Standard Magnetic Resonance Imaging Techniques Research Articles

A comprehensive MRI analysis of osteoid osteomas in patients with diverse radiological features across various regions.

Magnetic resonance imaging (MRI), which does not involve ionizing radiation, is the preferred imaging modality for diagnosing osteoid osteoma (OO), an ailment more common in children and young adults. This study aims to perform a literature review and delineate the MRI findings of OO lesions in patients exhibiting varying radiological features across different regions. A retrospective study included 63 patients diagnosed with OO through MRI, assessed independently by two blinded radiologists using both standard and dynamic contrast-enhanced MRI techniques. After excluding 7 patients with prior biopsy, surgery, or RFA, the study included 56 patients with 57 lesions. Of 57 lesions evaluated, 50 were in long, and 7 in flat bones. One patient presented with two separate nidi within the intertrochanteric region. Most of the lesions, 49 (86%), were extra-articular, while 8 (14%) were intra-articular. The nidus was intracortical in 45 (78.9%) patients, intramedullary in 5 (8.8%), subperiosteal in 5 (8.8%), and endosteal in 2 (3.5%). Average nidus diameter was 7.02 ± 2.64 mm (3-12.6 mm). Central nidal calcification was present in 68.4% (n = 39) cases. Contrast enhancement was intense at 90.5%, moderate at 9.5%. Reactive sclerosis around the nidus was severe (50.9%), moderate (22.8%), and mild (26.3%). Bone marrow edema was severe (70.2%), moderate (14.0%), and mild (15.8%). Soft tissue edema was identified in 77.2% of all lesions. To minimize delays in diagnosis and treatment, radiologists should become acquainted with the typical OO MRI findings and the atypical MRI findings that might be mistaken for other conditions.

Susceptibility-weighted MR imaging to improve the specificity of erosion detection: a prospective feasibility study in hand arthritis.

To evaluate the diagnostic potential of susceptibility-weighted imaging (SWI) for the detection of erosions of the hand, compared to T1-weighted (T1w) magnetic resonance imaging (MRI). Computed tomography (CT) was used as a reference standard. We prospectively investigated 37 patients with suspected arthritic activity of the hand. All patients underwent T1w, SWI, and CT on the same day. Patients were randomized to MRI or CT first. CT, T1w, SWI, and T1w/SWI were scored for erosions according to OMERACT RAMRIS guidelines. Specificity, sensitivity, and diagnostic accuracy were separately calculated for T1w, SWI, and T1w/SWI on a per-patient and per-bone basis using CT as reference. The one-tailed McNemar test was performed to test the number of erosion-positive patients in T1w, SWI, and T1w/SWI for non-inferiority. Measured erosion sizes were compared using Pearson's test. CT was positive for erosions in 16 patients and 55 bones. SWI and T1w/SWI had superior diagnostic accuracy (91.2 and 93.8%) compared to T1w (87.8%) driven by a higher specificity (93.8 and 96.5%) compared to T1w (88.8%). On the patient level, SWI and T1w/SWI showed non-inferiority (p = 0.11 and p = 0.38) but not T1w alone (p < 0.0001). The lesion size on CT correlated better with SWI (Pearson's r = 0.92) compared to T1w (r = 0.69). Adding SWI to a standard MRI protocol has the potential to improve erosion detection in hands by increasing specificity. SWI depicts bony erosions more accurately compared to standard MRI techniques.

Free-breathing quantification of hepatic fat in healthy children and children with nonalcoholic fatty liver disease using a multi-echo 3-D stack-of-radial MRI technique

