Ultrasound in the diagnosis of abdominal abscesses

Noninvasive diagnosis of small bowel Crohn's disease: direct comparison of bowel sonography and magnetic resonance enterography

BACKGROUND

The diagnosis of small bowel Crohn's disease (CD) is performed by ileocolonoscopy, whereas the assessment of its extension can be achieved by radiologic studies or, noninvasively, by magnetic resonance (MR) enterography and bowel sonography (BS). However, few comparative studies exist directly comparing the diagnostic accuracy of BS and MRI. The aim of this study was to evaluate the diagnostic accuracy of BS and MRI for the diagnosis of small bowel CD.

METHODS

We prospectively performed a noninferiority diagnostic study including 234 consecutive subjects with suspected small bowel CD. All patients underwent IC (used as gold standard for diagnosis), BS, and MR enterography performed in random order by physicians who were blinded about the results.

RESULTS

The diagnosis of small bowel CD was made in 120 of 249 subjects (48%). Sensitivity, specificity, positive predictive value, and negative predictive value for CD diagnosis were 94%, 97%, 97%, and 94% for BS and 96%, 94%, 94%, and 96% for MR enterography, respectively. BS was less accurate than MR enterography in defining CD extension (r = 0.69), whereas the concordance in terms of CD location between the 2 procedures was high (k = 0.81). Also, MRI showed a fair concordance with BS about strictures (k = 0.82) and abscesses (k = 0.88), with better detection of enteroenteric fistulas (k = 0.67).

CONCLUSIONS

BS and MR enterography are 2 accurate procedures for the diagnosis of small bowel CD, although MR seems to be more sensitive in defining its extension. BS could be used to select the patients for subsequent MRI examination.

Anti-TNF-alpha treatments and obstructive symptoms in Crohn's disease: a prospective study

BACKGROUND

The development of symptomatic strictures in Crohn's Disease after anti-Tumour Necrosis Factor-α antibodies is undefined.

AIM

To assess, in a prospective longitudinal study, the frequency of sub/obstructions in Crohn's Disease patients after treatment with Infliximab or Adalimumab. Changes of small bowel lesions after these biological therapies were searched by ultrasonography.

MATERIALS AND METHODS

From January 2007 to October 2008, 36 Crohn's Disease patients with no previous sub/obstructions were treated with either Infliximab (n=13) or Adalimumab (n=23) for ≥12months (mean follow-up duration after the first treatment 23.2±6.8months). Small Intestine Contrast Ultrasonography was performed before and after treatment in 19/36 patients. Sonographic parameters included: bowel wall thickness, lumen diameter, bowel dilation and lesion extent.

RESULTS

Sub/obstructions developed in 3/36 patients treated with Infliximab (n=1) or Adalimumab (n=2), all with fibrostricturing Crohn's Disease. Sonographic parameters did not significantly change after treatment.

CONCLUSIONS

Sub/obstructive symptoms may develop in one tenth of Crohn's Disease patients treated with anti-Tumour Necrosis Factor-α antibodies, with no significant sonographic changes of the small bowel lesions.

Imaging of pediatric patients with inflammatory bowel disease

OBJECTIVE

The goal of this review is to examine the current imaging literature and develop basic imaging guidelines for evaluation of children with inflammatory bowel disease (IBD). The three following typical clinical scenarios in the imaging evaluation of IBD are considered: patient with an initial diagnosis of suspected IBD, the goals being to determine disease extent and severity and to differentiate Crohn disease from ulcerative colitis; patient with known IBD presenting with new acute symptoms (fever, peritonitis, leukocytosis) requiring urgent evaluation; and patient with known IBD presenting with nonacute symptomatic recurrence (abdominal pain, diarrhea), the goals being to assess the efficacy of the current treatment and to evaluate the possible need for additional medical or surgical intervention.

CONCLUSION

Imaging of pediatric patients with IBD must balance considerations of diagnostic accuracy against concerns about patient exposure to ionizing radiation and tolerance of the imaging technique. The imaging modality chosen depends on the clinical presentation and expected pathologic finding.

Noninvasive diagnosis of small bowel Crohn's disease: combined use of bowel sonography and Tc-99m-HMPAO leukocyte scintigraphy

BACKGROUND

Crohn's disease (CD) is frequently localized in the small bowel, with the diagnosis of disease and the assessment of its extension made by ileo-colonoscopy (IC) and small bowel enteroclysis (SBE). Transabdominal bowel sonography (BS) and Tc-99m-HMPAO leukocyte scintigraphy (LS) are increasingly used for the diagnosis of CD because of their minimal invasiveness, reproducibility, and acceptable costs.

