MR scanning of the acutely injured knee: Sensitive, but is it cost effective?

Although magnetic resonance (MR) imaging has been established as an accurate diagnostic modality for knee pathology, the cost-effectiveness of this test is not known. In this investigation, we formulated a mathematical equation to assess cost-effectiveness and then used this formula to evaluate the use of knee MR as a diagnostic modality in acute knee injuries. We analyzed 105 consecutive MR scans performed at an imaging center with a diverse referral base, and identified 63 patients who had had symptoms for less than 6 months. Based on average regional medical costs, we calculated that diagnostic arthroscopy is more cost-effective than MR if 78% of the scanned patients eventually undergo arthroscopy. In our study population, 87% had arthroscopy after the MR scan. Therefore, in this patient cohort representing a diverse orthopedic community, arthroscopy alone would have been more cost-effective. Careful analysis in this type of cost-benefit framework would be beneficial and may lead to the establishment of objective criteria by which MR can be used in the most cost-effective manner.     

Magnetic resonance imaging compared with electrodiagnostic studies in patients with suspected carpal tunnel syndrome: predicting symptoms, function, and surgical benefit at 1 year

OBJECT: The goal in this study of patients with clinical carpal tunnel syndrome (CTS) was to compare the usefulness of magnetic resonance (MR) imaging with that of electrodiagnostic studies (EDSs) for the following purposes: 1) prediction of 1-year outcomes and 2) identification of patients who are likely to benefit from surgical treatment. METHODS: The authors prospectively enrolled 120 patients with clinically suspected CTS. The participants were tested using standardized EDSs, MR imaging, and a battery of questionnaires, including the Carpal Tunnel Syndrome Assessment Questionnaire, a well-validated 5-point score of symptoms and function. The EDSs and MR images were each interpreted independently. Patients were reevaluated after 1 year. The decision to treat patients conservatively or by carpal tunnel release was made by the individual surgeon, who had access to the initial EDS but not MR imaging results. Univariate and multivariate analyses were used to determine associations between 1-year outcomes and baseline diagnostic tests. RESULTS: The authors recontacted 105 of 120 participants at 12 months. Of these, 30 patients had had surgery and 75 had not. Patients who had undergone surgery showed greater improvement at 1 year than those who had not had surgery. The length of the abnormal T2-weighted nerve signal on MR imaging and median-ulnar sensory latency difference were the strongest predictors of surgical benefit. There was a clear patient preference for the MR imaging over EDSs. CONCLUSIONS: The findings obtained with MR imaging of the carpal tunnel predict surgical benefit independently of nerve conduction studies.     

Limiting breast surgery to the proper minimum

Clinical experience has resulted in the identification of a relatively small number of absolute contraindications to breast-conserving therapy (BCT). These contraindications are readily identified by a clinical evaluation and diagnostic mammography. Local failure rates of less than 10% at 10 years support the idea that patients can be reliably selected for BCT with standard clinical modalities. The availability of magnetic resonance (MR) imaging has raised questions about its role in patient selection for BCT. MR imaging identifies additional cancer in 10-54% of patients with apparently localized disease, resulting in mastectomies that would not otherwise have been done. Clinical experience suggests that the majority of this disease is controlled by radiotherapy. Studies demonstrating clinical benefit in terms of decreased rates of local recurrence or fewer surgeries are needed before MR is used for routine selection of patients for BCT.     

