Emerging dominance of summer rainfall driving High Arctic terrestrial-aquatic connectivity.

Hydrological transformations induced by climate warming are causing Arctic annual fluvial energy to shift from skewed (snowmelt-dominated) to multimodal (snowmelt- and rainfall-dominated) distributions. We integrated decade-long hydrometeorological and biogeochemical data from the High Arctic to show that shifts in the timing and magnitude of annual discharge patterns and stream power budgets are causing Arctic material transfer regimes to undergo fundamental changes. Increased late summer rainfall enhanced terrestrial-aquatic connectivity for dissolved and particulate material fluxes. Permafrost disturbances (<3% of the watersheds' areal extent) reduced watershed-scale dissolved organic carbon export, offsetting concurrent increased export in undisturbed watersheds. To overcome the watersheds' buffering capacity for transferring particulate material (30 ± 9 Watt), rainfall events had to increase by an order of magnitude, indicating the landscape is primed for accelerated geomorphological change when future rainfall magnitudes and consequent pluvial responses exceed the current buffering capacity of the terrestrial-aquatic continuum.

Differential impact of thermal and physical permafrost disturbances on High Arctic dissolved and particulate fluvial fluxes.

Climate warming and changing precipitation patterns have thermally (active layer deepening) and physically (permafrost-thaw related mass movements) disturbed permafrost-underlain watersheds across much of the Arctic, increasing the transfer of dissolved and particulate material from terrestrial to aquatic ecosystems. We examined the multiyear (2006-2017) impact of thermal and physical permafrost disturbances on all of the major components of fluvial flux. Thermal disturbances increased the flux of dissolved organic carbon (DOC), but localized physical disturbances decreased multiyear DOC flux. Physical disturbances increased major ion and suspended sediment flux, which remained elevated a decade after disturbance, and changed carbon export from a DOC to a particulate organic carbon (POC) dominated system. As the magnitude and frequency of physical permafrost disturbance intensifies in response to Arctic climate change, disturbances will become an increasingly important mechanism to deliver POC from terrestrial to aquatic ecosystems. Although nival runoff remained the primary hydrological driver, the importance of pluvial runoff as driver of fluvial flux increased following both thermal and physical permafrost disturbance. We conclude the transition from a nival-dominated fluvial regime to a regime where rainfall runoff is proportionately more important will be a likely tipping point to accelerated High Arctic change.

Chloride inputs to the North Saskatchewan River watershed: the role of road salts as a potential driver of salinization downstream of North America's northern most major city (Edmonton, Canada).

Multiple anthropogenic activities are driving the salinization of freshwater environments threatening water resources worldwide. Accordingly, this research will first examine the spatial and temporal variability of major ions (i.e. Ca2+, Mg2+, Na+, K+, SO42-, CO32-, and HCO3-) upstream and downstream of the northernmost major city in North America (Edmonton, Canada). Second, this research will estimate the relative contributions of the major sources of chloride (Cl), the main constituent of road deicers, to the sub-basin around Edmonton. Monthly water quality data was for three sites on the North Saskatchewan River (NSR): Rocky Mountain House (RMH - downstream of the Rocky Mountain headwaters), Devon Bridge (upstream of Edmonton) and Pakan Bridge (downstream of Edmonton). Change ratios investigate the downstream alterations of major ions at Pakan and Devon, relative to RMH. Seasonal Kendall tests examine temporal trends (1987-2017). A mass-balance approach then quantifies the major sources of Cl in the sub-basin of the NSR between Devon and Pakan. Progressing from the Rocky Mountain headwaters (at RMH) to downstream of Edmonton (at Pakan), Cl- increased by >5.5 times, Na+ by 4.8 times and K by 2.7 times. No significant temporal trends for Cl-, Na+ and K+ were evident at Devon (upstream of Edmonton), whereas all three significantly increased at Pakan (downstream of Edmonton). Deicers (54%), agriculture (20%), along with waste water treatment plant and industrial effluent (15%) were the largest Cl sources in the NSR Devon-Pakan sub-basin. In total, 77 Gg yr-1 of Cl (or 6 t km2 yr-1) is added to the Devon-Pakan sub-basin, of which, 43 Gg yr-1 is retained. Understanding and managing the major drivers of freshwater salinization will be of increasing importance in the 21st century owing to the potential salinization of freshwater resources in the context of a changing climate.

Landscape-scale genetic variation in a forest outbreak species, the mountain pine beetle (Dendroctonus ponderosae).