METHODS

From March 2000 to July 2003, we performed IC, SBE, BS, and LS in 84 patients with either suspected or known small bowel CD.

RESULTS

Small bowel CD was present in 50 patients, whereas the other 34 patients received a different diagnosis. Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy were, respectively, 98%, 97%, 98%, 97%, and 0.97 for SBE; 92%, 97%, 98%, 88%, and 0.94 for BS; and 90%, 93%, 96%, 85%, and 0.92 for LS. In addition, the combined use of BS and LS led to overall sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of 100%, 93%, 96%, 100%, and 0.97, respectively. BS showed a fair concordance with SBE in terms of location (k = 0.71) and a correlation with the extension of the disease (r = 0.67, P < 0.001). LS showed a concordance with SBE with regard to location in about one-half the population (k = 0.54), whereas it was less effective than SBE in defining disease extension.

CONCLUSIONS

BS and LS are 2 accurate techniques for the diagnosis of small bowel CD, and their combined use can be recommended as an early diagnostic approach to patients in which the disease is suspected. SBE remains the best procedure for the definition of the location and extension of the disease.

Crohn's disease: a comparative prospective study of transabdominal ultrasonography, small intestine contrast ultrasonography, and small bowel enema

BACKGROUND

Small intestine contrast ultrasonography (SICUS), when performed after distention of the small bowel lumen with an iso-osmolar polyethylene glycol electrolyte-balanced solution, shows high sensitivity (100%) and specificity (97%) in detecting small bowel abnormalities in patients who have not received a diagnosis but in whom there is a suspicion of intestinal diseases. The diagnostic yield of SICUS remains to be established in detecting small bowel lesions in patients with proven Crohn's disease (CD) in comparison with transabdominal ultrasonography (TUS), and in relationship to the experience of the operator, using small bowel enema (SBE) as the "gold standard."

AIM

The aim of this study was to evaluate the diagnostic value of SICUS, when performed by a sonologist with 1 year of experience, and TUS, when performed by a sonologist with 10 years of experience, compared to SBE in the assessment of the site, extension, and stenosis of small intestinal lesions in CD patients.

PATIENTS AND METHODS

A total of 28 consecutive patients (men, 16; women, 12; age range, 21 to 60 yr) with a diagnosis of CD underwent TUS and SICUS, which were performed by 2 sonologists who were unaware of the radiologic findings, on the same day. SICUS was performed after the ingestion of 375 mL of a polyethylene glycol contrast solution. A standard SBE was performed on a different day by an expert radiologist who was unaware of the sonographic findings.

RESULTS

Sensitivities in the detection of small bowel lesions were 96% for TUS and 100% for SICUS. Compared with SBE, SICUS detected the presence of 4 lesions in the jejunum that had been missed by TUS. The mean (+/-SD) extent of the ileal disease was 22 +/- 12.5 cm when measured during SBE, 14.5 +/- 8.6 cm when measured during TUS, and 19.5 +/- 12.5 cm when measured during SICUS [P = 0.05 (SICUS versus SBE)]. The correlation of the extension of the lesions between SICUS and SBE (r = 0.88) was better than that between TUS and SBE (r = 0.64). The sensitivities of TUS and SICUS in the detection of at least 1 stricture were 76% and 94%, respectively. Sensitivity and specificity in assessing prestenotic dilatation were 50% and 100%, respectively, at TUS, and 100% and 90%, respectively, at SICUS.

CONCLUSION

In inexperienced hands, SICUS is a more accurate technique for assessing CD lesions, and the accuracy is better than that of TUS performed by an expert sonologist. The use of SICUS, instead of SBE, could be indicated for the follow-up of patients with CD.

Bowel wall thickness at abdominal ultrasound and the one-year-risk of surgery in patients with Crohn's disease

OBJECTIVES

Abdominal ultrasound can assess the extent and localization of Crohn's disease, and an increased bowel wall thickness is the most common finding. Our aim was to correlate bowel wall thickness at ultrasound, with the risk of short-term surgical outcome in patients with Crohn's disease.

MATERIALS AND METHODS

From 1997 to 2000 we performed ultrasound in 174 consecutive patients with Crohn's disease. Surgical operations were recorded over a 1-yr follow-up. Logistic regression analysis was performed to identify clinical and ultrasound risk factors for surgery.

