Appearance of Pantopaque on MR images

Pantopaque was shown to be both a radiographic and magnetic resonance (MR) contrast agent in two patients with suspected cord abnormalities who underwent MR examination following myelography. The Pantopaque appeared as a linear band of high signal intensity along the dependent portion of the spinal canal on MR images obtained with a repetition time of 500 msec and an echo time of 30 msec. MR images of two dogs--one injected with Pantopaque in the cervical subarachnoid space and the other with Amipaque--confirmed that the high signal arose from the Pantopaque. This high signal intensity is due to Pantopaque's short T1 relaxation time. Although Pantopaque will probably not be used as an MR contrast agent, it is important to recognize this property so that its high signal is not mistaken for fat or hemorrhage in the subarachnoid space on MR images.     

Experimental production of arachnoiditis with glove powder contamination during myelography

Adhesive spinal arachnoiditis is a rare condition of several causes, including complications of myelography. An experiment was conducted to study the effects of surgical glove powder contamination in the cerebrospinal fluid. The subarachnoid space of 45 rabbits was injected with either a suspension of powder from sterile surgical gloves, Pantopaque (iophendylate), or a combination of the two agents. Mild to severe arachnoiditis was produced in 10 of 17 animals injected with the combination of powder and Pantopaque. Only two of 16 rabbits injected with glove powder and one of nine with Pantopaque had more than minimal changes of arachnoiditis. Three rabbits (two injected with glove powder alone and one with both agents) died of meningitis within 1 week of injection. The combination of glove powder and Pantopaque is synergistic in producing arachnoiditis. These results emphasize the importance of meticulous technique in myelography.     

Obstructive hydrocephalus following Pantopaque myelography

Summary A case with delayed development of obstructive hydrocephalus most probably caused by Pantopaque myelography is reported. At autopsy it was found that the foramina of Magendi and Luschka were occluded by granulation tissue in which the most common findings were multinucleated giant cells containing calcareous and unstained vacuoles, frequently surrounding empty hollows, many lymphocytes and plasma cells. As compared with two other similar cases and several animal investigations this shows that the reaction of the tissue is typical of a Pantopaque reaction.     

The behavior of Pantopaque on MR: in vivo and in vitro analysis

MR imaging is considered by many to be the procedure of choice in imaging the spinal cord; yet we encountered an important pitfall of this procedure in the form of a patient with retained intraspinal Pantopaque. The results of this case are presented as well as those obtained in another patient with retained Pantopaque. Also described is the behavior of this contrast material when using in vitro imaging data obtained from a CSF/Pantopaque phantom. When T1-weighted imaging sequences are used, Pantopaque gives a high signal and CSF gives a low signal. With long repetition time, (e.g., 4000 ms), the CSF signal is high and the Pantopaque signal is not. With repetition time around 1000 to 2000, both may be isointense. The implications of these findings are discussed.     

Pantopaque pulmonary embolism following myelography

Summary A patient with radiological evidence of Pantopaque embolism in the lungs following myelography is reported.     

Arachnoid response to contrast media: a comparison of iophendylate and metrizamide in experimental animals

Arachnoiditis resulting from administration of intrathecal iophendylate (Pantopaque) was compared with that from metrizamide (Amipaque) in 16 monkeys. Four animals initially underwent metrizamide myelography, eight underwent iophendylate myelography, and four control animals received only cerebrospinal fluid. Twelve weeks later, all 16 animals underwent metrizamide myelography and then histologic studies. Animals receiving iophendylate for the first myelogram differed significantly from the other two groups on inflammation, fibrosis, and myelographic evidence of arachnoiditis. The arachnoiditis produced by iophendylate was more severe than that produced by metrizamide; the iophendylate also produced a more cellular reaction that was qualitatively different from the reaction to metrizamide. This more severe reaction to iophendylate has clinical implications for patients undergoing myelography if the contrast medium is not completely removed from the system after myelography.     

Myelographic evaluation of nontraumatic spinal canal obstruction: a new approach.

A new technique simplifies the evaluation of the spinal canal above obstructing lesions encountered during myelography via the lumbar route. After the demonstration of a block with 2--4 ml Pantopaque, a second injection of 2--4 ml Pantopaque is made through the lumbar needle with the patient in 45 degree Trendelenberg (or any degree necessary to keep the initial contast bolus against the inferior margin of the obstruction). In all 10 cases in this series, the second injection easily displaced contrast around and above obstructions that could not be overcome by gravity thereby obviating a lateral cervical or cisternal puncture. No technical failures of complications were encountered. The method is not recommended in cases of traumatic spinal canal obstruction.     