The mountain pine beetle Dendroctonus ponderosae is a native species currently experiencing large-scale outbreaks in western North American pine forests. We sought to describe the pattern of genetic variation across the range of this species, to determine whether there were detectable genetic differences between D. ponderosae occupying different host trees in common localities, and to determine whether there was molecular evidence for a past demographic expansion. Using a combination of amplified fragment length polymorphism (AFLP) and mitochondrial sequencing analyses, we found evidence of genetic structuring among populations that followed a broad isolation-by-distance pattern. Our results suggest that the geographical pattern of gene flow follows the core distribution of the principal D. ponderosae host species, around rather than across the Great Basin and Mojave Deserts. Patterns of haplotype diversity and divergence were consistent with a range-wide population expansion. This signal was particularly pronounced in the northern part of the species' range, where outbreak activity is currently increasing. Using AFLP markers, we were unable to detect significant differences among groups of insects sampled from different host trees in common locations. Incidentally, we found that a large proportion of the polymorphic AFLP markers were gender-specific, occurring only in males. While we did not include these markers in our analyses, this finding warrants further investigation.

Angled oblique sagittal MR imaging of rotator cuff tears: comparison with standard oblique sagittal images.

OBJECTIVE: To compare the accuracy for diagnosing rotator cuff tears of oblique coronal images supplemented with standard oblique sagittal images versus thinner-section angled oblique sagittal images. DESIGN AND PATIENTS: The study included 75 consecutive patients who had a shoulder MR scan followed by arthroscopy. MR images included oblique coronal, oblique sagittal (4 mm thick, 1 mm interslice gap), and angled oblique sagittal (3 mm/0.2 mm) images perpendicular to the lateral cuff. A musculoskeletal staff radiologist and fellow separately evaluated the cuff for tears on the oblique coronal images supplemented with either the oblique sagittal or the angled sagittal images. RESULTS: For distinguishing a cuff tear from no tear, the staff radiologist had an accuracy of 0.76 (95% confidence interval: 0.67, 0.85) with the standard sagittal set, and 0.88 (0.80, 0.95) with the angled set (P=0.04). There was a nonsignificant improvement in accuracy for the fellow, calculated as 0.73 (0.63, 0.83) on the standard sagittal set and 0.76 (0.67, 0.85) on the angled set. Both readers also improved their diagnostic accuracy for partial-thickness tears with the angled set, although the improvement was statistically significant only for the staff radiologist. CONCLUSION: There is a slight improvement in accuracy for diagnosing rotator cuff tears, particularly partial-thickness tears, for the more experienced radiologist using thinner-section angled oblique sagittal images. These images may be useful as a supplemental sequence in patients where it is important to identify partial-thickness tears accurately.

Superior labrum anterior-posterior (SLAP) tears: evaluation of three MR signs on T2-weighted images.

PURPOSE: To compare the sensitivity and specificity of three magnetic resonance (MR) imaging signs for the diagnosis of superior labrum anterior-posterior (SLAP) tears. MATERIALS AND METHODS: The study involved 23 consecutive patients with a type 2, 3, or 4 SLAP tear at arthroscopy and 31 age-matched control patients with an arthroscopically normal or type 1 SLAP lesion. The superior labrum was evaluated on MR images for high signal intensity extending to the articular surface in the posterior third of the labrum, an irregular or laterally curved area of high signal intensity, or two high-signal-intensity lines. RESULTS: The sensitivity, specificity, and accuracy of posterior high signal intensity for a type 2, 3, or 4 SLAP tear were 48%, 94%, and 74%, respectively, for observer 1 and 61%, 81%, and 72%, respectively, for observer 2. For laterally curved area of high signal intensity, these values were 65%, 84%, and 76%, respectively, and 56%, 84%, and 72%, respectively. For two high-signal-intensity lines, these values were 17%, 94%, and 61%, respectively, and 13%, 94%, and 59%, respectively. For the presence of either posterior or laterally curved high signal intensity, the sensitivity was 65% for both observers, whereas the specificity was 84% for observer 1 and 74% for observer 2. The kappa values for interobserver agreement were 0.60 for posterior high signal intensity and 0.58 for laterally curved high signal intensity. CONCLUSION: Laterally curved and posterior high signal intensities are specific signs for distinguishing a SLAP tear from a normal-variant superior sublabral recess.

The biologic response to laser thermal modification in an in vivo sheep model.