In adults, noninvasive chemical shift encoded Cartesian magnetic resonance imaging (MRI) and single-voxel magnetic resonance (MR) spectroscopy (SVS) accurately quantify hepatic steatosis but require breath-holding. In children, especially young and sick children, breath-holding is often limited or not feasible. Sedation can facilitate breath-holding but is highly undesirable. For these reasons, there is a need to develop free-breathing MRI technology that accurately quantifies steatosis in all children. This study aimed to compare non-sedated free-breathing multi-echo 3-D stack-of-radial (radial) MRI versus standard breath-holding MRI and SVS techniques in a group of children for fat quantification with respect to image quality, accuracy and repeatability. Healthy children (n=10, median age [±interquartile range]: 10.9 [±3.3] years) and overweight children with nonalcoholic fatty liver disease (NAFLD) (n=9, median age: 15.2 [±3.2] years) were imaged at 3 Tesla using free-breathing radial MRI, breath-holding Cartesian MRI and breath-holding SVS. Acquisitions were performed twice to assess repeatability (within-subject mean difference, MDwithin). Images and hepatic proton-density fat fraction (PDFF) maps were scored for image quality. Free-breathing and breath-holding PDFF were compared using linear regression (correlation coefficient, r and concordance correlation coefficient, ρc) and Bland-Altman analysis (mean difference). P<0.05 was considered significant. In patients with NAFLD, free-breathing radial MRI demonstrated significantly less motion artifacts compared to breath-holding Cartesian (P<0.05). Free-breathing radial PDFF demonstrated a linear relationship (P<0.001) versus breath-holding SVS PDFF and breath-holding Cartesian PDFF with r=0.996 and ρc=0.994, and r=0.997 and ρc=0.995, respectively. The mean difference in PDFF between free-breathing radial MRI, breath-holding Cartesian MRI and breath-holding SVS was <0.7%. Repeated free-breathing radial MRI had MDwithin=0.25% for PDFF. In this pediatric study, non-sedated free-breathing radial MRI provided accurate and repeatable hepatic PDFF measurements and improved image quality, compared to standard breath-holding MR techniques.

Three-dimensional Magnetic Resonance Imaging of the Anterolateral Ligament of the Knee: An Evaluation of Intact and Anterior Cruciate Ligament–Deficient Knees From the Scientific Anterior Cruciate Ligament Network International (SANTI) Study Group

To determine the visualization rate of the anterolateral ligament (ALL) in uninjured and anterior cruciate ligament (ACL)-deficient knees using 3-dimensional (3D) magnetic resonance imaging (MRI) and to characterize the spectrum of ALL injury observed in ACL-deficient knees, as well as determine the interobserver and intraobserver reliability of a 3D MRI classification of ALL injury. A total of 100 knees (60 ACL deficient and 40 uninjured) underwent 3D MRI. The ALL was evaluated by 2 blinded orthopaedic surgeons. The ALL was classified as follows: type A, continuous, clearly defined low-signal band; type B, warping, thinning, or iso-signal changes; and type C, without clear continuity. The comparison between imaging performed early after ACL injury (<1month) and delayed imaging (>1month) was evaluated, as was intraobserver and interobserver reliability. Complete visualization of the ALL was achieved in all uninjured knees. In the ACL-deficient group, 24 knees underwent early imaging, with 87.5% showing evidence of ALL injury (3 normal, or type A, knees [12.5%], 18 type B [75.0%], and 3 type C [12.5%]). The remaining 36 knees underwent delayed imaging, with 55.6% showing evidence of injury (16 type A [44.4%], 18 type B [50.0%], and 2 type C [5.6%]). The difference in the rate of injury between the 2 groups was significant (P= .03). Multivariate analysis showed that the delay from ACL injury to MRI was the only factor (negatively) associated with the rate of injury to the ALL. Interobserver reliability and intraobserver reliability of the classification of ALL type were good (κ= 0.86 and κ= 0.93, respectively). Three-dimensional MRI allows full visualization of the ALL in all normal knees. The rate of injury to the ALL in acutely ACL-injured knees identified on 3D MRI is higher than previous reports using standard MRI techniques. This rate is significantly higher than the rate of injury to the ALL identified on delayed imaging of ACL-injured knees. Level IV, diagnostic, case-control study.

