Isolated pelvic fluid in males on outpatient magnetic resonance imaging examinations: differences in incidence based on age.

PURPOSE: Determine the incidence and amount of isolated pelvic fluid in males, stratified by age, on outpatient pelvic magnetic resonance imaging (MRI) examinations performed for lower back or extremity pain. METHODS: After institutional review board approval, 161 pelvic MRIs performed on males for musculoskeletal or neurologic indications over an 18-month period were retrospectively reviewed for isolated pelvic fluid by 2 radiologists. Patients with a potential etiology for the fluid were excluded. Volume and maximal 2-dimensional measurements of fluid were calculated. Statistical analysis included logistic regression, Wilcoxon rank-sum, and χ tests. RESULTS: Twenty (44.4%) of 45 patients 5 to 29 years old, 5 (10%) of 50 patients 30 to 49 years old, and 4 (6.1%) of 66 patients older than 50 years had isolated pelvic fluid (P < 0.001). Mean volume of fluid was 2.5 mL; 97% (28/29) had less than 10 mL. Mean maximal 2-dimensional measurement was 2.1 cm; 93% (27/29) had less than 6 cm(2). CONCLUSIONS: Isolated fluid is greater than 7 times more common on outpatient pelvic MRIs in males younger than 30 years compared with men older than 49 years. Fluid rarely exceeded 10 mL or 6 cm(2).

Prevalence of malignancy in thyroid nodules with an initial nondiagnostic result after ultrasound guided fine needle aspiration.

The objective of this study was to determine the rate of malignancy in thyroid nodules with an initial nondiagnostic fine needle aspiration. From October 2001 to April 2007, biopsies were performed on 1344 thyroid nodules in our practice. Biopsies were performed on nodules using 25-27 gauge needles, ultrasound guidance and multiple passes using both suction and capillary action. We retrospectively reviewed the results of these biopsies as well as any further management of nodules that received nondiagnostic results (IRB HUM00006459). Following initial biopsy, 295/1344 (21.9%) of nodules received nondiagnostic pathologic results. Of this population, 39 nodules (13.1%) were lost to follow-up. Of the remaining 256 nodules that received a repeat FNA, surgical excision, or greater than 24 months of clinical and imaging follow-up, only five cancers were detected, representing only 2% of the population that received an initial nondiagnostic biopsy result. All of these cancers were papillary neoplasms. When rigorous, ultrasound-guided, fine needle aspiration of thyroid nodules is performed, a nondiagnostic histopathologic result should not be interpreted as suspicious for thyroid cancer. Given the low rate of malignancy in this population (2%), we suggest that clinical and imaging follow-up of these nodules, opposed to repeat sampling, is warranted.

Contrast-enhanced magnetic resonance imaging positively impacts the management of some patients with rheumatoid arthritis or suspected RA.

OBJECTIVE: Early diagnosis of rheumatoid arthritis (RA) is important given the availability of highly effective disease-modifying antirheumatic (DMARD) medications, including biologics. However, because of associated risks and cost, accurately assessing disease activity is critical. Because magnetic resonance imaging (MRI) can detect synovitis and bone marrow edema, both of which may precede erosion development, we sought to determine the impact of enhanced MRI on patient management in a group of patients referred for MRI by rheumatologists. MATERIALS AND METHODS: After institutional review board approval, we evaluated all hand MRI examinations referred by the rheumatology department for synovitis evaluation between September 2007 and May 2009. The magnetic resonance images were classified as positive or negative and later reviewed by 2 musculoskeletal radiologists. A musculoskeletal radiologist and rheumatologist jointly reviewed the patients' medical records to determine the following: (1) Did the MRI findings alter treatment? (2) Were the treatment alterations beneficial? RESULTS: The study included 48 patients (39 women and 9 men) with a mean age of 51 years (range, 18-79 years). Significant management changes initially occurred in 79% (23/29) of the positive (DMARDs added in 20) and in 11% (2/19) of the negative MR examinations with average follow-up of ~300 days. Eighty percent (16/20) of the patients with DMARDs added experienced symptom improvement, none of the patients whose medications were discontinued experienced symptom relapse, and 18% (4/22) of patients without initial therapeutic changes required delayed treatment modifications. CONCLUSIONS: Enhanced MRI significantly altered clinical management in 50% of these patients with RA or suspected RA. Therefore, when the clinical picture in a patient with RA or suspected RA is unclear, enhanced MRI can provide useful guidance for treatment modifications.

The cartilage black line sign: an unexpected MRI appearance of deep cartilage fissuring in three patients.

Many patterns of cartilage signal anomalies have been described in the knee since the advent of magnetic resonance imaging (MRI). With the now widespread use of preoperative MRI, some of these anomalies have proven to represent true pathology, while others have been shown to be normal variants or artifacts at arthroscopy. We describe three patients with an MR cartilage abnormality, not previously illustrated in the literature, consisting of a thin dark signal line on T2-weighted imaging, oriented perpendicular to the plane of imaging. This aberration proved to represent a deep cartilage cleft at arthroscopy (two patients) and at CT arthrography (one patient). Such full thickness fissures are generally considered to have the opposite appearance, that of fluid signal intensity on T2-weighted images.

Excretory urography: trends in clinical use and diagnostic yield.

OBJECTIVE: To assess for changes in clinical usage and diagnostic yield of excretory urography (EU) following the introduction of CT urography (CTU). MATERIALS AND METHODS: We retrospectively reviewed reports from 6313 EUs performed between July 1995 and February 2006. The specialty of the ordering physician and clinical indication for the study were recorded, as were any collecting system, ureter, or bladder abnormalities suspicious for urothelial malignancy identified on EU. The proportion of EUs ordered for each indication and the positivity rate for each finding were compared prior to and after 2000, when CTU was introduced. RESULTS: Demand for EU by all physicians has decreased threefold. Since 2000, there has been a decrease in the proportion of EUs performed for all indications: obstruction (P < 0.0001), stones (P < 0.0001), urothelial malignancy (P < 0.0001), pain (P < 0.0001), post-operative (P < 0.0001), trauma (P < 0.03), hematuria (P < 0.0001), and urinary tract infection (P < 0.0001). Proportional demand by urologists has not changed significantly (P = 0.105). For exams ordered by urologists, the positivity rate for intraluminal defects within the collecting system and bladder has decreased (P < 0.0001). For exams ordered by non-urologists, there has been no significant change in the positivity rate of urinary tract filling defects (P > 0.05). CONCLUSION: The number of excretory urograms has decreased dramatically, although the proportion of these studies ordered by urologists is unchanged. The positivity rate of EU findings suggesting urothelial malignancy in the collecting system and bladder has decreased, likely because, with the advent of CTU, urologists have changed their ordering patterns for some clinical indications.

Giant tumefactive perivascular spaces.

We describe the imaging characteristics of giant tumefactive perivascular spaces in a 37-year-old man who initially presented at the age of twenty years with vision change and headache and was found to have probable low grade neoplasm. The patient was followed subsequently at 8 years and 17 years later at our institution with stable imaging and neurologic exam. Magnetic resonance imaging demonstrated multiple cystic mass in the right frontal lobe which was stable in size and appearance. The mass followed signal intensity identical to cerebrospinal fluid on all sequences and was consistent with a giant tumefactive perivascular space. This report illustrates the need to keep this entity in mind when imaging evaluation demonstrates a lesion isointense to cerebrospinal fluid on all sequences. These lesions can actually be quite large and ominous appearing and many proceed to biopsy unnecessarily.