Medical Image of the Week: Polysomnogram Artifact

Figure 1. Thirty second polysomnogram epoch showing artifact in lead O1M2 (black arrow).

Figure 1. Ten second polysomnogram epoch showing artifact in lead O1M2 (black arrow).

A 54 year-old man with a past medical history of attention deficit hyperactivity disorder (ADHD), low back pain, and paroxysmal supraventricular tachycardia presented to the sleep laboratory for evaluation of sleep disordered breathing. Pertinent medications include fluoxetine, ambien, and clonazepam. His Epworth sleepiness score was 18. He had a total sleep time of 12 min. On the night of his sleep study, the patient was restless and repeatedly changed positions in bed. 

Figures 1 and 2 show the artifact determined to be lead displacement of O1M2 after the patient shifted in bed, inadvertently removing one of his scalp electrodes. The sine waves are 60 Hz in frequency. Once the problem was identified, the lead was quickly replaced to its proper position.

Jared Bartell¹, Safal Shetty, MD^1,2, and John D. Roehrs, MD^1,2

¹University of Arizona Medical Center

²Southern Arizona VA Health Care System

Tucson, AZ

Reference as: Bartell J, Shetty S, Roehrs JD. Medical image of the week: polysomnogram artifact. Southwest J Pulm Crit Care. 2015;10(2):95-6. doi: http://dx.doi.org/10.13175/swjpcc014-15 PDF

Medical Image of the Week: Bilateral Symmetrical Nephromegaly

Figure 1. Axial section from the CT scan through the abdomen. Also seen is the "misty mesenteric sign" (white arrow) and pancreatomegaly (black arrow).

Figure 2. Coronal section of the abdominal CT scan showing the diffuse symmetric nephromegaly.

A 70-year-old man was evaluated for symptoms of fatigue, abdominal pain and a 20 pound weight loss. Abdominal imaging was obtained as a part of work up and showed hepatomegaly, splenomegaly, nephromegaly, mesenteric infiltration and diffuse lymphadenopathy (Figures 1 and 2).

A liver biopsy was obtained and a diagnosis of diffuse large B-cell lymphoma was made. The patient opted for a palliative approach and was discharged to an inpatient hospice after a short hospital stay.

Bilateral symmetrical nephromegaly is an uncommon radiological finding in adults, and in the absence of infection, the differential includes HIV-associated nephropathy, amyloidosis, lymphoma, acute tubular necrosis and lupus nephritis.

Also seen in Figure 1 is the "misty mesenteric sign" (white arrow) which is a term used to describe the CT appearance of mesenteric fat with increased attenuation and stranding (1).  A number of processes can lead to the appearance including infiltration by inflammatory cells, edema, lymphatic accumulation, hemorrhage, tumor infiltration, and fibrosis.  

Tammer Elaini MD¹, Muna Omar MD² and Bhupinder Natt MD²

¹Department of Internal Medicine

²Division of Pulmonary, Allergy, Critical Care and Sleep Medicine

University of Arizona Medical Center

Tucson, AZ

Reference

1. Corwin MT, Smith AJ, Karam AR, Sheiman RG. Incidentally detected misty mesentery on CT: risk of malignancy correlates with mesenteric lymph node size. J Comput Assist Tomogr. 2012 Jan-Feb;36(1):26-9. [CrossRef] [PubMed] 

Reference as: Elaini T, Omar M, Natt B. Medical image of the week: bilateral symmetrical nephromegaly. Southwest J Pulm Crit Care. 2015;10(2):93-4. doi: http://dx.doi.org/10.13175/swjpcc013-15 PDF