The purpose of this study was to evaluate the effect of nonablative laser energy on mechanical, histologic, ultrastructural, and biochemical properties of joint capsular tissue in an in vivo sheep model. Femoropatellar joint capsule was treated with the holmium:yttrium-aluminum-garnet laser via an arthroscope, and tissues were harvested immediately after surgery, or at 3, 7, 14, 30, 60, 90, and 180 days after surgery (n = 8/group). Laser treatment caused significant decreases in tissue stiffness from 0 to 7 days after surgery, then stiffness gradually increased after 14 days. Tissue strength was lowest 3 days after laser treatment. Histologic examination revealed immediate collagen hyalinization and cell necrosis, followed by active cellular response characterized by extensive fibroblast migration and capillary sprouting. Tissue appeared to be normal histologically 60 days after surgery; however, collagen fibrils remained uniformly small. This study showed an active tissue response secondary to thermal modification with concomitant recovery of mechanical properties by 30 days after surgery. Whether the shrinkage or joint stability was maintained with time remains to be evaluated. To clarify the advantages and disadvantages of this technique, a carefully controlled clinical trial with long term followup should be performed.

Fat-suppressed fast spin-echo mid-TE (TE[effective]=34) MR images: comparison with fast spin-echo T2-weighted images for the diagnosis of tears and anatomic variants of the glenoid labrum.

OBJECTIVE: To compare the sensitivity, specificity, and accuracy of fat-suppressed fast spin-echo (FSE) mid-TE (TE[effective]=34) images with fat-suppressed FSE T2-weighted images for the diagnosis of labral abnormalities. DESIGN AND PATIENTS: The study included 27 consecutive patients who had axial fat-suppressed FSE T2-weighted and fat-suppressed FSE mid-TE MR images, and had labral abnormalities diagnosed at arthroscopy. The acquisition time was about 5 min for each sequence, but the mid-TE sequence allowed a higher spatial resolution than the T2-weighted images (256x256 versus 256x192). Twenty-eight age-matched patients with arthroscopically normal labra were included as a control group. The labrum was graded on the MR images as normal or abnormal separately by two musculoskeletal radiologists who were masked to the history and arthroscopic results. The surgical findings were used as the gold standard for calculating the sensitivity, specificity, and accuracy for interpreting the correct location of a labral abnormality. The sensitivity, specificity, and accuracy for the two sequences were compared with a McNemar test, and significance defined as P<0.05. RESULTS: For observer 1, the sensitivity for labral abnormalities was 0.59 on the T2-weighted images, and 0.78 on the mid-TE images (P=0.12). The specificity was 0.54 for the T2-weighted, and 0.64 for the mid-TE images (P=0.51). The accuracy was 0.56 for the T2-weighted, and 0.71 for the mid- TE images (P=0.08). For observer 2, the sensitivity/specificity/accuracy was 0.67/0.93/0.80 for the T2-weighted, and 0.70/0.86/0.78 for the mid-TE images (all P>0.5). CONCLUSION: In this small study there is no statistically significant difference for demonstrating labral abnormalities between FSE T2-weighted images, and higher-resolution fat-suppressed FSE mid-TE (TE[effective]=34) images obtained with a similar acquisition time. Although there was a general trend toward higher sensitivity and accuracy with the mid-TE sequence, particularly for one of the two observers, a larger study is needed to determine whether this is the preferred single axial pulse sequence for conventional MR imaging of the labrum.

Injuries in collegiate wrestling.

We evaluated the data of the National Collegiate Athletic Association Injury Surveillance System on collegiate wrestling with a focus on musculoskeletal injuries. Over 800,000 athlete-exposures during an 11-year period compose these data. Findings particular to wrestling and a comparison with other collegiate sports are included. Collegiate wrestling had a relatively high rate of injury at 9.6 injuries per 1000 athlete-exposures. It was second to spring football in total injury rate. Most injuries in this study were not serious, with 6.3% resulting in surgery and 37.6% resulting in a week or more off from wrestling. There was only one catastrophic, nonfatal injury. The knee, shoulder, and ankle were the most commonly injured regions, and injuries to them were often the more serious. Sprains, strains, and contusions were the most common injury types. Takedowns and sparring were the most common activities at the time of injury. Mechanism of injury was evaluated; rotation about a planted foot and contact with environmental objects were identified as areas needing further attention. Illegal action accounted for only 4.6% of injuries in competition. Competition had a significantly higher injury rate than practice, but the injury profiles of these two areas showed both to be equally important. The preseason and regular season had higher injury rates than the postseason, but, again, the injury profiles of these periods were similar. Injury percentages were similar among the 10 weight classes.