RESULTS

Fifty-two patients underwent surgery within 1 yr. Indication for surgery was strictures in most of the cases. Median bowel wall thickness was higher in patients with surgery (8 mm) than those without surgery (6 mm) (p < 0.0001). A receiver operating characteristic (ROC) curve was constructed taking into account bowel wall thickness for selecting patients with a high risk of surgery. The optimized cut-off for equally important sensitivity and specificity was calculated at 7.008 mm. The binary regression analysis showed that CDAI > 150, absence of previous surgery, stricturing-penetrating pattern, the presence of intestinal complications, and intestinal wall thickness >7 mm were associated with an increased risk of surgery. Patients with intestinal wall thickness >7 mm at ultrasound had the highest risk (OR: 19.521, 95% CI: 5.362-71.065).

CONCLUSIONS

Data suggest that bowel wall thickness >7 mm at ultrasound is a risk factor for intestinal resection over a short period of time. Routine use of abdominal ultrasound during evaluation of patients with Crohn's disease may identify a subgroup that is at high risk for surgery. (Am J Gastroenterol 2004;99:1-7)

Modern imaging of Crohn's disease using bowel ultrasound

Technological advancement of ultrasound (US) equipments and understanding of bowel appearances with high resolution US during the last decade has led to consideration of this imaging procedure as an important tool for inflammatory bowel diseases assessment. In particular, Crohn's disease (CD) for its pathologic characteristics (that is, inflammatory infiltration of the entire bowel wall with possible extension to the surrounding mesentery) is the disease entity which has mainly taken advantage from this non-invasive, radiation-free technique. Beside correctly defining anatomic location and extension of CD lesions within the bowel in the majority of cases, US also shows perigut abnormalities and may demonstrate complications such as fistulas and abscesses. With the help of Power Doppler function, some additional information may be obtained about the local activity of the disease which is particularly useful in the presence of strictures. New US technologies (such as those using intravenous bolus contrast agents or oral nonabsorbable anechoic solutions) may further improve diagnostic capability of US in this context, thus probably revolutioning the diagnostic approach to this disease in the near future, particularly during follow-up in CD of the small bowel.

Contrast radiology, computed tomography and ultrasonography in detecting internal fistulas and intra-abdominal abscesses in Crohn's disease: a prospective comparative study

OBJECTIVE

Accurate assessment of intestinal complications of Crohn's disease (CD) is extremely important, both in clinical practice and in trials. The accuracy of radiographic and ultrasonographic diagnosis of internal fistulae and abscesses complicating CD is still debated and requires further investigation. We compared ultrasonography (US) and contrast radiography in detecting intestinal fistulae and abscesses complicating CD.

METHODS

A prospective study was carried out on 625 consecutive CD patients who underwent complete evaluation of the intestinal tract by means of colonoscopy and double contrast barium enema, small bowel enteroclysis, and abdominal ultrasound (US). Computed tomography (CT) was also carried out in cases of severe CD with clinical suspicion of septic complications. The accuracy of US, barium radiology, and CT in detecting internal fistulae and abscesses was assessed by comparing results with intraoperative findings in 128 consecutive patients who underwent operation immediately after diagnostic workup.

RESULTS

Internal fistulae and intra-abdominal abscesses were identified intraoperatively in 56 (43.7%) and 26 (20.3%) patients, respectively. Diagnostic accuracy of US and x-ray studies in detecting internal fistulae was comparable (85.2% vs 84.8%), with sensitivity of 71.4% for US and 69.6% for x-ray studies, and specificity of 95.8% for both. Combination of radiographic techniques and US significantly improved diagnostic accuracy in detection of internal fistulae. In severe cases of CD with clinical suspicion of septic complications such as abdominal mass or fever, the accuracy of US, barium studies, and CT was 88.5%, 80.3%, and 77%, respectively (p = ns). The presence of abscesses was correctly detected in 90.9% of cases by means of US and in 86.4% by CT (p = ns), although accuracy was higher for CT (91.8%) than for US (86.9%) because of false positive results in US studies.

CONCLUSIONS

Despite the fact that barium radiology is widely considered the method of choice in detection of internal fistulae, accuracy is not entirely satisfactory. Comparable accuracy was found for US and CT. The combination of barium and US studies, or the sole use of US in more CD patients with more severe disease, can reliably detect most internal fistulae and abscesses.