BBB permeability as a magnetic resonance imaging biomarker for low glioblastoma infiltration

Detecting and measuring invasion of the normal brain is crucial for the successful treatment of glioblastoma (GBM) as it allows increasing the accuracy of target volume delineation for radiotherapy planning. Probing the integrity of the peritumoral Blood-Brain Barrier (BBB) could substantially facilitate drug delivery planning. While magnetic resonance imaging (MRI) is a valuable tool for clinicians treating GBM, standard imaging techniques fail to detect regions of low tumour cell density and provide poor information about subtle BBB permeability changes caused by GBM invasion. However, invading tumour cells often progress along blood vessels and recent results indicate that even individual cells can disrupt the normal BBB function, providing an opportunity to detect tumour invasion at its earliest stages. Our research focuses on the development of MRI techniques probing brain perfusion and BBB permeability, and their assessment as biomarkers for detecting low tumour infiltration regions in mouse GBM models presenting highly invasive tumour margins. A high SNR multiple boli Arterial Spin Labelling (mbASL) technique was optimised for rodent brain perfusion imaging and a diffusion-weighted ASL (DWASL) method was implemented for probing the molecular mobility of perfused blood water. Introducing diffusion gradients into the ASL sequence allows minimising the signal contribution of the fast motion “vascular component” providing with perfusion images dominated by the slower motion “tissue component”. The ratio of the “tissue component” perfusion images to the overall perfusion ones obtained by ASL was expected to produce BBB permeability-weighed maps. The resulting maps were compared with histological sections stained (FITC)-dextrans to assess BBB disruption. The ability of perfusion and BBB permeability techniques to characterise tumour invasion was evaluated by comparison with standard MRI techniques (T2W and DW) and immunohistochemistry sections cut in the MRI plane. Both techniques were shown to detect low tumour regions not detected by standard MRI techniques.

Abbreviated MRI and Accelerated MRI for Screening and Diagnosis of Breast Cancer.

Although published studies have revealed that magnetic resonance imaging (MRI) is by far the most effective imaging modality for cancer detection, it is currently considered cost-ineffective for screening women at an intermediate risk for breast cancer. The concept of an "abbreviated MRI" protocol has recently emerged as a possible solution for reducing the cost of MRI. The abbreviated MRI is a shortened version of the standard MRI, consisting of a single early phase dynamic contrast enhanced (DCE) series. Several clinical studies have shown that this MRI protocol would not affect sensitivity or specificity for breast MRI screening purposes. In clinical practice, morphologic evaluation and kinetic assessment are 2 major components of the interpretation process. However, kinetic assessment cannot be performed with the abbreviated protocol, because multiple sets of post-contrast images are necessary for the generation of kinetic curves. "Accelerated MRI" is a collective term for imaging techniques that acquire DCE-MR images in a very short time. Published studies suggest that the kinetic assessment during the very early post-contrast phase obtained with the accelerated MRI techniques is comparable to that with the standard MRI techniques. Applying accelerated MR techniques could potentially enhance the abbreviated MRI protocol in terms of diagnostic potential, while maintaining the shorter study time. Thus, the abbreviated MRI protocol associated with accelerated MRI techniques may provide value for screening and for diagnostic purposes.

Use of Diffusion Tensor Imaging in the Resection of Gliomas

Standard magnetic resonance imaging techniques provide only anatomic information without information regarding central nervous system connectivity. Overcoming this limitation, diffusion tensor imaging (DTI) can demonstrate the structural integrity and white matter tracts of the brain. In this paper, we will overview the basic principles and techniques of DTI. We will also review the application of DTI in neurosurgery, particularly its application in the resection of gliomas. Tractography provides visualization of the motor tracts and language tracts, which has been corroborated using subcortical mapping/direct stimulation. Furthermore, DTI can also provide information about the arrangement of visual fibers in relation to tumors. Given these advantages, DTI is becoming increasingly used as a surgical planning tool. DTI may provide a safer means for tumor resection by minimizing iatrogenic injury of important functional tracts. Some studies suggest that the use of DTI in tumor surgery may lead to greater Karnofsky performance status scores, greater extent of tumor resection, and increased overall survival.

