Meckel's Case 1 Answers

1) Name the radiopharmaceutical

99m-technetium in free pertechnetate form given intravenously

2) What are A & B?
3) Is there any evidence of a Meckel's diverticulum?

A is the stomach and B is the faint outline of the right kidney. There is no evidence of a Meckel's diverticulum (MD) but there is a rider. 80% of MD contain heterotopic gastric mucosa, which can cause peptic ulceration leading to pain, bleeding, and/or perforation. The parietal cells of the gastric mucosa takes up free pertechnetate and therefore a MD has to contain sufficient ectopic gastric tissue to be visualized. A diverticulum without ectopic gastric mucosa is unlikely to be symptomatic although ectopic jejunal, colonic, rectal, pancreatic, duodenal, and endometrial tissues have all been found.

4) Describe the imaging process for this type of scan

The patient should be fasted 6 to 12 hours and should empty their bladders. Other things that should be avoided prior to such a scan include GI barium studies, upper and lower endoscopy & prokinetic drugs (e.g. metoclopramide). Oral Cimetidine (or other acid suppressants) should be given prior to the study, helping block the intraluminal secretion of pertechnetate. This helps to improve the lesion to background ratio. Pentagastrin & Glucagon are not routinely used clinically.

From an anterior projection, dynamic scanning for 20-40 minutes with static views at 30-60 mins follows initial blood pool imaging.

5) What is the rational behind the lateral image?

Oblique or Lateral views may locating a MD behind the bladder and also help differentiate activity in the renal collecting system from a true diverticulum.

6) Who was Meckel and what exactly is a Meckel's diverticulum?

Although originally described by Fabricius Hildanus in 1598, it is named after Johann Friedrich Meckel, a German who established its embryonic origin between 1808 and 1820. The famous Meckel family spanned three generations and the grandfather described Meckel's cave.

An MD is the most common congenital abnormality of the small bowel and is a remnant of the omphalomesenteric or vitelline duct. MD occurs on the antimesenteric border of the ileum and is a true diverticulum because it contains all layers of the intestinal wall. The classical teaching is that of "2's".
However, the simple truth is rarely true or simple in that it occurs in 2% of people (although the prevalence has been estimated from 0.2-4%). It is 2 feet (60cm) from the ileocaecal valve, although it may be up to 1m. It is 2 inches (5cm) long, although on average, the diverticulum is 3 cm long but can be between 1-12cm. 2% of patients with an MD develop symptoms, although no one really knows, this may be as high as 4%. It classically presents in patients under the age of 2. It is true that presentation decreases linearly with age. One study found 45% of patients were less than 2. Although unusual after the age of 10, there is no upper age limit.

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The text is entirely the opinion of the author and does not necessarily reflect that of RUH NHS Trust or the Bristol Radiology Training Scheme. Website content devised by Paul McCoubrie.