The technetium white cell scan as an initial imaging investigation for evaluating suspected childhood inflammatory bowel disease

Nuclear medicine imaging of inflammatory/infective disorders of the abdomen

Different nuclear medicine modalities are currently used to study inflammatory and infective disorders of the abdomen. They are usually complementary to radiology and endoscopy, but they play a pivotal role in particular clinical situations. Several radiopharmaceuticals (e.g., 111In or 99mTc labelled white blood cells, monoclonal antibodies, human polyclonal immunoglobulins, 75Ga citrate) are commercially available, but they can not be used indifferently to study abdominal inflammatory disorders. The lack of comparative studies showing the accuracy of each radiopharmaceutical for the study of inflammatory/infective abdominal diseases does not allow the best nuclear medicine technique(s) to be chosen in an evidence-based manner. To this end we performed a meta-analysis of peer reviewed articles published between 1984 and 2004 describing the use of nuclear medicine imaging for the study of inflammatory bowel disorders, appendicitis and vascular graft infections. A guideline for the optimal radiopharmaceutical(s) to be used in each clinical condition and for different aims is provided.

Evaluation of 99mTc-HMPAO leukocyte scintigraphy in the investigation of pediatric inflammatory bowel disease

OBJECTIVE

To evaluate (99m)Tc-HMPAO leukocyte scintigraphy as an investigation for inflammatory bowel disease (IBD).

STUDY DESIGN

Scintigraphy was performed in 95 children undergoing investigation for IBD in a tertiary Gastroenterology Department. Diagnosis was based on conventional investigations including small bowel barium contrast radiology (BCR), upper gastrointestinal endoscopy (UGIE), colonoscopy, and endoscopic biopsy (the "gold standards"). IBD was confirmed in 73 (57 Crohn's disease; 10 ulcerative colitis; 6 indeterminate colitis) and excluded in 22 (controls). Scintigraphy was (1) evaluated as a screening test, (2) compared with individual conventional tests, (3) assessed for each gut segment.

RESULTS

Screening test: sensitivity 0.75 (95% CI, 0.63-0.85), specificity 0.82 (95% CI, 0.59-0.94), PPV 0.93, NPV 0.5. Comparison with BCR: sensitivity 0.87 (95% CI, 0.72-0.96), specificity 0.57 (95% CI, 0.39-0.73), PPV 0.69, NPV 0.2. Comparison with UGIE: specificity 0.9 (95% CI, 0.79-0.96), NPV 0.13 (sensitivity and PPV unavailable). Comparison with colonoscopy: sensitivity 0.57 (95% CI, 0.41-0.73), specificity 0.71 (95% CI, 0.54-0.85), PPV 0.71, NPV 0.42. Comparison with biopsies paralleled that with endoscopy. False negatives were especially common (NPV< or =0.2) in the proximal gut.

CONCLUSIONS

(99m)Tc-HMPAO leukocyte scintigraphy should not be relied on as a screening test for IBD because false negative results are common. This method is especially unreliable at detecting disease in the proximal gut.

Therapy of Crohn's disease in childhood

Crohn's disease in childhood is a chronic relapsing and remitting condition that can significantly impact on normal growth and development. This influences the choice of both initial and ongoing management. The goal of therapy is to induce and maintain remission with minimal side effects. Enteral nutrition as the sole therapy for active disease is effective in some children, thus avoiding the use of corticosteroids. In disease that is resistant to conventional treatment, immunosuppression or anti-tumour necrosis factor therapy is indicated. We review the use of these treatments and discuss the new therapies being developed, including antibodies, cytokines and probiotics.

Abdominal scintigraphy using technetium Tc 99m hexylmethylpropylene amine oxime-labeled leukocytes in patients with seronegative spondyloarthropathies

OBJECTIVE

To assess the potential benefits of technetium Tc 99m hexylmethylpropylene amine oxime (Tc 99m HMPAO)-labeled leukocyte scintigraphy in a group of patients with spondyloarthropathies (SpAs), overt gastrointestinal symptoms, and negative extensive endoscopic/radiologic test results.

PATIENTS AND METHODS

Ten patients with SpAs and overt gastrointestinal symptoms were included in this study. All patients underwent colonoscopy and small bowel barium studies, and results were negative. Abdominal scintigraphy with Tc 99m HMPAO-labeled leukocytes was performed in all the patients. Clinical and laboratory data and response to treatment was recorded.