Three-tesla magnetic resonance imaging of the ventrolateral thalamus: a correlative anatomical description

OBJECT: Surgery for tremor targets the ventrolateral nuclei of the thalamus. An initial radiological estimation of this target can be further refined through intraoperative physiological confirmation. Direct visualization of these nuclei has not yet been described. The improved signal-to-noise ratio associated with 3-tesla (3T) magnetic resonance (MR) imaging makes increased spatial resolution possible, which may aid in the identification of subtle morphological features. This study was conducted to describe the anatomy of the nuclei and fiber projections within the ventral thalamus by using 3T MR imaging. METHODS: Using a commercially available 3T MR unit, the authors obtained images of a formalin-fixed, paraffin-embedded brain. Slices with a 2-mm thickness and 0.2-mm gap were obtained parallel to the anterior commissure-posterior commissure (AC-PC) line. The brain was then sectioned through the cerebral hemispheres to obtain tissue slices encompassing the same levels. Adjacent 10-microm paraffin sections from the middle of each level were stained with Luxol fast blue and cresyl violet. The MR image and histological sections at the level of the AC-PC line were then compared in detail. In a separate study, the human thalamus was scanned in vivo using 3T and 1.5T MR imaging for anatomical comparison. CONCLUSIONS: The anatomy of the nuclei and fiber projections within the ventrolateral thalamus in humans can be described using 3T MR imaging. The findings were reproducible in vivo with 3T but not 1.5T MR imaging. Additional studies are needed to confirm the accuracy of this observation for clinical purposes.     

Magnetic resonance imaging of the thyroid, thymus, and parathyroid glands

Magnetic resonance (MR) images of the neck were obtained in 16 patients with use of a variety of spin echo and inversion recovery pulse sequences. Anatomic resolution was best with high-resolution spin echo images obtained with the pulse sequence repetition rate equal to 2.0 seconds and the echo delay equal to 28 msec because this imaging technique offered excellent contrast between normal tissues and had the highest signal noise ratio. The spatial resolution of MR was nearly as good as state of the art computerized tomography (CT). However, streak artifacts caused by motion and x-ray beam hardening often limited CT but did not affect MR. Tumors and lymph nodes were more easily differentiated from muscle and blood vessels with MR than with CT because of the superior soft-tissue contrast of MR. Tissue characterization allowed MR differentiation of thyroid nodules, thyroid cysts, and parathyroid tumors from normal thyroid tissue. Thyroid cyst fluid had the greatest water content and longest T1 and T2 relaxation times of all tissues studied. However, nonspecifically increased T1 and T2 relaxation times overlapped for a variety of neoplastic and inflammatory conditions. With further experience, MR imaging is likely to become a useful technique for the evaluation of neck masses.     

Comparison of stereotactic brain biopsy to interventional magnetic-resonance-imaging-guided brain biopsy

Lesions within the brain are commonly sampled using stereotactic techniques. The advent of interventional magnetic resonance (MR) imaging now allows neurosurgeons to interactively investigate specific regions with exquisite visualization. We compared the safety and efficacy of this new surgical approach with stereotaxis. From February 1991 to June 1998, 134 stereotactic and 35 interventional MR-guided brain biopsies were performed. Stereotactic biopsies utilized preoperative scanning. Interactive scanning was used to confirm accurate positioning of the biopsy needle within the region of interest. Intraoperative pathologic examination of biopsy material was performed to verify the presence of diagnostic tissue in both biopsy groups. Intra- and postoperative MR imaging was obtained to exclude the presence of intraoperative hemorrhage. Recently, MR spectroscopic targeting has been utilized in 6 patients. In the stereotactic group, 129/134 (96%) biopsies were diagnostic. One patient had a transient hemiparesis after a brain stem biopsy and another suffered a fatal hemorrhage for a morbidity rate of 0.7% and a mortality rate of 0.7%. In reviewing 7,471 stereotactic biopsies, the morbidity was 3.5%, mortality 0.7% and diagnostic yield 91%. All 35 MR-guided brain biopsies were diagnostic (100%). MR spectroscopy was accurate in all cases in distinguishing recurrent tumor (5 cases) from radiation necrosis (1 case). One patient (3%) suffered a transient hemiparesis following a pontine biopsy and another patient (3%) developed a postoperative scalp cellulitis. No patient sustained a clinically or radiologically significant hemorrhage as determined by the immediate postbiopsy, intraoperative MR imaging. Interventional MR-guided brain biopsy is a safe and effective technique for evaluating lesions of the brain with morbidity and mortality rates comparable to those of stereotaxis. MR-guided biopsy appears to have a higher diagnostic yield than stereotaxis, which may reflect the ability to perform interactive, intraoperative scanning with that technique.     