Anterior versus posterior, and rim-rent rotator cuff tears: prevalence and MR sensitivity.

PURPOSE: To determine the relative distribution of the locations of rotator cuff tears, and the sensitivity of anterior versus posterior tears on MR images. PATIENTS AND METHODS: We identified 110 consecutive patients who had a shoulder MR and either a partial-thickness or a small full-thickness rotator cuff tear diagnosed at arthroscopy. From the arthroscopy videotapes, we classified the tears as centered in the anterior or posterior half of the cuff, and as either in the critical zone or adjacent to the bony insertion. The original MR interpretation was compared with the arthroscopic findings. MR sensitivity and patient age were compared between patients with tears in the anterior and posterior halves of the cuff. In addition, in patients with partial tears less than 2 cm in diameter, an age comparison between those with tears in the critical zone and those with articular surface tears adjacent to the bony insertion (rim-rent tear) was performed. RESULTS: The tear was centered in the anterior half of the rotator cuff in 79% of the patients younger than 36 years old, and in 89% of the patients 36 years old and over. The average age of the patients with tears in the anterior half (44 years) was not significantly different from the average age of those with posterior tears (40 years) (P = 0.23). The sensitivity of MR for anterior tears was 0.69, and for posterior tears it was 0.56 (P = 0.17). The average age of the 9 patients with rim-rent tears was 31 years, while that of the 28 patients with similarly-sized partial tears not involving the insertion was 40 years old (P = 0.048). Five of the nine rim-rent tears (0.56) were interpreted correctly on the original MR report; two of the other tears were misinterpreted as intratendinous fluid but were diagnosable in retrospect. CONCLUSION: Even in patients less than 36 years old, most partial and small full-thickness rotator cuff tears are centered in the anterior half of the supraspinatus. Although our figure for MR sensitivity for these tears is lower than in recent articles, we found no significant difference between the sensitivity of MR for diagnosing posterior tears versus tears in the anterior half of the supraspinatus tendon. Rim-rent tears can be mistaken for intratendinous signal, and should be carefully looked for in younger patients with shoulder pain.

Rotator cuff tendinopathy and subacromial impingement syndrome.

Subacromial impingement syndrome is one of the most frequently seen causes of shoulder pain. The symptoms are often vague and may be difficult to differentiate from other shoulder problems. The purpose of this paper is to provide the clinician with a more thorough understanding of this entity by reviewing the pertinent anatomy and underlying etiology. Suggestions are made to aid in establishing the diagnosis, and treatment recommendations are proposed.

MR imaging of rotator cuff tendon tears: comparison of T2*-weighted gradient-echo and conventional dual-echo sequences.

OBJECTIVE: Although MR imaging evaluation of the rotator cuff is usually done with proton density- and T2-weighted spin-echo techniques, interest also exists in T2*-weighted gradient-recalled echo techniques. The shorter scan times of T2*-weighted sequences can be used to increase the number of signal averages and thus improve the signal-to-noise ratio. Our purpose in this study was to compare the sensitivity and specificity of oblique coronal T2*-weighted MR image interpretations with conventional dual-echo T2-weighted MR image interpretations when diagnosing rotator cuff tears. SUBJECTS AND METHODS: Forty-seven consecutive patients who underwent both MR imaging and shoulder arthroscopy were included in this study. The MR examination included both a 7 min 20 sec acquisition time proton density- and T2-weighted oblique coronal sequence and a 7 min 5 sec T2*-weighted oblique coronal sequence. The oblique coronal dual-echo T2-weighted images were evaluated by two of the authors independently, who were unaware of the arthroscopic findings. Each of the two observers graded each cuff as being intact, having a partial-thickness tear, or having a full-thickness tear. After a 3-week interval, each of the two observers then interpreted the T2*-weighted oblique coronal MR images in the same manner. Sensitivity and specificity for the two sets of interpretations were calculated in terms of the ability of the observers to use the two sequences to distinguish an intact cuff from a rotator cuff tear and to distinguish a partial-thickness cuff tear from an intact cuff or full-thickness tear. The results were then compared using Student's t test calculations. RESULTS: For distinguishing an intact cuff from a torn cuff, the sensitivity of the observers' interpretations was lower for the T2*-weighted images than for the conventional dual-echo T2-weighted images. The specificity also decreased with interpretation of the T2*-weighted images for one observer and was unchanged for the second observer. For distinguishing a partial-thickness cuff tear from a non-partial-thickness cuff tear (intact or full-thickness tear), the sensitivity and specificity of both observers decreased with interpretations of the T2*-weighted images when compared with the conventional dual-echo T2-weighted images. The results did not reach statistical significance. CONCLUSION: In this small study evaluating the ability of observers to diagnose rotator cuff tears on oblique coronal MR images only, interpretations of T2*-weighted images tended to be less sensitive and specific than interpretations of standard dual-echo T2-weighted images.

