IBD in Pediatric Patient

 

Background and Importance

IBD is one of the most common gastrointestinal diseases affecting pediatric patients in the developed world [1]. Crohn disease (CD) and ulcerative colitis (UC) are the two predominant subtypes of IBD, differing both in distribution of gastrointestinal tract involvement and depth of inflammation. Both disorders are most common in Europe and North America, where the ranges of incidence and prevalence are 3.1–14.6 cases per person-years and 26–199 cases per 100,000 persons for CD and 2.2–14.3 cases per 100,000 person-years and 37–246 cases per 100,000 persons for UC [1]. The classic teaching is that CD has a bimodal peak—the first peak in the second or third decade of life and a smaller second peak in the sixth or seventh decade. There is equal evidence, however, of a unimodal peak in the second or third decade that explains the high incidence in the adolescent population [1, 2]. CD is more common than UC among adolescents, and adolescents with UC tend to have more severe and extensive disease at presentation than their adult counterparts do: Approximately 90% of adolescents present with total colonic involvement [3]. Because the bowel disease in UC is confined to the colon, total colonic surgical resection is curative for patients whose condition is refractory to medical therapy. In contrast, the potential involvement of the entire gastrointestinal tract in CD often leads to lifelong intermittent symptomatic recurrence, and medical rather than surgical management is the primary therapy. No consensus exists regarding the optimal technique and imaging modality for evaluating IBD. The choice of imaging is informed by the clinical presentation of the patient. The choice of specific modality is based on the need to assess the distribution or activity of the disease and to detect extraluminal complications, such as intraabdominal abscess, perforation of bowel, and enteric fistula. Pediatric patients need additional attention to minimization of radiation exposure during imaging examinations because the chronic remitting and relapsing nature of IBD, especially CD, frequently necessitates repeat imaging with a resultant greater cumulative lifetime radiation exposure.

Ultrasound has the advantage of being a noninvasive test that imparts no ionizing radiation. High interoperator variability, however, is a practical consideration for determining its true diagnostic accuracy.

Targeted assessment of the bowel wall is usually performed with a high-frequency linear-array probe. As with fluoroscopy, with ultrasound, bowel loops can be observed over time for evaluation of peristalsis and function.

 

The ultrasound criteria for assessment of CD include assessment of wall thickness, loop stiffness, bowel dilatation, presence or absence of strictures, abnormal peristalsis, presence of fistula or abscess, and mesenteric inflammatory change. A previous meta-analysis revealed mean per patient sensitivity of 89.7% and specificity of 95.6% and per bowel segment sensitivity and specificity of 73.5% and 92.9%. Patient preparation is not usually required, although the studies are usually performed after the patient has fasted. Use of contrast material has been found to increase accuracy, and Doppler evaluation of bowel wall vascularity may help to determine the presence of disease activity or quiescence.

Poor visualization of the rectum and sigmoid colon, owing to the location of these structures in the pelvis, makes ultrasound less suitable for assessment of UC. The spatial resolution of ultrasound also is lower than that of barium studies.

In all of the ultrasound studies, wall thickness was the principal imaging parameter. The sensitivities and specificities were consistently much lower than with the cross-sectional modalities; the range of sensitivity was 0.48–0.8 and that of specificity was 0.57–0.93 across the three papers.

Ultrasound yields useful information on bowel wall abnormalities and can be accurate in experienced hands; however, because of low sensitivity and specificity and high interoperator variability, ultrasound is not recommended for first-line imaging in the three clinical scenarios posed.

The Three Typical Clinical Scenarios

1/ Pediatric patient: initial diagnosis of suspected inflammatory bowel disease, differentiation of Crohn disease from ulcerative colitis.

2/ Pediatric patient: known inflammatory bowel disease with new acute presentation (fever, peritonitis, leukocytosis).

3/ Pediatric patient: known inflammatory bowel disease with symptomatic recurrence (abdominal pain, diarrhea), not acutely ill.

Xem SIÊU ÂM TRONG BỆNH LÝ VIÊM RUỘT (IBD)

 

FIRST US TOOL for DENSE BREAST

Clinical Context

The National Cancer Institute estimates that approximately 40% of women undergoing screening mammography have dense breast tissue. High breast density hinders mammographic interpretation, which may delay detection of breast cancer until it is at a more advanced and difficult-to-treat stage.
Less-dense breasts have a high amount of fatty tissue, whereas dense breasts have a high amount of connective and fibroglandular tissue. Breast cancer and fibroglandular breast tissue both appear as solid white areas on mammograms, rendering interpretation more difficult.