Two cases of retained foreign bodies after cholecystectomy: diagnosis by sonography, CT, angiography, and MRI.

We encountered two cases of subphrenic abscesses around surgical sponges that had been left at cholecystectomy. These cases had been operated on either eight years or seven years earlier, respectively. These lesions resembled another diseases, especially, liver tumors. In order to make a differential diagnosis, various diagnostic procedures were carried out. Sonography showed a cystic mass with spongiform structures in one case. But in another case, no information of internal structures could be obtained because of the presence of a calcified wall. On CT, the lesions appeared as either round or elliptic masses that contained calcified foci in both cases. Angiography showed the extended and compressed branches of the hepatic artery. Spotty stains were also observed in one case. This appearance resembled a hepatic tumor. MR demonstrated both T1 and T2 elongated masses. The internal structures of the mass were clearly revealed by the improved version of the MR machine. MR proved to be extremely useful in making a differential diagnosis. It is, however, important to evaluate the findings of these imaging procedures synthetically and in association with a careful review of a patient's prior surgical history.     

Detection of hyperacute subarachnoid hemorrhage of the brain by using magnetic resonance imaging

OBJECT: The purpose of this study was to determine the diagnostic accuracy of high-field (1.5-tesla) magnetic resonance (MR) imaging in the assessment of hyperacute (< 12 hours after onset of symptoms) subarachnoid hemorrhage (SAH). METHODS: This investigation included 13 patients who were examined 2 to 12 hours posthemorrhage by using an MR imaging protocol consisting of T2-weighted and proton-density (PD)-weighted images, T1-weighted images, fast echoplanar-diffusion-weighted (EP-DW) images, and fluid-attenuated inversion-recovery (FLAIR) images. Subarachnoid hemorrhage had been diagnosed using computerized tomography (CT) scanning in all cases. In all 13 cases, SAH was reliably detected on both PD-weighted and FLAIR images. In contrast with FLAIR studies, the PD-weighted images were free of cerebrospinal fluid flow artifacts. The SAH was detected on T1-weighted images in only two cases and could not be detected on any T2-weighted or EP-DW images. CONCLUSIONS: Even hyperacute SAH can be diagnosed reliably from high-field MR images obtained using PD-weighted or FLAIR sequences. Use of these sequences in an emergency MR protocol may preclude the need for additional CT studies to rule out SAH.     

Clinical value of magnetic resonance imaging of the knee

Background : Magnetic resonance (MR) imaging is an accurate imaging modality of the knee. The role of MR in clinical practice has not been precisely defined, largely due to the relative expense of the technique. Methods : For each new patient with a knee problem who was referred for MR, a provisional diagnosis was made together with a level of certainty regarding the diagnosis. The waiting time for the scan was recorded. To assess clinical usefulness the MR diagnosis was compared with the provisional diagnosis and classified according to the following descending order of value: unexpected negative (no intra‐articular pathology), confirmatory negative, unexpected positive or confirmatory positive. To assess accuracy of the MR diagnosis, the operative diagnosis was compared to the MR diagnosis in those patients who underwent arthroscopy. Results : Fifty‐two per cent of scans were assessed as being very useful and a further 20% were assessed as being moderately useful. Magnetic resonance had a 95% accuracy for medial meniscal tears, 91% accuracy for lateral meniscal tears, and 98% accuracy for anterior cruciate ligament tears, similar to previously reported studies. The diagnostic arthroscopy rate in the patients who underwent MR scanning was similar to that in patients for whom the surgeon was more confident about the diagnosis and who therefore did not undergo MR scanning. The diagnostic arthroscopy rate could have been reduced if surgery had not been performed in 14 patients who had a negative MR scan. Conclusions : There is a role for selective use of MR in the assessment of knee conditions. In particular, MR can be used to reduce the diagnostic arthroscopy rate.     