Anteroinferior tears of the glenoid labrum: fat-suppressed fast spin-echo T2 versus gradient-recalled echo MR images.

OBJECTIVE: To compare fat-suppressed fast spin-echo (FSE) T2-weighted images with gradient-recalled echo (GRE) T2*-weighted images in the evaluation of anteroinferior labral tears. DESIGN: MR images were retrospectively reviewed by two radiologists masked to the history and arthroscopic findings. They separately interpreted the anteroinferior labrum as torn or intact, first on one pulse sequence and then, 4 weeks later, on the other sequence. The MR interpretations were correlated with the arthroscopic findings. PATIENTS: Nine patients with anteroinferior labral tears, and nine similarly-aged patients with normal, labra were studied. RESULTS AND CONCLUSIONS: Observer 1 had a sensitivity of 0.56 on the GRE images and 0.67 on the FSE images (P > 0.5), with a specificity of 1.0 for both sequences. Observer 2 had a sensitivity of 0.78 and a specificity of 0.89 for both sequences. In this small study there is no significant difference between GRE and fat-suppressed FSE images in their ability to diagnose anteroinferior labral tears. When evaluating the labrum with conventional MRI, axial fat-suppressed FSE T2-weighted images can be used in place of GRE images without a loss of accuracy.

The effect of thermal heating on the length and histologic properties of the glenohumeral joint capsule.

The purpose of this study was to evaluate the effect of temperature on shrinkage and the histologic properties of glenohumeral joint capsular tissue. Six fresh-frozen cadaveric shoulders were used for this study. Seven joint capsule specimens were taken from different regions from each glenohumeral joint and assigned to one of seven treatment groups (37 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees C) using a randomized block design. Specimens were placed in a tissue bath heated to one of the designated temperatures for 10 minutes. Specimens treated with temperatures at or above 65 degrees C experienced significant shrinkage compared with those treated with a 37 degrees C bath. The posttreatment lengths in the 70 degrees, 75 degrees, and 80 degrees C groups were significantly less than the pretreatment lengths. Histologic analysis revealed significant thermal alteration characterized by hyalinization of collagen in the 65 degrees, 70 degrees, 75 degrees, and 80 degrees C groups. This study demonstrated that temperatures at or above 65 degrees C caused significant shrinkage of glenohumeral joint capsular tissue. These results are consistent with histologic findings, which revealed significant thermal changes of collagen in the 65 degrees, 70 degrees, 75 degrees, and 80 degrees C groups. To verify the validity of laser application for shrinkage of joint capsule, studies designed to compare these findings with the effects of laser energy must be performed.

Evaluation of post-exercise magnetic resonance images of the rotator cuff.

OBJECTIVE: To examine the effect of strenuous exercise on the magnetic resonance imaging (MRI) characteristics of the rotator cuff tendon. A second objective was to define an optimal time to image the rotator cuff and possibly eliminate exercise-induced false positives. DESIGN AND PATIENTS: Five male subjects from 24 to 38 years old with normal rotator cuffs by history, physical examination, and screening MRI underwent a rotator cuff exercise session on the Biodex System 2 (Biodex, Shirley, New York). The exercise sessions were followed by sequential MRI scans of the exercised shoulder. These were performed immediately and at 8 h and 24 h after exercise. RESULTS AND CONCLUSIONS: The rotator cuff tendon and subacromial-subdeltoid bursal signal remained unchanged from the pre-exercise through the 24-h post-exercise scans. The rotator cuff muscle signal was increased in five of five subjects on the immediate post-exercise fat-suppressed T2-weighted images. This signal returned to baseline by the 8-h scan. Positive findings of rotator cuff pathology on MRI after strenuous athletic activity should not be discounted as normal exercise-induced changes. Also, diagnostic MRI scanning may take place after a practice session without an increased risk of false positives.

