application of magnetization transfer improved lesion enhancement, as measured by signal difference/noise, by 39%. This result also was statistically significant (P < 0.001). CONCLUSIONS: In intraparenchymal brain infection, Gd-BOPTA provides effective lesion enhancement when used at a dose of 0.1 mmol/kg. Further research is needed to compare the magnitude of enhancement achieved with Gd-BOPTA, which has weak protein binding and both hepatobiliary and renal excretion, with that with Gd chelates, which have pure renal excretion.     

Contrast magnetic resonance imaging in the assessment of myocardial viability in patients with stable coronary artery disease and left ventricular dysfunction

BACKGROUND: The utility of contrast MRI for assessing myocardial viability in stable coronary artery disease (CAD) with left ventricular dysfunction is uncertain. We therefore performed cine and contrast MRI in 24 stable patients with CAD and regional contractile abnormalities and compared MRI findings with rest-redistribution 201Tl imaging and dobutamine echocardiography. METHODS AND RESULTS: Delayed MRI contrast enhancement patterns were examined from 3 to 15 minutes after injection of 0.1 mmol/kg IV gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA). Comparable MRI and 201Tl basal and midventricular short-axis images were subdivided into 6 segments. Segments judged nonviable by quantitative and qualitative assessment of 201Tl scans showed persistent, systematically greater MRI contrast signal intensity than segments judged viable (P相似文献   

Current uses of gadolinium chelates for clinical magnetic resonance imaging examination of the liver

The use of gadolinium chelates has become an integral part of magnetic resonance imaging (MRI) of the liver and extrahepatic abdomen. Although liver specific contrast agents are now available, gadolinium chelates continue to offer significant advantages for abdominal MRI. The gadolinium chelates uniquely provide important information about tumor perfusion that is key in our assessment of liver masses. These paramagnetic contrast agents assist with liver lesion detection, characterization, and in establishing the volume of viable perfused tumor. Gadolinium chelates are equally important for MRI of the extrahepatic abdomen. The interstitial accumulation of these agents within peritoneal, omental, and gastrointestinal tumor produces marked enhancement and is key in accurate tumor staging. Depiction of lesions within solid visceral organs such as the pancreas, kidneys, and spleen is also improved following gadolinium injection. The versatility of this workhorse contrast agent assures that gadolinium chelates will continue to occupy a central role in any busy abdominal MRI practice.     

The advantage of magnetic resonance imaging in diagnosis of cauda equina syndrome in dogs

Three dogs were evaluated in our study using magnetic resonance imaging (MRI) to reveal the anatomical deformity and the degree of the lesion of cauda equina. In all dogs, MRI revealed soft tissue, such as cauda equina, epidural fat, and intervertebral disc, at the lumbosacral region clearly without contrast medium. Our results suggest that MRI has some advantages in evaluating cauda equina syndrome in dogs.     

Tumor imaging with a macromolecular paramagnetic contrast agent: gadopentetate dimeglumine-polylysine

RATIONALE AND OBJECTIVES: We evaluated magnetic resonance (MR) contrast enhancement of tumor tissue following injection of the macromolecular conjugate, gadopentetate dimeglumine-polylysine. METHODS: T1-weighted MR imaging scans were performed on female Fisher-344 rats with subcutaneously implanted mammary adenocarcinoma tumors. Following the baseline scan, gadopentetate dimeglumine-polylysine or gadopentetate dimeglumine was injected at a dose of 0.1 mmol gadolinium per kilogram. RESULTS: Gadopentetate dimeglumine-polylysine injection resulted in a maximum enhancement of tumor contrast of 310 +/- 60% (n = 7). Tumor tissue remained enhanced and well defined for several days after gadopentetate dimeglumine-polylysine injection. Gadopentetate dimeglumine injection at the same dose resulted in a 70 +/- 25% (n = 4) maximal tumor enhancement and a corresponding 25 +/- 4% muscle enhancement. CONCLUSION: Gadopentetate dimeglumine-polylysine provides higher, more sustained tumor contrast than does gadopentetate dimeglumine for the same dosage of gadolinium.     

MR imaging in pretruncal nonaneurysmal subarachnoid hemorrhage: is it worthwhile?