Visualization of intraneural edema using gadolinium-enhanced magnetic resonance imaging of carpal tunnel syndrome

Background  In general, carpal tunnel syndrome (CTS) is diagnosed based mainly on clinical findings and electrophysiology. However, the pathological state of the compressed median nerve could not be shown on imaging. Gadoliniumenhanced magnetic resonance (MR) imaging may give us an idea about the status of the blood-nerve barrier of peripheral nerves. Therefore, detecting intraneural edema may be a way of diagnosing entrapment neuropathy. The present study investigated the diagnostic role of gadolinium-enhanced MR imaging of CTS. Methods  The subjects were 23 patients (34 hands) with idiopathic CTS. To serve as control subjects, 12 wrists of asymptomatic volunteers were studied. Using the spin-echo method, T1- and T2-weighted axial MR images were obtained. Intravenously injected gadolinium was used to obtain enhanced images. We studied the relation between nerve enhancement and the symptomatology. Results  After intravenous injection of gadolinium, there was no enhancement of the unaffected nerves in the carpal tunnels of the control group. Gadolinium enhancement was found in only 87% of patients with CTS who visited the hospital at an early stage and therefore had no nerve deficiency on electrophysiological studies (39%). Based on this finding, during the early stages when the nerve is in a state of neuropraxia, gadolinium-enhanced MR imaging of the median nerve might prove to be the most sensitive modality for detecting early nerve dysfunction. MR imaging also revealed a higher frequency of enhancement in the advanced stage of CTS with muscle atrophy. Conclusions  We conclude that gadolinium-enhanced MR imaging can detect not only morphological changes but also pathological changes of the median nerve in patients with CTS. Currently, gadolinium-enhanced-MR imaging is probably most commonly used to image patients who have ambiguous electrodiagnostic studies and clinical examination in an early stage of CTS.     

Can MRI predict meningioma consistency?: a correlation with tumor pathology and systematic review

Tumor consistency is a critical factor that influences operative strategy and patient counseling. Magnetic resonance imaging (MRI) describes the concentration of water within living tissues and as such, is hypothesized to predict aspects of their biomechanical behavior. In meningiomas, MRI signal intensity has been used to predict the consistency of the tumor and its histopathological subtype, though its predictive capacity is debated in the literature. We performed a systematic review of the PubMed database since 1990 concerning MRI appearance and tumor consistency to assess whether or not MRI can be used reliably to predict tumor firmness. The inclusion criteria were case series and clinical studies that described attempts to correlate preoperative MRI findings with tumor consistency. The relationship between the pre-operative imaging characteristics, intraoperative findings, and World Health Organization (WHO) histopathological subtype is described. While T2 signal intensity and MR elastography provide a useful predictive measure of tumor consistency, other techniques have not been validated. T1-weighted imaging was not found to offer any diagnostic or predictive value. A quantitative assessment of T2 signal intensity more reliably predicts consistency than inherently variable qualitative analyses. Preoperative knowledge of tumor firmness affords the neurosurgeon substantial benefit when planning surgical techniques. Based upon our review of the literature, we currently recommend the use of T2-weighted MRI for predicting consistency, which has been shown to correlate well with analysis of tumor histological subtype. Development of standard measures of tumor consistency, standard MRI quantification metrics, and further exploration of MRI technique may improve the predictive ability of neuroimaging for meningiomas.     

A pneumatized anterior clinoid mimicking an aneurysm on MR imaging. Report of two cases

The advent of magnetic resonance (MR) imaging has marked a new era in neuroimaging--particularly in terms of diminishing the need for more invasive diagnostic procedures. A cautionary note should be sounded, however, about an important limitation of standard spin-echo MR studies. Two patients were referred for angiography because MR imaging indicated the presence of a "paraclinoid aneurysm." In retrospect, these findings were due instead to a pneumatized anterior clinoid. Angiography could have been avoided had this pitfall been recognized, and had a gradient-echo flow-imaging protocol been utilized. This latter approach (which does not replace spin-echo imaging) is more sensitive to flowing blood and thus allows differentiation of an air space from a nonthrombosed aneurysm.     