RESULTS

The Tc 99m HMPAO-labeled leukocyte scintigraphy was positive in 5 of 10 patients, demonstrating uptake at the terminal ileum which is very suggestive of Crohn disease. The 5 scintigraphically positive patients were treated with sulfasalazine (SSZ). Four patients responded to SSZ with significant improvement of both gastrointestinal and joint symptoms.

CONCLUSIONS

In 5 of 10 patients with SpA and suspected inflammatory bowel disease on clinical grounds, evidence of inflammatory bowel disease was shown by scintigraphic studies in which conventional invasive procedures failed. Tc 99m HMPAO-labeled leukocyte scintigraphy should be considered in the evaluation of patients with SpA.

Inflammatory bowel disease

The epidemiology, aetiology, clinical features, diagnosis, and treatment of Crohn's disease and ulcerative colitis in children are reviewed, and areas for further research identified.

Technetium-99m HMPAO-labeled leukocyte imaging compared with endoscopy, ultrasonography, and contrast radiology in children with inflammatory bowel disease

BACKGROUND

The purpose of this study was to evaluate retrospectively the value of leukocyte-labeled scintigraphy, ultrasonography, and contrast radiography compared with endoscopy in children suspected of having inflammatory bowel disease (IBD).

METHODS

Twenty-eight children (17 boys; mean age, 10.2 years) with IBD based on standard colonoscopic, histologic, and radiologic criteria (16 with Crohn's disease, 5 with ulcerative colitis, 5 with nonspecific colitis, I with granulomatous disease, and I with Beh,cet's disease) were included. Endoscopic, ultrasonographic, and contrast radiologic examinations were realized for 28, 23, and 19 children respectively.

RESULTS

Sensitivity and specificity were 75% and 92% for leukocyte-labeled scintigraphy, 39% and 90% for ultrasonography, and 58% and 83% for contrast radiography. The authors noted discontinuous uptake for 14 of 15 true-positive results for patients with Crohn's disease and continuous uptake for 4 of 4 true-positive results for patients with ulcerative colitis. A negative correlation between scan activity index and Lloyd-Still clinical score was found for 11 patients with Crohn's disease (r = -0.77).

CONCLUSIONS

Leukocyte-labeled scintigraphy, a noninvasive and reproducible technique, is a useful tool in the diagnosis and therapeutic strategy of IBD, and provides information on the presence, the intensity, and the extent of the disease, particularly in the terminal ileum. Leukocyte-labeled scintigraphy may not replace colonoscopy with biopsies for diagnosis confirmation. Its reliability seems higher than that of ultrasonography.

Tc-99m HMPAO white blood cell scintigraphy in the assessment of the extent and severity of an acute exacerbation of ulcerative colitis

PURPOSE

Ulcerative colitis (UC) is a chronic inflammatory bowel disease with frequent exacerbations, including the risk for toxic megacolon and severe complications. In very active disease, colonoscopy should not be performed to assess the severity and the extent of the disease. The aim of the current study was to determine whether Tc-99m HMPAO-labeled white blood cell (WBC) scintigraphy can be used as an alternative to colonoscopy to determine the extent and the severity of the disease in critically ill patients.

METHODS

Twenty consecutive patients (7 women, 13 men; age 38.1 +/- 13.1 years) who had a severe attack of UC underwent scintigraphy on the day of admission. Leukocytes were labeled with 200 MBq (5.35 mCi) Tc-99m HMPAO. Planar anterior and posterior imaging of the abdomen was performed 45 and 120 minutes after WBC reinjection. The tracer uptake in the different colon segments was scored visually compared with bone marrow uptake. A symptom score was made and C-reactive protein was measured as a serologic marker of inflammation. Rectosigmoidoscopy with biopsy was performed within 24 hours of scintigraphy. Scintigraphic, endoscopic, and histologic results were compared for disease activity.

RESULTS

The mean symptom score was 12.7 (+/-0.7) on a scale of 21, and mean the C-reactive protein level was 6.8 (+/-1.2) mg/l. No significant difference was found between the scintigraphic score of the rectum and the endoscopic or the histologic score. The best correlation was found with the latter (r = 0.66, P < 0.01). Based on the results of scintigraphy, disease involved the left side of the colon up to the splenic flexure in 10 patients. The other patients had pancolitis.