Quantitative chemical-shift MR imaging cutoff value: Benign versus malignant vertebral compression – Initial experience

PurposeTo evaluate the diagnostic accuracy of in-phase/opposed-phase quantitative chemical shift magnetic resonance (MR) imaging of the spine and to determine the cutoff value that enables differentiation of malignant from benign compression fractures, in patients with known primary malignancy. Patients and methodsProspective assessment of thirty-two patients with known primary malignancy who presented with vertebral compression fractures, MR imaging of the spine at 1.5Tesla with standard conventional MR sequences and additional chemical shift (in-phase/opposed-phase) imaging was done. Quantitative image analysis by drawing regions of interest (ROI) on the abnormal marrow of compressed (study group) and adjacent normal vertebra (control group) was also performed in each patient. The signal intensity ratio (SIR) of the marrow was determined by dividing the mean signal intensity on the opposed-phase to the mean signal intensity on the in-phase images and statistical analysis was performed. ResultsMean SIR of benign vertebral compression [0.73±0.07 (range 0.12–1.2)] was significantly lower than malignant SIR values [1.72±0.14 (range 0.8–2.96)] (p<0.0001; area under the ROC curve, 0.97). The optimal SIR cutoff value for separating benign and malignant vertebral compression was found to be 0.91 with a calculated sensitivity of 93%, specificity of 82% and accuracy of 88%. ConclusionQuantitative chemical shift MR imaging could be a valuable addition to standard MR imaging techniques and represent a rapid problem solving tool in differentiating benign from malignant vertebral compression, especially in patients with known primary malignancies.

Storage of Hydrogen Spin Polarization in Long-Lived 13C2 Singlet Order and Implications for Hyperpolarized Magnetic Resonance Imaging

Hyperpolarized magnetic resonance imaging (MRI) is a powerful technique enabling real-time monitoring of metabolites at concentration levels not accessible by standard MRI techniques. A considerable challenge this technique faces is the T1 decay of the hyperpolarization upon injection into the system under study. Here we show that A(n)A'(n)XX' spin systems such as (13)C2-1,2-diphenylacetylene ((13)C2-DPA) sustain long-lived polarization for both (13)C and (1)H spins with decay constants of almost 4.5 min at high magnetic fields of up to 16.44 T without spin-locking; the T1 of proton polarization is only 3.8 s. Therefore, storage of the proton polarization in a (13)C2-singlet state causes a 69-fold extension of the spin lifetime. Notably, this extension is demonstrated with proton-only pulse sequences, which can be readily implemented on standard clinical scanners.

Morphological and functional evaluation of chronic pancreatitis with magnetic resonance imaging

Magnetic resonance imaging (MRI) techniques for assessment of morphology and function of the pancreas have been improved dramatically the recent years and MRI is very often used in diagnosing and follow-up of chronic pancreatitis (CP) patients. Standard MRI including fat-suppressed T1-weighted and T2-weighted imaging techniques reveal decreased signal and glandular atrophy of the pancreas in CP. In contrast-enhanced MRI of the pancreas in CP the pancreatic signal is usually reduced and delayed due to decreased perfusion as a result of chronic inflammation and fibrosis. Thus, morphological changes of the ductal system can be assessed by magnetic resonance cholangiopancreatography (MRCP). Furthermore, secretin-stimulated MRCP is a valuable technique to evaluate side branch pathology and the exocrine function of the pancreas and diffusion weighted imaging can be used to quantify both parenchymal fibrotic changes and the exocrine function of the pancreas. These standard and advanced MRI techniques are supplementary techniques to reveal morphological and functional changes of the pancreas in CP. Recently, spectroscopy has been used for assessment of metabolite concentrations in-vivo in different tissues and may have the potential to offer better tissue characterization of the pancreas. Hence, the purpose of the present review is to provide an update on standard and advanced MRI techniques of the pancreas in CP.