Staging urinary bladder cancer with dynamic MR imaging

This article reviews the magnetic resonance (MR) staging of bladder cancer. The multiplanar and soft-tissue characterization capabilities of MR imaging make it a valuable diagnostic tool to image the urinary bladder. Recent advances of MR imaging such as fast imaging, pelvic phased array coil, and dynamic imaging improve the image quality and diagnostic accuracy for staging bladder cancer. Some patient-related factors are also important for optimal imaging of the urinary bladder, especially motion artifacts from the gastrointestinal tract and the degree of bladder distension. An anticholinergic agent should be used for suppressing the motion artifacts. Optimal bladder filling can be achieved by asking patients to void and drink water 1 hour before examinations. Scanning perpendicular to the bladder wall is necessary for optimal evaluation for staging bladder cancer. Oblique scanning is needed in cases when a tumor is not located on the dome, base, anterior wall, posterior wall, or lateral walls. The early phase image of dynamic imaging is most useful for staging tumors. Better contrast between tumor and bladder wall on dynamic images provides high staging accuracy, especially in differentiation between superficial tumors and tumors with muscle invasion. MR imaging is comparable to computed tomography (CT) in the evaluation of lymph nodes. Although MR imaging currently is not appropriate for screening for bladder cancer and detecting small tumors, it has been proved to be most useful in the staging of bladder cancer.     

Two cases of retained foreign bodies after cholecystectomy: Diagnosis by sonography,CT, angiography,and MRI

We encountered two cases of subphrenic abscesses around surgical sponges that had eeen left at cholecystectomy. These cases had been operated on either eight years or seven years earlier, respectively. These lesions resembled another diseases, especially, liver tumors. In order to make a differential diagnosis, various diagnostic procedures were carried out. Sonography showed a cystic mass with spongiform structures in one case. But in another case, no information of internal structures could be obtained because of the presence of a calcified wall. On CT, the lesions appeared as either round or elliptic masses that contained calcified foci in both cases. Angiography showed the extended and compressed branches of the hepatic artery. Spotty stains were also observed in one case. This appearance resembled a hepatic tumor. MR demonstrated both T1 and T2 elongated masses. The internal structures of the mass were clearly revealed by the improved version of the MR machine. MR proved to be extremely useful in making a differential diagnosis. It is, however, important to evaluate the findings of these imaging procedures synthetically and in association with a careful review of a patient's prior surgical history.     

Diagnostic neuroimaging by magnetic resonance imaging: update

Magnetic resonance (MR) imaging remains the most versatile technique in diagnostic imaging. In addition to conventional imaging sequences such as T(1)-weighted imaging, T(2)-weighted imaging, or fluid-attenuated inversion recovery imaging, various techniques specific for certain pathological conditions are being continuously introduced. Pulse sequences for various imaging contrasts are becoming mature, and studies on high (3 T), or even ultra-high (7 T) field systems are emerging as a golden standard for neurosurgical practices. MR spectroscopic imaging capable of providing a pictorial display of the chemical properties of the brain and microscopic imaging providing images with significantly high anatomical resolution equivalent to histological preparations are now becoming essential for presurgical evaluation.     