In vitro proton T1 and T2 studies on rat liver: analysis of multiexponential relaxation processes

At 37 degrees C and 20 MHz, the T1 and T2 proton relaxation processes in intact rat liver tissue are multiexponential functions which in the majority of cases were decomposed into a major (alpha* approximately 90%, T1* = 374 ms, T2* = 58 ms) and a minor (alpha** approximately 10%, T1** = 130 ms, T2* = 181 ms) component. Both, T1 and T2, are temperature-dependent with a temperature shift of delta T1 = 1.5 ms/degrees C and delta T2 = 0.5 ms/degrees C, respectively. Storage of liver tissue at 4 degrees C and 37 degrees C led to remarkable changes of the T1 and T2 values. For T2 these changes occurred after a shorter storage time than for T1, but they are more pronounced for T1. To avoid such influences the relaxation measurements were performed within one hour after excision of the tissue. Even at 4 degrees C, long-term storage (greater than 3 h) must be avoided. A method for the quantitative determination of the fat content in liver based on multiexponential analysis of the T1 relaxation process was evaluated employing mixtures of triolein with liver homogenate. Triolein is a two-component system with T1* = 144 ms (alpha* = 62%) and T1** = 355 ms (alpha** = 38%). Finally, liver-specific protocol conditions were defined for in vitro relaxation studies.     

Magnetic resonance myelography evaluation of the lumbar spine end plates and intervertebral disks

PURPOSE: To evaluate the value of magnetic resonance (MR) myelography in the evaluation of intervertebral disk and end-plate degenerative changes in the lumbar spine. MATERIAL AND METHODS: Conventional MR and MR myelography examinations were performed in 150 consecutive patients (69 F and 81 M, mean age 45+/-15 years, range 18 89). Sagittal T1 and T2-weighted TSE images were compared to MR myelography obtained with a multishot-TSE-T2-weighted sequence (4000/250/fat suppression). Coronal, sagittal, and both oblique MR myelography projections were obtained. Image analysis was carried out independently by two radiologists who categorized lumbar disks into normal, degenerated, or edematous; and vertebral end plates into normal, edematous, or with fatty changes. The proportions were statistically compared at every lumbar intervertebral level. RESULTS: There was good agreement in the classification of disk disease (Kappa: 0.8-0.9). MRI detected a larger number of disk degeneration and end-plate fatty metamorphosis, while the MR myelography technique depicted a larger number of edematous disks and end plates. CONCLUSION: MR myelography was of limited value in detecting the same vertebral end-plate changes observed in MRI, although with similar findings in disk disease. However, the higher detection of edema changes by MR myelography should be analyzed prospectively, as it could be more sensitive than conventional MR sequences.     

MR relaxation times of cerebrospinal fluid

A review of 15 recent publications purporting to provide the relaxation times of CSF reveals a considerable disparity in the quoted results, by a factor of five in terms of T1 (range 1,000 to 5,500 ms) and by a factor of 16 for T2 (range 166 to 2,640 ms). In this article measurements are performed independently on both a spectrometer and an imager. The results indicate that for CSF T1 is greater than 3,000 ms and T2 is approximately 2,000 ms at 6 MHz. The vast differences in relaxation behaviour between CSF and other body tissues have considerable clinical implications and present profound diagnostic opportunities. The application of this knowledge to ventriculography, myelography, and image contrast methodology is discussed.     

MR椎管造影的影像学表现

目的：报道椎管常见病变的ＭＲ椎管造影表现。材料与方法：ＭＲ为Ｓｉｅｍｅｎｓ Ｍａｇｎｅｔｏｎ Ｉｍｐａｃｔ１．０Ｔ超导扫描机,所用的扫描序列为脂肪抑制重Ｔ２ＳＥ序列。重建方法为均数重建法和最大信号强度投影（ＭＩＰ）法。结果：５０例ＭＲ椎管造影,２５例正常ＭＲ椎管造影都能清楚地显示硬膜囊、神经根、神经根鞘袖和椎旁静脉丛。２０例椎间盘突出症中轻度者３例,中度１７例,轻度表现为硬膜囊周围的静脉丛信号缺损     

Lumbar myelography: contrast agents used in the past, present, and future

With today's advanced technology and research, we have come a long way in the development of contrast agents used for lumbar myelography. Pantopaque was replaced by metrizamide, a more advanced contrast agent. Now iohexol, an even safer contrast material, may be the ideal radiographic agent of the future.     