BACKGROUND and PURPOSE: The cause of pretruncal (perimesencephalic) nonaneurysmal subarachnoid hemorrhage is not known. MRI of the brain or spine is often performed to exclude any other vascular abnormalities. Its diagnostic value is not known. METHODS: We used MR imaging of the brain with routine sequences, gadolinium enhancement, and additional thin T1-weighted axial sections following a triple dose of contrast. RESULTS: We performed MR imaging of the brain in 18 patients with a pretruncal nonaneurysmal subarachnoid hemorrhage. The focal nature of the subarachnoid hemorrhage exclusively in front of the brain stem was confirmed in 14 patients studied within 7 days of the ictus. No vascular abnormalities were found in 17 cases, including 14 patients with gadolinium enhancement. An incidental capillary telangiectasia was found in 1 patient. Fluid-attenuated inverse recovery MR additionally documented blood in the sulci due to cerebrospinal fluid recirculation of blood. Five patients underwent MR imaging of the spine, and no arteriovenous malformations were found. CONCLUSIONS: MR imaging did not reveal a source of pretruncal subarachnoid hemorrhage. The cost of MR imaging probably outweighs the benefit in the evaluation of this variant of subarachnoid hemorrhage.     

Indication and clinical results of laminoplasty for cervical myelopathy caused by disc herniation with developmental canal stenosis

STUDY DESIGN: The outcome of a herniated disc in patients with cervical myelopathy treated by laminoplasty without discectomy and in those treated conservatively was studied by magnetic resonance imaging. OBJECTIVES: To compare the surgical results of laminoplasty with those of anterior spinal fusion in patients with myelopathy caused by to cervical disc herniation and to make a treatment strategy for cervical disc herniation depending on these results. SUMMARY OF BACKGROUND DATA: Anterior discectomy and spinal fusion have had acceptable surgical results, but many complications have been reported, especially adjacent segment degeneration and bone graft complications. METHODS: Forty-seven patients with cervical disc herniation were examined in this study. Of them, 32 patients (mean age, 56 years) underwent laminoplasty without resection of the herniated disc. Seven patients with mild cervical myelopathy and 8 patients with radiculopathy (mean age, 53 years) were treated conservatively. As a control group, 44 patients (mean age, 50.3 years) who underwent anterior spinal fusion were examined. All patients in the laminoplasty group also had congenital spinal canal stenosis in which the ventrodorsal canal diameter was less than 13 mm. The association between the outcome of a herniated disc and clinical features was investigated. The severity of myelopathy was evaluated according to the Japanese Orthopaedic Association's scoring system. Surgical outcomes were evaluated by the system of Hirabayashi for determining recovery rate. RESULTS: The recovery rate averaged 67.9% in laminoplasty and 68.8% in anterior spinal fusion. There were no significant differences between the groups. No patients underwent anterior spinal fusion after laminoplasty. Follow-up magnetic resonance imaging showed regression of the size of the herniated disc in 15 of the 20 patients in the laminoplasty group and in 12 of 15 patients treated conservatively. In the MRI studies of the natural course of disc herniation, the size of the herniated disc decreased to almost half in 1 to 2 months and almost disappeared within 3 months after surgery. CONCLUSIONS: The size of the herniated disc in cervical lesions regressed as it does in the lumbar lesions. Laminoplasty for patients with narrowed spinal canals showed favorable surgical results. Therefore, the therapeutic method for cervical disc herniation should be chosen after taking the natural history of the disc herniation into consideration.     

Herniated intervertebral disc without pain

The diagnosis of herniated intervertebral disc is often made in cases of radicular pain in the low back, the neck, or sciatica or brachialgia. Practitioners often call upon radiologic imaging to confirm this diagnosis. But on radiologic examination, such a herniation may consist of a bulge, protrusion, prolapse, extension, extrusion or sequestration of this disc. We define and illustrate these terms from the literature. We then review the radiologic studies of normal controls, who have never had sciatica, brachialgia or pain in the low back or neck. In over one-quarter of these controls, studies using the plain x-ray, CT scan, myelogram, and MRI show various radiologic signs of a herniated intervertebral disc. We therefore recommend that practitioners should not exclusively rely on radiologic imaging to confirm the clinical diagnosis of a herniated intervertebral disc.     