Conjoined nerve roots of the lumbar spine

Conjoined nerve roots are a relatively uncommon finding but are frequently undiagnosed on preoperative imaging studies. The presence of a conjoined root anomaly represents a significant potential for neurologic injury when nerve root mobilization is necessary during spinal procedures. This comprehensive review of conjoined lumbar nerve roots encompasses preoperative diagnosis by physical examination and radiographic imaging studies, as well as the intraoperative management of conjoined nerve roots. Systematic review of existing literature. Findings have been described on standard magnetic resonance imaging (MRI) and computed tomography imaging to increase preoperative diagnosis rates. The literature lacks concrete recommendations regarding intraoperative techniques for conjoined root identification and management. Preoperative recognition and diagnosis of this anomaly has proven to be the best way to improve the chances of a successful procedure and avoid inadvertently damaging the nerve roots intraoperatively. Several radiographic signs of conjoined lumbar nerve roots have been described using standard MRI techniques including coronal T1- and T2-weighted sequences. Intraoperative management of conjoined nerve roots has not changed significantly since they were first identified, although diagnostic accuracy has improved with advanced MRI techniques.

Interictal arterial spin-labeling MRI perfusion in intractable epilepsy

Magnetic resonance imaging (MRI) is required for the investigation of surgically intractable epilepsy. In addition to the standard MRI techniques, perfusion sequences can be added to improve visualization of underlying pathological changes. Arterial spin-labeling (ASL) MRI perfusion does not require contrast administration and, for this reason, may have advantages in these patients. We report here on 16 patients with epilepsy who underwent MRI of the brain with ASL and positron emission tomography (PET). Despite a slightly reduced resolution with ASL, we found a correlation between ASL, PET and electrophysiological data, with hypoperfusion on ASL that corresponded with hypoperfusion on interictal PET. Given the correlation between ASL and PET and electrophysiology, perfusion with ASL could become part of the standard work-up in patients with epilepsy.

Arterial spin-labeling MRI perfusion in tuberous sclerosis: Correlation with PET

Neuroimaging using magnetic resonance imaging (MRI) is required for the investigation of surgically intractable epilepsy. In addition to the standard MRI techniques, perfusion sequences can be added to improve visualization of the underlying pathological changes. Also, as arterial spin-labeling (ASL) MRI perfusion does not require contrast administration, it may even be advantageous in these patients. We report here on three patients with epilepsy and tuberous sclerosis who underwent brain MRI with ASL and positron emission tomography (PET), both of which were found to correlate with each other and with electrophysiological data.

Magnetic Resonance Imaging of Gallbladder and Biliary System

Gallbladder and biliary system pathologic component is a spectrum of benign and malignant conditions. Standard magnetic resonance imaging techniques when used together with magnetic resonance cholangiopancreatography (MRCP) can evaluate gallbladder and biliary system pathologic conditions. Inflammatory diseases are characterized by thickening and intense mucosal contrast enhancement of the affected bile ducts and or gallbladder wall. Postinflammatory changes can be appreciated on MRCP with short or long segment strictures of the bile ducts. Serial contrast-enhanced images show reactive inflammatory changes in the liver parenchyma. Neoplastic diseases of the gallbladder and the biliary tree are evaluated on T2-weighted fat-suppressed echo train and serial contrast-enhanced images and their obstructive effect can be displayed on MRCP images. In this paper, we will review the spectrum of MRI findings of gallbladder and biliary system pathologic conditions.

Magnetic Resonance Imaging in Pancreatitis

Pancreatitis can occur in acute and chronic forms. Magnetic resonance imaging (MRI) plays an important role in the early diagnosis of both conditions and complications that may arise from acute or chronic inflammation of the gland. Standard MRI techniques including T1-weighted and T2-weighted fat-suppressed imaging sequences together with contrast-enhanced imaging can both aid in the diagnosis of acute pancreatitis and demonstrate complications as pseudocysts, hemorrhage, and necrosis. Combined use of MRI and MR cholangiopancreatography can show both parenchymal findings that are associated with chronic pancreatitis including pancreatic size and signal and arterial enhancements, all of which are diminished in chronic pancreatitis. The degree of main pancreatic duct dilatation and/or the number of side branch ectasia determines the diagnosis of chronic pancreatitis and its severity. In this paper, we report the spectrum of imaging findings of acute and chronic pancreatitis on MRI and MR cholangiopancreatography.

