Colon Cutoff Sign

Fig. 1: Supine abdominal radiograph in a 30-year-old man with acute abdominal pain shows gas in the transverse colon (C) with an abrupt termination at the level of splenic flexure (arrowheads). The more distal colon is decompressed. S = stomach
Fig. 2: Axial CT image of the same patient (done a few hrs later) shows extensive inflammation and necrosis of the pancreas (arrows) with free fluid in the abdomen (stars).

What is Colon Cutoff Sign?
Abrupt termination of gas in proximal colon at the level of the splenic flexure.
Applied to radiography, CT and contrast enema studies

What Can Cause Colon Cutoff Sign?

• Most common = acute pancreatitis
• True colonic obstruction e.g. colonic malignancy
• Other causes of colonic inflammation

Why Does It Occur?
In acute pancreatitis, inflammatory exudates in retroperitoneal space extend into 'phrenicocolic ligament' causing spasm of the splenic flexure wherer the colon returns to retroperitoneum. (Remember - transverse colon in peritoneal cavity, descending colon in retroperitoneum, phrenicocolic ligament is a transition point where transverse and descendinc colon is separated)

Available in Podcast (Thai language only): website | iTunes

Reference:
Pickhardt P. The colon cutoff sign. Radiology 2000;215:387.

When to Obtain Ankle Radiographs

Problems:
- Ankle radiography was the third most common study ordered in the emergency department.
- Majority of patients with ankle radiographs did not receive adequate physical examination before radiographs were obtained.
- Only 17% of extremity radiographs obtained had abnormality that would alter treatment.

Guidelines for Obtaining Ankle Radiographs (Ottawa Rule)

1. Inability to bear weight immediately after the injury OR
   
2. Point tenderness (over medial malleolus, posterior edge or inferior tip of lateral malleolus, talus, calcaneus) OR
   
3. Inability to ambulate for four steps in the emergency room

Sensitivity approaches 100% in excluding significant ankle fractures
Decrease number of ankle and midfoot radiographs by 19% - 36%

Podcast of this post is available in iTunes Store or a website.

Reference:
ACR Appropriateness Criteria "Suspected Ankle Fracture", revised 2005.

The Scan That Didn't Scan - An Article from Today's NY Times

Full article can be read at the New York Times
Picture above is from the New York Times
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A very interesting article in one of the most read newspapers in the USA described an experience of the author (and a friend) having MRI scans at some New York hospitals. The author injured the foot and received the first MRI scan at a 'local' radiology center. They found nothing wrong and she was treated with medication without limiting activity. However, she hurt so much and got a second opinion at the Hospital for Special Surgery in New York. The second scan showed a stress fracture. The first scan quality was probably not good enough to detect the lesion (it missed the lesion), or the qualification of the first radiologist (general radiologist) is not enough.

The article also included several opinions from prominent radiologists including Dr Forman from Yale, Drs. Gazelle and Thrall from MGH.

I think the article is very important and any radiologists should read it because:

• Being optimistic, the story brought radiologists to the light, criticized by lay people. It emphasizes how important radiologists are in the practice of medicine.
• It teaches us that quality of the images produced, and experience of radiologists are very important for interpretation and subsequent patient care. Good quality images = good quality interpretation. Good training of radiologists, technologists and good-quality scanners are crucial.
• It raises an issue of the training and qualification of radiologists. One day, patients may ask "Who read my scans? Is he or she qualified for this interpretation?" Strangely, this article coincides with a few articles in the current issue of JACR (Journal of the American College of Radiology) talking about sub-specialization in Radiology.
  
• It also tells us to 'treat the patient, not the images'. Lesson learned for the clinicians. Like Dr. Thrall said in this article, "scans, as good as they are, are not perfect."

Listen to an accompanied Podcast HERE (in Thai language)