A comparison of two MR hepatobiliary gadolinium chelates: Gd-BOPTA and Gd-EOB-DTPA

PURPOSE: Two gadolinium chelates with partial hepatobiliary excretion, Gd-BOPTA and Gd-EOB-DTPA, and one gadolinium chelate with exclusively renal excretion, Gd-HP-DO3A, were compared on MRI at 1.5 T. The time course of enhancement for normal liver, gallbladder, spleen, kidney, and muscle was specifically examined in the rhesus monkey. METHOD: Four animals were evaluated with each agent for a total of 12 MR studies. Breath-hold and non-breath-hold T1 weighted scans were acquired prior to and 1, 2, 3, 4, 5, 15, 30, 45, 60, 75, and 90 min after intravenous contrast medium injection. The same contrast dose, 0.1 mmol/kg, was used for all studies. Images were analyzed by region-of interest measurements. RESULTS: Both hepatobiliary gadolinium chelates achieved sustained enhancement of normal liver parenchyma, superior in magnitude to that following Gd-HP-DO3A injection. On sans 45-90 min following injection, liver enhancement with Gd-BOPTA was superior to that with Gd-EOB-DTPA. This difference was, however, not statistically significant. Liver enhancement decreased more rapidly on delayed scans with Gd-EOB-DTPA than with Gd-Bopta, a result that was statistically significant. Excretion of contrast agent into the gallbladder was noted with both hepatobiliary agents but not with Gd-HP-DO3A. CONCLUSION: Enhancement of normal liver parenchyma peaks at a later time after injection with Gd-BOPTA than with Gd-EOB-DTPA. However, the maximum percent enhancement is comparable when (as in the current evaluation) the two agents are compared at the same dose (0.1 mmol/kg). This finding supports the choice of optimal imaging time post contrast agent administration (for delayed scans) in clinical trials of 20-45 min post injection with Gd-EOB-DTPA and 60-120 min post injection with Gd-BOPTA.     

Reoperation for recurrent coronary artery disease: results of 200 consecutive cases

OBJECTIVE: To quantify first-pass enhancement of cervix carcinoma using fast dynamic MRI. To assess the accuracy of dynamic contrast-enhanced colour-coded MRI for determining tumour invasion into surrounding pelvic tissues. METHODS: Gadolinium enhanced dynamic MRI at one image every 2 s was performed in 47 patients with cervical carcinoma and five controls. First-pass contrast enhancement of cervix carcinoma and surrounding pelvic tissues was quantified. Automated colour-coded images were constructed using the dynamic parameters slope, amplitude and timing of enhancement. Of 47 patients, 28 underwent surgery and colour coded images were correlated with histological findings. RESULTS: First-pass contrast enhancement imaging of cervix carcinoma required a temporal resolution of dynamic MRI of one image every 3-4 s. Cervix carcinoma first-pass was more rapid and intense than that of other pelvic tissues (P<0.001) with the exception of normal myometrium (P>0.05). Binary colour coding, however, was not reliable for tumour delineation or for accurate assessment of tumour invasion into the parametria or the bladder wall. Overestimation of the extent of tumour invasion occurred in 15, 16 and nine out of 28 patients, respectively, using amplitude, slope and timing of enhancement as parameters. CONCLUSION: Dynamic contrast-enhanced colour-coded MRI of cervix carcinoma has limited value for assessing the extent of tumour spread and tumour staging.     

Effects of oral treatment with sustained release morphine tablets on hypothalamic-pituitary-adrenal axis

A 31-year-old black male with sarcoidosis en-plaque of the dura mater, which is a rare morphological variant of neurosarcoidosis (NS), presented at our clinic. Magnetic resonance imaging (MRI) of the head with gadolinium showed non-specific enhancement of both tentorial leaves extending to the floor of right middle cranial fossa and cavernous sinus. The laboratory results were normal except for slightly increased serum angiotensin converting enzyme (SACE) (68 U/ml n = 4-56 U/ml) and cerebrospinal fluid (CSF) IgG index (0.57, n = 0.46). Biopsy of the intracranial dural lesion was consistent with sarcoidosis. Oral steroid therapy (Methylprednisolone 4 mg QID) was started and the patient became asymptomatic. However, MRI of the brain with gadolinium 2 months after biopsy showed progression and extension of the enhanced dural lesion. His SACE level was unchanged. We concluded that progression of the enhanced lesion seen in MRI could be recently formed scar tissue, new lesion or both. MRI findings should always be correlated with clinical findings for evaluation of NS during follow-up.     