Study Synopsis and Perspective

The US Food and Drug Administration (FDA) approved the first ultrasound device for use in combination with mammography in women with dense breast tissue.
The device, known as the somo-v Automated Breast Ultrasound System (ABUS), provides clinicians with an additional resource in screening women with dense breasts. The indication is limited to use in women who have a negative mammogram result and no symptoms of breast cancer.
Mammograms of dense breasts can be difficult to interpret, the FDA points out in its announcement of the approval.
"A physician may recommend additional screening using ultrasound, for women with dense breast tissue and a negative mammogram," said Alberto Gutierrez, PhD, director of the Office of In Vitro Diagnostic Device Evaluation and Safety at the FDA's Center for Devices and Radiological Health. "The somo-v ABUS is a safe and effective breast ultrasound tool when such screening is recommended."
Approximately 40% of women undergoing screening mammography have dense breasts, according to National Cancer Institute estimates. These women have an increased risk for breast cancer, with detection usually at a more advanced and difficult-to-treat stage, the FDA said.
In April, an expert advisory committee of the FDA voted unanimously to recommend the expanded use of the ultrasound device as a screening tool for women with dense breast tissue.
However, as reported by Medscape Medical News, some of the panel members had concerns about the device because of its automated nature. In contrast to handheld ultrasound, medical specialists who operate an automated ultrasound do not have to be imaging experts, Robert Faulk, MD, from Medical Imaging Consultants in Omaha, Nebraska, noted during the meeting. "For instance, obstetricians and gynecologists could do ABUS and interpret the results themselves, along with mammography findings," Dr. Faulk said. "That could have a deleterious effect on healthcare for many women," he added.
"ABUS as a screening tool could potentially be applied to 40 million women in the United States [with dense breasts], and if it were used by nonimaging specialists, the false-positive rates could go through the ceiling," said Daniel Kopans, MD, from Harvard Medical School in Boston, Massachusetts. Dr. Kopans commented that postmarket surveys of the false-positive rate from the new ultrasound device could provide important data on the effect of its use as a screening tool in women with dense breasts.
Dense breasts have a high amount of connective and fibroglandular tissue compared with less-dense breasts, which have a high amount of fatty tissue, the FDA explained.
Fibroglandular breast tissue and tumors both appear as solid white areas on mammograms, which can complicate interpretation. Dense breast tissue may obscure smaller tumors, potentially delaying detection of breast cancer, according to the FDA.
Ultrasound imaging has been proven capable of detecting small masses in dense breasts.
A clinical study has shown a statistically significant increase in breast cancer detection when images generated by this new device were reviewed in conjunction with mammograms compared with mammograms alone. The study involved board-certified radiologists who reviewed mammograms alone or in conjunction with device-generated images for 200 women with dense breasts and negative mammograms.
As part of the approval, the FDA requires that the manufacturer train clinicians and technologists using the new ultrasound device, and that the manufacturer provide each facility with a manual clearly defining system tests required for initial, periodic, and yearly quality-control measures.
The ultrasound works via a transducer that directs high-frequency sound waves at the breast. The specially shaped transducer of the device can automatically scan the entire breast in approximately 1 minute to produce several images for review, according to the FDA press materials.
More information on the new ultrasound device is available on the FDA Web site.

Clinical Implications

• The FDA has approved a new automated ultrasound device to be used in combination with mammography in women with dense breast tissue. This is the first ultrasound device approved for this indication. The specially shaped transducer of the device directs high-frequency sound waves at the breast to scan the entire breast in approximately 1 minute, automatically producing several images for review.
• The FDA has approved the ultrasound device for use only in women with negative mammography results and no symptoms of breast cancer. In these women, the device is a safe and effective breast ultrasound tool. Compared with mammograms alone, mammograms plus images generated by the new device interpreted by board-certified radiologists were associated with a statistically significant increase in breast cancer detection.
• Unlike handheld ultrasound, automated ultrasound does not have to be operated by an imaging expert. This may be a potential drawback in that medical practitioners without specialized radiographic training could use the new device and interpret the results themselves, along with mammography findings. This could dramatically increase false-positive rates. The FDA is requiring that the manufacturer train clinicians and technologists using the new ultrasound device, and that each facility is given a manual clearly defining system tests required for quality control.

Abstract: The idea of an automated whole breast ultrasound was developed three decades ago. We present our initial experiences with the latest technical advance in this technique, the automated breast volume scanner (ABVS) ACUSON S2000^TM. Volume data sets were collected from 50 patients and a database containing 23 women with no detectable lesions in conventional ultrasound (BI-RADS^®-US 1), 13 women with clearly benign lesions (BI-RADS^®-US 2), and 14 women with known breast cancer (BI-RADS^®-US 5) was created. An independent examiner evaluated the ABVS data on a separate workstation without any prior knowledge of the patients’ histories. The diagnostic accuracy for the experimental ABVS was 66.0% (95% confidence interval [CI]: 52.9–79.1). The independent examiner detected all breast cancers in the volume data resulting in a calculated sensitivity of 100% in the described setting (95% CI: 73.2%–100%). After the ABVS examination, there were a high number of requests for second-look ultrasounds in 47% (95% CI: 30.9–63.5) of the healthy women (with either a clearly benign lesion or no breast lesions at all in conventional handheld ultrasound). Therefore, the specificity remained at 52.8% (95% CI: 35.7–69.2). When comparing the concordance of the ABVS with the gold standard (conventional handheld ultrasound), Cohen’s Kappa value as an estimation of the inter-rater reliability was κ = 0.37, indicating fair agreement. In conclusion, the ABVS must still be regarded as an experimental technique for breast ultrasound, which definitely needs to undergo further evaluation studies.

Keywords: breast cancer, automated breast ultrasound, automated breast volume scanner, ABVS