Safety and image quality of MR-conditional external fixators for 1.5 Tesla extremity MR.

PURPOSE: To evaluate the safety and image quality of extremity MR examinations performed with two MR conditional external fixators located in the MR bore. MATERIALS AND METHODS: Single-center retrospective study of a prospectively maintained imaging dataset that evaluated MR examinations of extremities in patients managed with external fixations instrumentation and imaged on a single 1.5T MR scanner. The fixation device was one of two MR-conditional instrumentation systems: DuPuy Synthes (aluminum, stainless steel, carbonium and Kevlar) or Dolphix temporary fixation system (PEEK-CA30). Safety events were recorded by the performing MR radiologic technologist. A study musculoskeletal radiologist assessed all sequences to evaluate for image quality, signal- and contrast-to-noise ratios (SNR/CNR), and injury patterns/findings. RESULTS: In the 13 men and 9 women with a mean age of 42 years (range 18 to 72 years), most patients (19/22 patients; 86%) were involved with trauma resulting in extremity injury requiring external fixation. MR examinations included 19 knee, 2 ankle, and 1 elbow examinations. There were no adverse safety events, heating that caused patient discomfort, fixation dislodgement/perturbment, or early termination of MR examinations. All examinations were of diagnostic quality. Fat-suppressed proton density sequences had significantly higher SNR and CNR compared to STIR (p = 0.01 to 0.04). The lower SNR of STIR and increased quality of fat-suppressed proton density during the study period led to the STIR sequence being dropped in standard MR protocol. CONCLUSION: MR of the extremity using the two study MR conditional external fixators within the MR bore is safe and feasible.

Focal Segmental Glomerulosclerosis Preceding Type 2 Papillary Renal Cell Carcinoma.

Renal cell carcinoma (RCC) is the predominant renal malignancy in adults. Of the four general subtypes, papillary renal cell carcinoma (P-RCC) is the second most common and can be subdivided into type I, type II, and a mixture of type I and II. Focal segmental glomerulosclerosis (FSGS) is the most common glomerulopathy at all ages, and it can be seen as a paraneoplastic syndrome. RCC, in general, is known to present with many paraneoplastic syndromes, and glomerulopathies are among these. Rarely, RCC and glomerulopathies may overlap in the same patient. Here, we report a 58-year-old male with a past medical history of FSGS and chronic kidney disease (CKD), stage III, who was found to have an incidental renal mass that was later diagnosed as type II P-RCC. The histology showed pseudostratified tumor cells with an eosinophilic cytoplasm that formed papillary configurations and displayed areas of necrosis. The prior FSGS diagnosis exhibited segmental sclerosis, refractory tufts, and capillary membrane wrinkling. A period of 1.5 years elapsed between the diagnosis of the glomerulopathy and the malignancy. The tumor was found to be at stage TIb. To our knowledge, this may be the first reported case of usual-type FSGS as paraneoplastic glomerulopathy (PG) preceding P-RCC. Because FSGS only sparingly affects the kidney and is a common glomerulopathy in adults, it is reasonable to complete comprehensive diagnostic studies and commence medically necessary treatment, especially in the background of other renal comorbidities. These preexisting comorbidities may be associated with malignancy very early in its course. The probability of RCC-associated paraneoplastic glomerulopathy is low, which means an already incidentally found renal mass may conceal a serpentine paraneoplastic syndrome. A more developed understanding of these manifestations can lead experienced clinicians to suspect and possibly uncover an insidious RCC before it advances.