Soft tissue for allograft reconstruction of the human knee: a survey of the American Association of Tissue Banks

STUDY DESIGN: The reactions to sequestrated disc fragments, which were removed surgically from 35 patients, were examined histologically. OBJECTIVES: To elucidate whether or not there is histologic evidence of absorption of sequestrated discs. SUMMARY OF BACKGROUND DATA: Spontaneous disappearance or diminution of lumbar herniated discs in the spinal canal has been recognized, and this could be a possible explanation for relief of symptoms without surgery. The mechanism of this phenomenon is unclear. METHODS: Sequestrated discs removed surgically from 35 patients were examined histologically. RESULTS: In 30 cases, neovascularization was observed at the periphery of the sequestrated discs. Many foamy cells (macrophages) were present in the vascularized areas. In addition, immunohistochemistry revealed that many spindle-shaped, fibroblast-like cells were positive for CD68, a marker of macrophages. No fibrous scar formation was observed in any region. CONCLUSION: These findings suggest that organization is not a main course for this type of herniated disc and that a kind of "absorption" process occurs predominantly in the healing stage.     

Gadolinium and contrast medium MRI of the acoustic nerve in patients with meningeal neuritis and acoustico-facial syndrome

Twelve cases of vestibular neuritis were investigated in gradient echo MRI with gadolinium. Only 3 severe cases associated with an acoustico facial syndrome (2 cases of herpes zoster oticus and one case after influenzae) demonstrated focal enhancement within the internal auditory canal on post contrast T1 weighted images. This enhancement involved at least 2 differents nerves. These 3 severe cases associating sensory neural hearing loss and facial palsy revealed a meningeal reaction after cerebrospinal fluid examination. The enhancement lasted a long time (up to 10 months) in one case of RAMSAY HUNT syndrome associated with a chronic lymphocytic leukemia. The MRI was able to confirm the anatomical reality of the vestibular neuritis and more precisely of the meningoneuritis and gave arguments for the theory of the polyneuropathy of Adour. Enhancement at MRI seems correlated with the severity of the affection (permanent vestibular areflexia in 3 cases and permanent hearing loss in 1 case).     

Fragment excision versus conventional disc removal in the microsurgical treatment of herniated lumbar disc

100 patients who had a lumbar microdiscectomy were retrospectively compared with 100 microsurgically treated patients who had only a removal of the herniated disc fragment. We were able to show that there are less "reherniations" in the fragment removal group and the clinical outcome is often better regarding postoperative problems of instability.     

Detection of hepatic tumors: arterial-phase MR imaging versus spiral CT arteriography

BACKGROUND: Distinction between uncomplicated infective fasciitis and early necrotizing fasciitis can be extremely difficult without operation, yet the management and prognosis of both conditions depend greatly on early recognition and assessment of the extent of involvement. STUDY DESIGN: This was a prospective review of the utility of magnetic resonance imaging (MRI) in nine patients with suspected infective or necrotizing fasciitis treated at an academic medical center or a Veterans Administration hospital. RESULTS: Magnetic resonance imaging documented fascial inflammation, characterized by low intensity on T1-weighted images and high intensity on T2-weighted images, in all nine patients. Absence of gadolinium contrast enhancement on T1-weighted images reliably detected fascial necrosis in all six patients who required operative debridement. Magnetic resonance imaging was extremely useful in defining the extent of fasciitis and was more accurate in predicting necrosis or pyomyositis than was myoglobinuria or elevation of serum creatine kinase or lactate dehydrogenase. Operation was avoided in two patients without evidence of necrosis on MRI. One patient without evidence of necrosis, explored because of contradictory clinical findings, was confirmed at operation to have cellulitis without necrosis. CONCLUSIONS: Magnetic resonance imaging with gadolinium contrast accurately determines the presence of necrosis and the need for operation in patients with fasciitis of the lower extremity. Preoperative determination of the extent of involvement facilitates operative planning.     