Organ-specific effects of oxygen and carbogen gas inhalation on tissue longitudinal relaxation times.

Molecular oxygen has been previously shown to shorten longitudinal relaxation time (T1) in the spleen and renal cortex, but not in the liver or fat. In this study, the magnitude and temporal evolution of this effect were investigated. Medical air, oxygen, and carbogen (95% oxygen/5% CO2) were administered sequentially in 16 healthy volunteers. T1 maps were acquired using spoiled gradient echo sequences (TR=3.5 ms, TE=0.9 ms, alpha=2 degrees/8 degrees/17 degrees) with six acquisitions on air, 12 on oxygen, 12 on carbogen, and six to 12 back on air. Mean T1 values and change in relaxation rate were compared between each phase of gas inhalation in the liver, spleen, skeletal muscle, renal cortex, and fat by one-way analysis of variance. Oxygen-induced T1-shortening occurred in the liver in fasted subjects (P<0.001) but not in non-fasted subjects (P=0.244). T1-shortening in spleen and renal cortex (both P<0.001) were greater than previously reported. Carbogen induced conflicting responses in different organs, suggesting a complex relationship with organ vasculature. Shortening of tissue T1 by oxygen is more pronounced and more complex than previously recognized. The effect may be useful as a biomarker of arterial flow and oxygen delivery to vascular beds.     

The hazards of myelography.

The history of myelography and reactions to various contrast media is reviewed. Air is completely absorbed without producing long-term side effects. Lipiodol and Pantopaque are not absorbed and residual medium in the spinal canal can cause arachnoiditis. Other agents as Diodrast and Thorotrast never gained widespread acceptance. The water-soluble Dimer-X and Conray 60 have come into prominence but they are not totally without reactions. Recently a new water-soluble nonionic contrast medium has been developed in Norway. Metrizamide (Amipaque) has the same overall density as other water-soluble media but produces fewer reactions.     

AUR memorial award--1988. MRI enhancement of perfused tissues using chromium labeled red blood cells as an intravascular contrast agent

It has been demonstrated that chromium (Cr) labeling significantly decreases the relaxation times of packed red blood cells (RBCs). In this study, the spin-lattice relaxation time (T1) of human red cells was shortened from 836 ms to 29 ms and the spin-spin relaxation time (T2) shortened from 134 ms to 18 ms, when the cells were labeled at a Cr incubation concentration of 50 mM. Labeling of canine cells at 50 mM resulted in a T1 of 36 ms and a T2 of 26 ms. A labeling concentration of 10 mM produced similar relaxation enhancement, with uptake of 47% of the available Cr, and was determined to be optimal. The enhancement of longitudinal and transverse relaxation rates (1/T1,-1/T2) per amount of hemoglobin-bound Cr are 6.9 s-1 mM-1 and 9.8 s-1 mM-1 respectively, different from those of a pure Cr+3 solution. Labeling cells at 10 mM decreased the survival half-time in vivo from 16.6 days to 4.7 days in dogs. No difference in red cell survival was found with the use of hetero-transfusion versus auto-transfusion of labeled RBCs. Significant shortening of the T1 (912 ms to 266 ms, P = .03) and T2 (90 ms to 70 ms, P = .006) of spleen and the T1 (764 ms to 282 ms, P = .005) and the T2 (128 ms to 86 ms, P = .005) of liver occurred when 10% of the RBC mass of dogs was exchanged with Cr labeled cells. Liver and spleen spin density changes (P greater than 0.23) and muscle spin density and relaxation changes (P greater than 0.4) were insignificant. The in vivo T1 of a canine spleen which had been infarcted did not change following transfusion with labeled cells, where the T1 of liver did shorten. We believe this preliminary study suggests that Cr labeled red cells may have the potential to become an intravascular magnetic resonance imaging contrast agent.     

