Jin Do Huh

High Density Renal Medulla on Unenhanced CT : Significance and Relation with Hyd ration Status

Purpose : To assess the effect of hydration status on renal medullary attenuation and to evaluate theincidence of dense renal medulla, as seen on unenhanced CT. Material and Methods : We prospectively studiedunenhanced CT scans of 12 healthy volunteers. Obtained done after 10 hours and 15 hours of dehydration and afteroral intake of 2L of water. BUN/Cr, urine specific gravity, urine osmole and hematocrit were evaluated after 10hours of dehydration. CT images were reviewed for the presence of dense renal medulla and differential attenuationof dense renal and isodense medulla and cortex at the same level. The density changes of renal medulla afterhydration were evaluated. and CT findings were compared with the results of biochemical studies. In addition, weretrospectively reviewed the CT scans of 200 consecutive patients for evaluation of the incidence of dense renalmedulla. Results : In 8 of 12 volunteers, dense renal medulla was seen on CT scan after dehydration. Meanattenuation was 71.3 ±10.42HU after 10 hours of dehydration, 68.6 ±13.54HU after 15 hours, and 34.5 ±11.47HUafter hydration. No significant attenuation differences were detected between 10 hours and 15 hours ofdehydration, but significantly lower attenuation values were noted after hydration. For isodense medulla, the meanattenuation value was 35.7 ±7.9HU after 10 hours of dehydration, 39.58 ±9.66HU after 15 hours, and 36.58±7.77HU after hydration. The mean attenuation values of cortex were 35.9 ±5 . 9 5 H U after 10 hours ofdehydration, 37.58 ±5.95HU after 15 hours, and 37.08 ±9.75HU after hydration. With regard not only to durationof dehydration, but also ti hydration, no differences in attenuation values were noted for renal cortex orisodense renal medulla. However, higher density was noted in dense renal medulla than in isodense medulla orcortex for the same duration of dehydration. After hydration, complete resolution was seen at five of eight sitesand incomplete resolution at three of eight sites. There was no correlation between CT attenuation and laboratoryresults. Dense renal medulla was seen in 17 of 200 consecutive patients. Mean attenuation values were 64.06±8.38HU for dense renal medulla, 37.15 ±8 . 4 4 H U for isodense renal medulla and 35.36 ±8.13HU for cortex.Conclusion : For the same duration of dehydration, dense renal medulla showed a higher attenuation value thanisodense medulla or cortex, a finding which was completely or incompletely resolved after hydration. Inconsecutive patients, the incidence of dense renal medulla was 8.5% In conclusion, this in-cidence is aphysiological, variable, reflecting dehydration status.

Assessement of MR signal intensity of cranium and cervical spine bone marrow

The components of bore marrow change dramatically during lifetime. To evaluate the bone marrow of cranium and upper cervical spine , the authors retrospectively evaluated 300 examinations of cranium and the second cervical bone in patients without known bone marrow abnorm떠ity. T1 -weighted images were used to analyze the changes of lone marrow signal intensity according to the age and sex. The signal intensity of bone marrow of cranium increased most rapidly from birth to age of 10 years. Between 11 and 20 years of age , gradual increase of signal intensity was noted . There was minimal augment of signal intensity after age of 20 years. The examination of signal intensity of bone marrow of the cranium revealed slightly higher score in male than in female . The synchondrosis of the second cervical vertebra was visible in 97%. These results may be useful in the detection of abnormal bone marrow signal of cranium and upper cervical spine.

A case of intradural sparganosis in the thoracolumbar junction

Sparganosis is a rare parasitic disease usually involving muscle and subcutaneous tissue. Man seπes as an accidental intermediate host of sparganum , plerocercoid of spirometra subgenus. Spinal sparganosis is extremely rare. and only 4 cases have been reported in the Iiterature We describe a case of sparganosis affecting the intradural extramedullary space of the thoracolumbar junction Myelography revealed an irregular intradural filling defect with complete block below the TlO level. MRI showed a mild hyperintense lesion in the posterolateral portion of the intradural sac on T2WI and patchy enhancement on Gd-DTPA enhanced Tl Wl. The findings are consistent with granulation tissue related to sparganum. If there is a long segment involvement with a complete block at the cervicothoracic or thoracolumbar junction. no associated bony destruction. and a patient history of consuming snakes or frogs. sparganosis may be considered in the differential diagnosis.