Detection of articular defects using magnetic resonance imaging: an experimental study

This study evaluates magnetic resonance imaging (MRI) in the detection of surgically created articular defects in bovine knees. A total of 26 articular defects was created in 2 fresh cadaveric cows' knees. The defects created include chondromalacic grade 2 defects, chondral and osteochondral defects from 3 to 15 mm in diameter. The knee joints were repaired in a normal saline bath to exclude air in the joint prior to MR scanning. T1 weighted spin echo (SE) images and 3D gradient echo (FISP 40 degrees 3D) images were obtained. The T1 weighted SE imaging technique detected 15 defects (57.7%) compared with FISP 3D imaging technique detection of 17 defects (65.4%). The two techniques combined enable 21 of 26 defects (80.8%) to be detected. The imaging techniques used in this study were not able to detect chondromalacic defects less than 10 mm in diameter, nor chondral defects less than 5 mm in diameter. However, small osteochondral defects of 3 mm in diameter are detectable provided the depth of the defect is not less than 10 mm. The FISP 3D imaging technique alone is more sensitive in detecting chondral defects. Both imaging techniques have similarly high sensitivities in detecting osteochondral defects. The imaging time for combined T1 weighted SE and FISP 3D sequence is short (16.5 mm) and this combined technique may be useful for MR scanning of knee joints suspected to have articular defects.     

Three-dimensional constructive interference in steady-state magnetic resonance imaging in syringomyelia: advantages over conventional imaging

OBJECT: Neuroradiology has become indispensable in detecting the pathophysiology in syringomyelia. Constructive interference in steady-state (CISS) magnetic resonance (MR) imaging can provide superior contrast at the sub-arachnoid tissue borders. As this region is critical in preoperative evaluation, the authors hypothesized that CISS imaging would provide superior assessment of syrinx pathology and surgical planning. METHODS: Based on records collected from a database of 130 patients with syringomyelia treated at the authors' institution, 59 patients were prospectively evaluated with complete neuroradiological examinations. In addition to routine acquisitions with FLAIR, T1- and T2-weighted, and contrast-enhanced MR imaging series, the authors obtained sagittal cardiac-gated sequences to visualize cerebrospinal fluid (CSF) pulsations and axial 3D CISS MR sequences to detect focal arachnoid webs. Statistical qualitative and quantitative evaluations of spinal cord/CSF contrast, spinal cord/CSF delineation, motion artifacts, and artifacts induced by pulsatile CSF flow were performed. RESULTS: The 3D CISS MR sequences demonstrated a contrast-to-noise ratio significantly better than any other routine imaging sequence (p < 0.001). Moreover, 3D CISS imaging can detect more subarachnoid webs and cavitations in the syrinx than T2-weighted MR imaging with less flow-void artifact. The limitation of 3D CISS imaging is a susceptibility to motion artifacts that can cause reduced spatial resolution. Lengthy acquisition times for axial segments can be reduced with multiplanar reconstruction of 3D CISS-generated sagittal images. CONCLUSIONS: Constructive interference in steady-state imaging is the MR sequence of choice in the preoperative evaluation of syringomyelia, allowing significantly higher detection rates of focal subarachnoid webs, whereas standard T2-weighted MR imaging shows turbulent CSF flow voids. Constructive interference in steady-state MR imaging enables the neurosurgeon to accurately identify cases requiring decompression for obstructed CSF. Motion artifacts can be eliminated with technical variations.     

Diagnostic usefulness of endorectal magnetic resonance imaging with dynamic contrast-enhancement in patients with localized prostate cancer: Mapping studies with biopsy specimens