The effect of tourniquet use on postoperative strength recovery after arthroscopic meniscectomy.

The purpose of this prospective study was to determine the effect of pneumatic tourniquet use during arthroscopic meniscectomy on postoperative recovery of quadriceps and hamstring strength. Thirty-four patients with no ligamentous instability underwent arthroscopic meniscectomy after random assignment to the tourniquet or no tourniquet group. Tourniquet pressure was determined with a nomogram that considered thigh circumference and systolic blood pressure at time of induction. Quadriceps and hamstring strengths were tested preoperatively and at 1 week and 4 weeks postoperatively on a Biodex isokinetic dynamometer and expressed as a percentage of the uninvolved side. No significant differences in quadriceps or hamstring strength were noted between groups at any time periods. The findings of this study indicate that recovery of quadriceps and hamstring strength after arthroscopic meniscectomy is not adversely affected by tourniquet use if tourniquet times and pressures are carefully controlled.

Anterosuperior labral variants of the shoulder: appearance on gradient-recalled-echo and fast spin-echo MR images.

PURPOSE: To characterize the magnetic resonance (MR) imaging appearance of two anterosuperior labral variants, the sublabral foramen (SLF) and the Buford complex. MATERIALS AND METHODS: The axial gradient-recalled-echo (GRE) MR images and the fat-suppressed, T2-weighted, fast spin-echo (SE) images were reviewed in 19 patients with arthroscopically proved SLF and 11 patients with a Buford complex. The anterosuperior labrum was graded as normal, detached, or absent on the images. RESULTS: For the patients with an SLF, the anterosuperior labrum was graded as detached in all patients who underwent fast SE imaging but in only 43% of patients who underwent GRE imaging. For the patients with a Buford complex, the anterosuperior labrum was graded as absent in only 30% of patients who underwent GRE imaging and in none of the patients who underwent fast SE imaging. CONCLUSION: Isolated MR abnormalities of the anterosuperior labrum may represent either of the two asymptomatic labral variants.

Open inferior glenohumeral dislocation.

An open inferior glenohumeral dislocation or luxatio erecta humeri is a rare type of shoulder dislocation, with only two cases reported in the literature. Presented is the case of a 36-year-old farmer who sustained an open inferior glenohumeral dislocation in a farm equipment accident. The humeral head penetrated the skin inferior to the pectoralis major muscle, an avulsion fracture of the greater tuberosity was present, and the subscapular tendon was ruptured near its insertion into the lesser tuberosity. At follow-up 18 months after injury, the restricted range of motion of the shoulder remained despite treatment attempts, including manipulation under anesthesia with arthroscopic debridement of the shoulder; however, no evidence of avascular necrosis of the humeral head was found.

Suprascapular nerve entrapment by ganglion cysts: a report of six cases with arthroscopic findings and review of the literature.

Suprascapular nerve entrapment by a ganglion cyst can produce pain and shoulder dysfunction. We report six cases with the associated arthroscopic intraarticular findings of a posterior capsulolabral injury (only the second such description) and review the literature. Based on the current literature and our experience, we document our treatment algorithm for suprascapular nerve entrapment secondary to a ganglion cyst. We believe it is necessary to evaluate and treat the intraarticular pathology as well as the ganglion cyst/nerve entrapment to successfully manage these patients.

Effect of field of view on MR diagnosis of rotator cuff tears.

PURPOSE: To determine the effect of decreasing the field of view (FOV) on the accuracy of MR for diagnosing rotator cuff tears. MATERIAL AND METHODS: One hundred shoulder MR scans with surgical correlation were evaluated for the presence or absence of a cuff tear. The sensitivity and specificity of MR relative to the surgical results were determined for the 59 patients scanned with a 24-cm FOV, and the 41 patients scanned with an 18-cm FOV. All other imaging parameters including acquisition time were identical. The sensitivity and specificity of the two groups were compared using a t-test. RESULTS: The specificity of MR for diagnosing a rotator cuff tear improved from 0.65 for the 24-cm FOV group to 0.89 for the 18-cm FOV group (P = 0.04). The sensitivity changed from 0.91 to 0.96 (P = 0.25). CONCLUSION: Reducing the FOV from 24 cm to 18 cm results in a statistically significant improvement in specificity of MR for diagnosing rotator cuff tears.