Attenuation characteristics and application of gadolinium-DTPA in fast helical computed tomography

RATIONALE AND OBJECTIVES: The computed tomography (CT) attenuation characteristics of gadolinium (Gd)-DTPA have been analyzed both in vitro and in vivo to evaluate the possibility of its substitution for iodine in patients with contraindications for iodine utilization. METHODS: In vitro attenuation values of Gd-DTPA were measured relative to those of iodine under variation of concentration, voltage, preattenuation, and beam hardening. In vivo iodine attenuation values were obtained for different injection rates (3.0 mL/second and 4.5 mL/second) to calculate the attenuation values of 0.5 molar Gd-DTPA to be expected in vivo by the help of the previously obtained attenuation-concentration curves. Subsequently, CT enhancement after an injection of 0.3 mmol/kg body weight Gd-DTPA was evaluated in five patients with contraindications for iodine administration. RESULTS: The injection of a 0.7 molar Gd-DTPA solution at a flow rate of 4.5 mL/second was calculated to be equivalent to that of 2.36 molar iodine at a flow rate of 3 mL/ second. Sufficient enhancement for diagnosis of dissections/ aneurysms of arterial vessels could be achieved. Both arterial and venous cervical or thoracic vessels could be enhanced to 100 Hounsfield units with a bolus injection. In contrast to the thyroid gland, the parenchyma of the liver and the kidney was not sufficiently enhanced. CONCLUSIONS: Gadolinium-DTPA is more effective than iodine in x-ray attenuation; however, its present concentration of 0.5 molar and permitted dose of 0.3 mmol/kg body weight are insufficient to provide parenchymal enhancement with CT. The visualization of arterial vessels appears possible with gadolinium enhanced CT but requires optimal timing and fast scanning capabilities.     

Focal malignant hepatic lesions: MR imaging enhanced with gadolinium benzyloxypropionictetra-acetate (BOPTA)--preliminary results of phase II clinical application

PURPOSE: To investigate enhancement with gadolinium benzyloxypropionictetraacetate (BOPTA) at magnetic resonance (MR) imaging to detect focal malignant hepatic lesions. MATERIALS AND METHODS: A phase II trial was performed in 34 patients. Gd-BOPTA-enhanced spin-echo (SE) and gradient-recalled-echo (GRE) T1-weighted MR imaging were performed at 40 and 90 minutes after intravenous injection of 0.05 and 0.10 mmol/kg Gd-BOPTA. RESULTS: The percentage of enhancement in liver parenchyma was significantly (P<.05) increased on GRE T1-weighted compared with SE T1-weighted images at 40 and 90 minutes after injection of the higher dose and compared with SE and GRE T1-weighted images obtained with the lower dose. The contrast-to-noise ratio of metastases was significantly increased on GRE T1-weighted images (0.10 mmol/kg) at 90 minutes compared with precontrast images. Significantly more small primary metastases were detected on GRE T1-weighted images (0.10 mmol/kg) at 90 minutes compared with precontrast SE T1-weighted images. CONCLUSION: Gd-BOPTA is a safe hepatobiliary contrast agent that helps detection of small metastases.     

Influence of fibrinolytic factors on scar formation after lumbar discectomy. A magnetic resonance imaging follow-up study with clinical correlation performed 7 years after surgery

STUDY DESIGN: Prospective cohort study. OBJECTIVES: To assess the amount of scar tissue by viewing magnetic resonance images, and to evaluate the correlation between the amount of scar tissue and clinical outcome, surgical technique, and fibrinolytic factors. SUMMARY OF BACKGROUND DATA: The influence of fibrinolytic factors on magnetic resonance images has not been investigated previously. The relation between clinical outcome and findings on magnetic resonance imaging remains uncertain. METHODS: Magnetic resonance imaging at 0.5 Tesla was performed to produce sagittal and axial spin-echo T1-weighted images before and after contrast enhancement on 78 patients 7 years after traditional lumbar discectomy with partial or full laminectomy. Before surgery all patients had been tested for fibrinolytic factors. RESULTS: The overall clinical success rate of the surgery was 73%. No evidence of scar formation was seen in 19 patients, a small amount was seen in 36 patients, a moderate amount in 17 patients, and a large amount was observed in 6 patients. Ten patients who had undergone surgery at two disc levels and 18 who had been treated with full laminectomy exhibited more scar tissue than those patients who had undergone surgery on a single level (P = 0.033) and those who had undergone a partial laminectomy, respectively (P = 0.017). The amount of scar formation also was associated with a poor outcome (P = 0.017) and with low preoperative values of tissue plasminogen activator antigen (P = 0.003) and tissue plasminogen activity (P = 0.048) in samples collected after venous occlusion. The intensity of contrast enhancement, however, was not influenced by these or any other parameters. CONCLUSION: The amount of scar formation after lumbar discectomy seems to be related to the clinical outcome, the size of the surgical exposure, and some fibrinolytic factors.