Ultrasonographic detection of intestinal complications in Crohn's disease

The aim of this study was to evaluate the sensitivity and specificity of ultrasound (US) in assessing the main abdominal complications of Crohn's disease (CD), such as strictures, fistulas and abscesses. A series of 98 consecutive inpatients with complicated and uncomplicated Crohn's disease, having undergone a complete endoscopic and radiographic evaluation of the intestinal tract, entered the study. In particular, in these patients the presence of strictures, fistulas, and abscesses, detected by means of colonoscopy, small bowel x-ray, double-contrast barium enema, and computed tomography, was also assessed by means of transabdominal US. US sensitivity and specificity in the assessment of stenosis of Crohn's disease were 74.4% and 93.1%, respectively. When ileal and colonic stenosis were considered separately, transabdominal US correctly assessed 84.6% of ileal stenosis and 58.8% of colonic stenosis. Eight of 12 fistulas were detected, but only 50% of enteroenteric fistulas were diagnosed. The presence of abscesses was correctly detected in 83.3% of cases by means of US. Our data suggest that US is a suitable complementary method for the detection of abdominal complications of Crohn's disease, such as strictures and abscesses; however, its usefulness in assessing enteroenteric fistulas seems to be fairly limited.

Ultrasound evaluation of hepatic and splenic microabscesses in the immunocompromised patient: sonographic patterns, differential diagnosis, and follow-up

High-dose chemotherapy, especially for bone marrow transplantation, causes a great degree of immunosuppression, and thus carries the risk for invasive fungal infections. Although hepatic and splenic involvement in disseminated candidiasis is frequent, involvement of these organs is rarely appreciated antemortem. During the last decade, focal hepatosplenic candidiasis has been recognized increasingly by ultrasound. We report the sonographic and clinical findings of 6 patients: 3 AML (acute myeloid leukemia), 2 NHL (non-Hodgkin's lymphoma), and 1 HD (Hodgkin's disease) who demonstrated multiple, small-nodule, hypoechoic lesions in spleen and/or liver after high-dose chemotherapy. All patients were in complete hematologic remission when the study was performed. Septic fever was unresponsive to antibiotic therapy. Granulocytopenia (< or = 1000/mm3) was seen for at least 10 days. However, the manifestation of hepatolienal microabscesses became apparent by ultrasound only after the neutrophil count returned to normal in all but 1 patient. Microabscesses decreased or disappeared on follow-up examination after antifungal treatment. Systemic candida infection was confirmed serologically. Sonographic-guided abscess biopsy (n = 3) revealed necrosis/abscess. Structural inhomogeneity of parenchymal organs was seen for several months after therapy.

The role of ultrasound scanning

Abdominal abscess, if left untreated, has a high mortality rate. Inadequate means of diagnosis and localization was responsible for this high mortality. Ultrasound now provides a simple non-invasive procedure permitting diagnosis with a high degree of sensitivity, although specificity is less commonly achieved. Abscesses do not have absolutely specific features, but given the appropriate clinical context and fine needle aspiration a diagnosis can be made in virtually 100% of cases, i.e. if the lesions can be identified and not obscured by bowel gas and examinations are not rendered difficult by surgical wounds and dressings. Diagnostic aspiration and therapeutic drainage are readily carried out using ultrasound guidance. Ultrasound is also of value in following the progress of lesions.

Case report: the ultrasound diagnosis of enterocutaneous fistula

The sonographic diagnosis of post-operative enterocutaneous fistula is presented. This has not previously been reported in the English literature.

Intra-abdominal sepsis: the role of radiology

A wide range of imaging tools is available for the investigation of abdominal sepsis. Plain films and barium studies alone are generally regarded as inadequate and most patients will require ultrasound, CT or nuclear medicine studies to locate the source of sepsis. The choice of imaging modality depends on several factors, most important of which are the clinical condition of the patient and the presence or absence of localizing signs and symptoms. Ultrasound has the advantage of being portable and is therefore probably the best initial imaging method for the critically ill patient. It should also be the first investigation in patients with signs and symptoms localizing to the right upper quadrant, renal areas, subphrenic spaces or pelvis. Transvaginal ultrasound is particularly useful in examining the pelvis. CT is the imaging modality of choice for the pancreas and retroperitoneum and in patients who are poor candidates for ultrasound or in whom visualization on ultrasound is inadequate. In patients with PUO or evidence of sepsis without localizing signs or symptoms, nuclear medicine studies in the form of 67Ga citrate or labelled white cell scans are useful to localize the septic focus, although in most cases CT or ultrasound will subsequently be required for detailed anatomical definition. Imaging techniques have an increasingly important role to play in the treatment of sepsis, and guided aspiration and drainage may be performed with a high degree of accuracy under ultrasound or CT guidance, eliminating the need for surgical intervention in many individuals.