MR Imaging of Cartilage Repair in the Knee and Ankle

Because of the relative avascularity of articular cartilage, lesions that are caused by trauma or degeneration of the cartilage do not heal spontaneously and must be repaired surgically. The interventional procedures that have been developed for the repair of such lesions include abrasion, microfracture, autologous osteochondral transplantation, allograft transplantation, and autologous chondrocyte implantation. An accurate imaging assessment of the repair tissue is necessary in order to objectively evaluate the postoperative outcome. Magnetic resonance (MR) imaging and arthroscopy provide complementary information and are especially useful for follow-up evaluation of cartilage repair in the knee and ankle. Standard MR imaging techniques may be used postoperatively to evaluate the success of implantation and the state of cartilage healing. Newer matrix assessment techniques, which include delayed gadolinium-enhanced MR imaging and mapping of T1rho and T2 values, may provide useful supplemental information about the histologic and biochemical contents of reparative tissue. The normal postoperative appearance of the joints after cartilage repair varies according to the surgical technique used and the stage of healing. To identify potential complications, it is important to be familiar with the various repair procedures and the characteristic MR imaging features of the repair tissue at various postoperative intervals.

Comparison of effects of different long-term iron-chelation regimens on myocardial and hepatic iron concentrations assessed with T2* magnetic resonance imaging in patients with β-thalassemia major

The aim of this study was to compare the effect of different long-term chelation regimens on heart and liver iron stores with the use of T2* magnetic resonance imaging (MRI) in patients with transfusion-dependent beta-thalassemia major. Sixty-four patients (28 men, 36 women; mean age, 26.49 +/- 5.8 years) were enrolled in the study. The 3 groups were based on the chelation therapy received. The first group (19 patients) received deferiprone (DFP) (75 mg/kg per day orally), the second group (23 patients) received deferoxamine (DFO) (30-50 mg/kg per day subcutaneously at least 5 times/week), and the third group (22 patients) received a combination of DFO (30-50 mg/kg per day, 2-3 days/week) and DFP (75 mg/kg per day, 7 days/week). MRI scans were acquired with an imager equipped with a 1.5 T magnet, and the data included myocardial and hepatic iron measurements obtained by means of T2*, and ventricular volumes and ejection fractions obtained with standard cardiovascular MRI techniques. The results revealed that the DFP and the combined groups had significantly less myocardial iron than the DFO group (mean myocardial T2*, 35.77 +/- 18.3 milliseconds and 38.05 +/- 15.3 milliseconds versus 23.77 +/- 13 milliseconds [P = .02, and P = .001], respectively). On the contrary, the DFP group had a significantly higher hepatic iron content than the DFO and combined groups (mean hepatic T2*, 3.29 +/- 2.5 milliseconds versus 8.16 +/- 8.4 milliseconds and 11.3 +/- 10.9 milliseconds [P = .014, and P = .003], respectively). No correlation was observed between myocardial T2* and hepatic T2* values (r = -0.043; P = .37). Myocardial T2* values were inversely correlated with age (r = -0.249; P = .024) and positively correlated with both left and right ventricular ejection fractions (r = 0.33 [P = .004], and r = 0.279 [P = .014], respectively). Finally, liver T2* was strongly and inversely correlated with serum ferritin concentration (r = -0.465; P = .001). In conclusion, combined chelation therapy seems to sum the beneficial effects of DFO and DFP with respect to hepatic and myocardial iron. Because myocardial iron is not related to measurements of serum ferritin or hepatic T2*, important decisions on clinical management relating to cardiac risk should not rely on these conventional parameters. Thus, the use of MRI for assessing myocardial iron should be adopted in the routine clinical management of patients with beta-thalassemia major.

Oral Cavity Cancer

The oral cavity is anterioly located and unique in the variety of tissues contained in this area. Although oral cancer screening may be done on clinical examination, imaging plays a critical role in staging and determination of deep margins for either tumor resectability or radiation planning. This article discusses the relevant anatomy on magnetic resonance imaging (MRI), including the lips and gingiva, floor of mouth, and oral tongue. This is followed by a discussion of standard MRI techniques, American Joint Committee on Cancer (AJCC) classification, and relevant MRI findings with discussion and imaging examples of carcinoma in major sites, including floor of mouth, oral tongue, buccal mucosa, bony upper alveolus, hard palate, and retromolar trigone. A brief summary of newer imaging techniques for evaluation of oral cancer is also presented.