MR脊髓成像术的临床应用

目的：探讨重Ｔ２加权ＭＲ脊髓成像的临床应用价值。材料与方法：用重Ｔ２加权ＭＲ水成像技术做脊髓造影６３例，采用三维（３Ｄ）快速自旋回波（ＦＳＥ）和脂肪抑制序列，所有图像经三维最大信号强度投影（ＭＩＰ）后处理。结果：临床检查６３例中阳性４０例，阴性２３例。用此技术可获得高质量的图像，清楚地展示鞘膜囊缘、神经根和神经根鞘，并展示各种不同疾病的异常改变。结论：重Ｔ２加权ＦＳＥ序列ＭＲ脊髓成像是可靠的、非侵袭性的检查方法，它可代替常规Ｘ线脊髓造影和ＣＴ脊髓造影。     

Anterior and posterior lobes of the pituitary gland: assessment by 1.5 T MR imaging

Pituitary glands of 60 normal volunteers (30 men 20-36 years old, and 30 women 18-42 years old) were studied by 1.5 T magnetic resonance (MR) imaging. The T1-weighted images (T1WI) [repetition time (TR) = 400 ms; echo time (TE) = 25 ms] were obtained in the coronal, sagittal, and axial planes. Proton density (PD)/T2-weighted images (PDWI/T2WI) (TR = 2,000 ms; TE = 25/100 ms) were obtained in the sagittal plane using 3 mm slice thickness. On T1WIs of all subjects the posterior part (PP) of the pituitary fossa showed the highest signal, which was indistinguishable from fatty tissue. This study reveals that this region of high signal intensity (PP) corresponds to the posterior lobe and not intrasellar fat because its shape, size, and position are compatible with the posterior lobe; its signal intensity differs from that of fatty tissue on PDWI and T2WI; the absence of an intrinsic chemical shift artifact (CSA) characteristic of fat; and due to CSA, a dorsum with fatty marrow is shifted relative to the PP (or may be made to merge with it). Regarding the differentiation of the two lobes of the pituitary gland on MR, the morphology of the anterior and posterior lobes was evaluated and great variation found. Appreciation of normal is particularly important in evaluating coronal images for small pituitary lesions.     

Three-dimensional MR myelography of the lumbar spine: comparative case study to X-ray myelography

Conventional myelography was compared with a new type of MR technique using a fat-suppressing 3D fast imaging with steady precession (FISP) sequence for diagnosis of the lumbar root compression syndrome. 80 patients with discogenic disease in the lumbar spine were examined with a 1.0-T whole-body MR system (Siemens Magnetom Impact, Erlangen, Germany). A strongly T2^*-weighted 3D FISP sequence was applied in the sagittal orientation. To obtain fat suppression, a frequency-selective 1-3-3-1 prepulse was applied prior to the imaging sequence. The acquired 3D data set was evaluated using a maximum intensity projection (MIP) program. The measurement time was 7 min, 47 s. Magnetic resonance myelography has significant advantages over conventional myelography, particularly in cases of extreme spinal canal stenosis. Compared with the conventional method, this new MR technique shows comparable sensitivity in the visualization of the spinal nerve roots in the lumbar spine.     

Acute cervical spine trauma: evaluation with 1.5-T MR imaging

Twenty-one patients with acute neurologic deficits following cervical spine trauma were evaluated with magnetic resonance (MR) imaging (n = 21), computed tomography enhanced with intrathecal contrast material (CT myelography) (n = 18), myelography (n = 13), cervical spine radiography (n = 21), and intraoperative sonography (n = 7). MR imaging proved superior to other modalities in demonstrating parenchymal spinal cord injuries and cervical intervertebral disk herniation. Although both T1- and T2-weighted studies appear necessary to evaluate the anatomic relationship of the spinal cord, thecal space, intervertebral disks, and surrounding osseous and ligamentous structures, T2-weighted sequences were more sensitive than T1-weighted studies for detection of spinal cord injury. CT myelography was superior to MR imaging in demonstrating cervical spine fractures. In most cases, myelography revealed no information that was not apparent from both CT and MR imaging studies. Preliminary experience with MR imaging of acute cervical spine trauma suggests that it should be the study of choice in symptomatic patients who are otherwise clinically stable. CT may still be required in selected patients to evaluate complex fractures.     

Pantopaque mimicking spinal lipoma: MR pitfall

We present a patient with an intraspinal, high-signal-intensity lesion in the lumbosacral region on T1-weighted magnetic resonance images and a thin line of signal void between this region and the CSF on T2-weighted images. These findings were interpreted initially as representing an extradural spinal lipoma. However, CT revealed an intrathecal collection of iophendylate (Pantopaque), which was subsequently removed via a lumbar puncture. The apparent separation of Pantopaque from the CSF (seen on T2-weighted images and interpreted as the dura) was probably caused by chemical shift artifact, chemical shift contour, and/or CSF motion artifact.