Perforated appendicitis visualized by MRI

Clinical History

A 60-year-old female patient presented with pain in the right lower quadrant, which had persisted over the past 10 days, along with nausea and a loss of appetite.

Imaging Findings

The patient had been experiencing a right lower quadrant pain for 10 days. The pain, nausea and loss of appetite had been at their worst on the first day. Her appetite had improved within a few days, and the nausea had disappeared as well. However, there had still being pain during movement. On the 5th day, the patient had had strong bladder pain. A urine specimen taken at the emergency unit had tested positive for cystitis, and antibiotics had been administered. On the 10th day, the patient had additionally experienced fever and had been readmitted to the emergency department. The physical examination done this time revealed a right lower quadrant tenderness. Blood tests showed increased levels of leukocytes. The ultrasound examination showed a thickened bowel wall in the right lower quadrant. As a part of the current work-up, an MRI study was performed. The 0.6T MR imaging revealed the presence of a large oedematous lesion in the right lower quadrant, and a dilated appendix measuring 11 mm with thickened infiltrated walls (Figs. 1–3). The patient subsequently underwent a surgery. The surgery revealed a necrotic appendix with an abscess formation which was “of the size of an orange”. Microscopy confirmed an acute phlegmonous inflammation of the appendix.

Discussion

Acute appendicitis can be difficult to diagnose clinically due to atypical symptoms. While a number of patients undergo false-negative laparotomy [1], there are also cases, where the acute appendicitis is not identified in time, which may lead to a formation of an abscess [2]. In such a situation the symptoms may be unclear and an additional examination is required. Before surgery is undertaken, CT may be performed, to evaluate the condition [3]. Although the anatomical images obtained with the MRI and the CT techniques are similar, the MRI procedure has major advantages: it uses the non-ionizing technique, and it shows the extent of the oedema. MRI is also shown to be more specific in the determination of an acute appendicitis, relative to the ultrasound technique [4,5]. Appendicitis and abscess formation can be identified on MRI STIR sequences, which are especially sensitive to fluid collections. This method shows good resolution with slice which are 2 to 4 mm thick. The present case illustrates, how the 0.6T MRI technique can be used to identify an inflamed appendix with abscess formation. The use of a fat saturation technique together with the administration of a gadolinium containing i.v. MR contrast would have shown the exact size of the abscess, including the cavity and the membrane, but in the present case it was not found necessary.

Differential Diagnosis List

Final Diagnosis

Complicated acute appendicitis: perforation with abscess formation.

URL:	https://eurorad.org/case/3385
DOI:	10.1594/EURORAD/CASE.3385
ISSN:	1563-4086