BACKGROUND: New diagnostic criteria for dynamic magnetic resonance (MR) imaging in prostate cancer are presented. The diagnostic usefulness of endorectal MR imaging with dynamic contrast-enhancement in localized prostate cancer and the validity of these criteria were evaluated. METHODS: Eighteen untreated patients who were suspected of localized prostate cancer were included in the study. They received endorectal dynamic MR imaging before systematic sextant needle biopsy. First. a mapping study with the findings of MR images and histopathology of biopsy specimens was performed in eight patients out of 18 to compare the difference in T2-weighted images with the endorectal coil and the body coil in the same individuals. Second, another mapping study was performed in all 18 patients by analyzing the findings of endorectal dynamic MR images. For the diagnosis of prostate cancer in MR imaging, we offered diagnostic criteria from our experience in addition to those in plain T2-weighted images from the literature. RESULTS: The overall diagnostic rates of endorectal dynamic MR imaging were 88.9% in accuracy, 100% in sensitivity, and 81.8% in specificity. In the comparison of the endorectal and body coils in T2-weighted images in eight patients, there was no difference in the diagnostic rates except for one more histopathologic false positive portion in endorectal MR imaging. In the second mapping study in 18 patients, the diagnostic rates were 92.6% in accuracy, 88.9% in sensitivity and 93.3% in specificity. Endorectal dynamic imaging raised the diagnostic sensitivity from 77.8 to 88.9%. CONCLUSION: The data demonstrated the validity of this diagnostic criteria and the diagnostic usefulness of endorectal dynamic MR imaging in localized prostate cancer.     

Magnetic resonance imaging contrast agents: theory and application to the central nervous system

The theoretical aspects of magnetic resonance (MR) imaging contrast agents are reviewed, and their current applications to the central nervous system (CNS) and their future applications are discussed. Profound differences exist between contrast agents used for MR imaging and computerized tomography (CT). In MR imaging, the contrast agents are not imaged directly but rather act on adjacent protons to shorten T1 and T2 relaxation times. This in turn results in signal intensity changes. The lanthanide metal, gadolinium, in the form of gadopentetate dimeglumine, has been found to be both safe and efficacious as the only currently approved contrast agent for MR imaging. Magnetic resonance imaging revolutionized the detection and treatment of disease affecting the brain and spine. Initially, it was thought that signal characteristics on MR imaging would allow differentiation of specific pathology. It was soon found that MR studies were able to detect more abnormalities but were less able to characterize them. The recent development of contrast agents for MR imaging has allowed this modality to surpass CT for the evaluation of most CNS lesions. At present, contrast-enhanced MR imaging is generally accepted as the study of choice for evaluating acoustic neurinomas, pituitary lesions, meningeal disease, primary and secondary brain tumors, active multiple sclerosis, intradural spinal neoplasms, intramedullary spinal disease, and postoperative states in both the spine and brain. Even when contrast-enhanced CT can detect the same abnormalities, evaluation of the lesions in multiple planes on MR imaging can sometimes yield invaluable information, especially prior to surgery. Future developments of contrast material for MR imaging include non-gadolinium compounds, intrathecal contrast media, cerebral blood flow and volume evaluation, and, possibly, antibody-labeled contrast agents.     

Rathke cleft cyst intracystic nodule: a characteristic magnetic resonance imaging finding

OBJECT: The fluid content of Rathke cleft cysts (RCCs) displays variable appearances on magnetic resonance (MR) images and can appear indistinguishable from other intrasellar or suprasellar cystic lesions. Intracystic nodules associated with individual RCCs have been noted, but to date their significance has not been fully explored. METHODS: The authors retrospectively reviewed MR imaging studies obtained in patients harboring intrasellar or suprasellar lesions that were consistent with RCCs to identify the presence and imaging characteristics of intracystic nodules. An intracystic nodule was present in nine (45%) of 20 patients with an RCC. All intracystic nodules were clearly visible and displayed a characteristic low signal intensity on T2-weighted MR images. The nodule was only visualized on T1-weighted images in four cases, in which it exhibited a consistent high signal intensity similar to that of the cyst fluid. The nodules did not enhance following the intravenous administration of a contrast agent. CONCLUSIONS: Although it is difficult to differentiate RCCs from other sellar cystic lesions because of the variable signal intensities displayed on MR images, the intensity of the intracystic nodule seems consistent on T1- and T2-weighted images, and the nodule is always clearly visible on T2-weighted images. With a nonenhancing cystic lesion that does not cause significant symptoms in the patient, the identification of an intracystic nodule with a characteristic signal intensity will aid in the diagnosis of RCC and the selection of conservative management.