Click on any image below to see an enlargement of that image.

Case 1: 32 year old woman with pelvic pain and fever six weeks after delivery by Cesarean section. Contrast enhanced axial image demonstrates pelvic floor cellulitis and osteitis of the pubic bones. MRI is more sensitive than CT in detecting and assessing extent of soft tissue infections.	Case 2: MR lymphangiogram performed for recurrent chylous pleural effusion demonstrates cisterna chyli in the upper abdomen (arrow).
Case 3: Fetal MRI performed at 38 weeks gestation demonstrates a teratoma of the neck (arrow). Prenatal imaging helped delivery planning and subsequent surgery and obviated the need for postnatal CT scanning.	Case 4: 18 year old woman with urinary incontinence. MRI demonstrates ectopic ureter (arrows).
Case 5: Infant with complex congenital heart disease. 3-dimensional MR angiogram demonstrates multiple ectopic spleens (arrow) not seen on CT that provided the diagnosis of polysplenia syndrome. Also shown, incidental persistent left SVC (arrowhead).	Case 6: MRCP demonstrates retained common bile duct stones (arrow) after cholecystectomy in a 16 year old with abdominal pain. CT scans in such patients are frequently not revealing.
Case 7a: Patient with abdominal pain and a history of surgery for biliary diversion. Image A demonstrates substantial signal within upper GI tract overlying biliary tree.	Case 7b: Image B demonstrates improved visualization of the common bile duct after the patient ingested blueberry juice (see Discussion below).

Above images are all original MR scans performed at Parkside MR Center.

Late last year the FDA distributed a Public Health Notification entitled, “Reducing Radiation Risk from Computed Tomography for Pediatric and Small Adult Populations”.¹ This notice acknowledged the significant potential public health risks associated with excessive radiation provided by computed tomography and recommended several steps to protect children and small stature adult patients from unnecessary exposure including:

• Optimize CT settings
• Reduce the number of multiple CT scans with contrast material
• Eliminate inappropriate referrals for CT or utilize procedures with less or no ionizing radiation such as MRI.

The FDA has made data available that help patients and referring physicians understand the relative radiation dose of diagnostic exams:²

Radiation Dose Comparison

Diagnostic Procedure	Effective Typical Dose (mSv)	Number of Chest X rays for Equivalent Effective Dose
Chest x ray (PA film only)	0.02	1
IVP	2.5	125
Barium enema	7.0	350
CT head	2.0	100
CT abdomen	10.0	500
MRI exams	0	0

Knowledge regarding effective radiation dose is crucial especially in children who, pound for pound, are more sensitive to the effects of radiation. Concerns over radiation dose are one of the main reasons that the FDA has failed to endorse whole body CT scanning as a screening tool.³

MR imaging does not involve ionizing radiation and can often provide an alternative to CT scanning when the diagnostic yield from CT is low or when multiple follow up scans are necessary. MR imaging, at usually a small premium in initial cost, is often more cost effective in the long run. MR imaging provides additional benefits. CT contrast agents are nephrotoxic and patients with renal insufficiency must be screened prior to undergoing contrast enhanced exams.⁵ MR contrast agents, unlike iodinated contrast agents used in CT, do not cause nephrotoxicity at standard dosages.⁴ Anaphylactoid reactions are also much less common with MR contrast than with iodinated contrast agents.⁴

Newer MR techniques can also help acquire information that was only formerly available from diagnostic exams utilizing ionizing radiation. For example, MR lymphangiography uses thin section T2 weighted imaging to visualize the cisterna chyli and lymphatic ducts without an injection of contrast. In cases where there is complex biliary anatomy, MRCP images can be improved with the use of a readily available contrast agent (blueberry juice) to help suppress signal from loops of bowel which are adjacent or overlie the biliary tree.⁶

References:
1. http://www.fda.gov/cdr/safety/110201-ct.html

2. http://www.fda.gov/cdrh/ct/risks.html

3. http:/www.fda.gov/cdrh/ct/

4. Runge, VM. The safety of MR contrast agent media: a literature review. Appl. Radiol. 2001; Suppl: 8-14.

5. Morcos, SK, Thomson, HS., Webb JA. Contrast-media induced nephrotoxicity: a consensus report. Contrast Media Safety Committee, European Society of Urogenital Radiology. Eur Radiol. 1999;9(8): 1602-3.

6. Schraa B., Hoed, D. Cholangiography with Blueberry juice. Magnetom Flash 2002, 2: 74.

For more information about reducing radiation risk and other case studies, call us at 847-696-7900.

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