Detection of Posttraumatic Cartilage Injury Using Quantitative T1rho Magnetic Resonance Imaging

Cartilage injuries following trauma are a common problem and can lead to premature, secondary osteoarthritis. Standard magnetic resonance imaging techniques can detect cartilage breakdown associated with morphological changes, such as decreases in cartilage thickness and volume, but it cannot detect early changes of the cartilage matrix. There is a need for a noninvasive method with which to diagnose articular cartilage abnormalities at early stages in order to initiate early treatment prior to the macroadaptive changes seen on radiographs. Early events in the development of cartilage breakdown include the loss of proteoglycans, changes in water content, and molecular-level changes in collagen1,2. Early diagnosis of cartilage injury requires the ability to detect changes in proteoglycan concentration and collagen integrity noninvasively before gross morphological changes occur. Standard cartilage-dedicated magnetic resonance imaging techniques such as T2-weighted, proton-density-weighted fast-spin-echo sequences and spoiled gradient-echo sequences are inconclusive in quantifying early degenerative changes, especially biochemical changes such as proteoglycan loss3. It appears that T1rho-weighted imaging can provide quantitative measures of pathologic cartilage matrix changes. Previous studies have demonstrated significant differences in T1rho relaxation times when patients with symptomatic osteoarthritis have been compared with normal controls4. In the present study, we describe two cases in which cartilage injuries were not detected with standard morphological magnetic resonance imaging but in which T1rho-weighted imaging was able to detect cartilage abnormalities in vivo that were confirmed at the time of arthroscopy. The patients were informed that data concerning these cases would be submitted for publication. Case 1. A forty-five-year-old man presented with a three-week history of pain in the right knee following a motor-vehicle accident. Clinical examination demonstrated a moderate intra-articular knee effusion, a positive grade-2 Lachman test, and a positive pivot-shift test. The patient also had mild discomfort on the McMurray …

The Use of Magnetic Resonance Arthrography to Detect Partial-Thickness Rotator Cuff Tears

P artial-thickness rotator cuff tears can be caused by trauma or anatomic impingement, or they can be a natural consequence of aging. They may involve either the articular surface, the bursal surface, or both sides of the rotator cuff. They can be asymptomatic or a potential source of shoulder dysfunction. Recent studies have seemed to indicate that partial-thickness cuff tears can progress and do not heal on their own1. The articular side of the rotator cuff is hypovascular (Fig. 1), and the collagen bundles on the articular side are thinner and less uniform (Fig. 2), making articular-sided partial-thickness rotator cuff tears two to three times more common than bursal-sided tears2-8. Magnetic resonance imaging, although a useful and established technique for detecting full-thickness rotator cuff tears, has been found to be less reliable in detecting partial-thickness tears. With the use of standard magnetic resonance imaging techniques, many partial-thickness rotator cuff tears are missed9-12. In 1992, Traughber and Goodwin reported a sensitivity ranging from 56% to 72% and a specificity ranging from 83% to 85% for arthroscopically proven partial-thickness rotator cuff tears9. However, in another study, an 83% rate of false-negative results was reported for arthroscopically proven partial-thickness tears10. Wright and Cofield found only six definite partial-thickness tears on preoperative magnetic resonance imaging studies in eighteen patients with arthroscopically proven partial-thickness tears11. Fig. 1 Coronal photomicrograph of the zone of diminished vascularity of the supraspinatus tendon. The arrow points to the critical zone of hypovascularity of the articular side of the tendon. Magnetic resonance arthrography may improve the sensitivity in the detection of partial-thickness rotator cuff tears. Two years ago, we began a prospective study to detect partial-thickness articular-sided rotator cuff tears using an intra-articular injection of gadolinium …