CONCLUSIONS

Disease severity can be determined adequately by planar WBC scintigraphy in patients with severe attacks of UC. Because the presence and severity of disease correlates well with endoscopic and histologic findings, WBC scintigraphy can assess disease extent without the need for colonoscopy. This decreases the number and severity of complications that can occur in already critically ill patients.

Pediatric inflammatory bowel disease imaged with Tc-99m white blood cells

Studies have suggested that Tc-99m white blood cell (WBC) imaging is superior to contrast radiology for assessing the extent and activity of inflammatory bowel disease (IBD). The Tc-99m WBC scan seems ideally suited to obtain, in only one examination, a precise temporal snapshot of the distribution and intensity of inflammation, whereas radiographic methods of investigation tend to represent changes that are more chronic. The test is useful in children with inconspicuous signs suggesting IBD in whom laboratory test results are either normal or slightly abnormal. In those cases, a negative Tc-99m WBC study will obviate endoscopic investigations. The author's current experience, in more than 500 patients, indicates that the Tc-99m WBC scan is a virtual gold standard to establish, or exclude, the diagnosis of IBD. The minimal invasiveness of the Tc-99m WBC scan makes it an especially attractive method for evaluating children with IBD. It is economical compared with endoscopy, and its diagnostic sensitivity is excellent. The ability to evaluate the small and large bowel simultaneously is an important advantage for the patient. In conclusion, the Tc-99m WBC scan is a useful tool to evaluate IBD and should be added to the clinician's investigative armamentarium.

Therapy of Crohn's disease in childhood

Crohn's disease in childhood is a chronic relapsing condition with a high morbidity. Growth failure is common. The aim of therapy is to induce and then maintain disease remission and thereby promote well-being and normal growth and development. Enteral nutrition (either polymeric or elemental) is effective and used as initial therapy. This is employed as sole therapy over a 6- to 8-week period followed by a period of controlled food reintroduction. The relapse rate is high and further courses of enteral nutrition or alternative therapies are frequently required. Corticosteroids are also effective as initial therapy and are required in difficult cases but there are problems with their long term use, particularly their adverse effects on growth. Many patients develop either corticosteroid-dependent or corticosteroid-resistant disease. In this instance, additional immunosuppression, such as azathioprine, can be used. Surgery is required for those patients with disease resistant to medical therapy and this will result in remission; however, the relapse rate with surgery is high. There are many areas for future research. Very little is known about why enteral nutrition works, how long it should be given or its role as maintenance therapy. Newer immunosuppressive strategies based on cytokine modulation may be helpful in children once more experience is gained from their use in adults.

Colonoscopy and technetium-99m white cell scan in children with suspected inflammatory bowel disease

OBJECTIVES

To determine the utility of the technetium-labeled autologous white cell scintigraphy (Tc-WCS) for detecting intestinal inflammation in children with suspected inflammatory bowel disease (IBD). Tc-WCS was compared with colonoscopy and histologic examination.

STUDY DESIGN

Forty-eight children (26 boys; median age, 10 years; range, 2-17 years) with symptoms and signs suggesting IBD had colonoscopy with exploration of terminal ileum and mucosal biopsies. The scans were judged to be abnormal if activity was seen in the gut within the first hour.

RESULTS

Twenty-one patients had a diagnosis of IBD (Crohn's disease, 13; ulcerative colitis, 5; indeterminate colitis, 3); results of scintigraphy were positive in 16 and negative in 5 (sensitivity, 76.2%); the latter had a moderate degree of intestinal inflammation. In 27 patients, IBD was ruled out. Results of scintigraphy were negative in children with non-specific colitis and in those with lymphoid hyperplasia of the terminal ileum, whereas results were positive in 6 of 12 patients with spondyloarthropathy. In children with IBD, there was a significant correlation between results of scintigraphy and endoscopy for the intensity of inflammation (r = 0.70); however, there was a poor correlation regarding the number of involved segments (r = 0.30) because in 16 patients, endoscopy revealed additional diseased segments as compared with scintigraphy.

CONCLUSIONS

A positive Tc-WCS result indicates the presence of an inflammatory process of the gut, whereas a negative test result does not rule out intestinal inflammation, especially when the latter is of moderate degree. Colonoscopy and biopsy are the investigations of choice to establish the diagnosis of IBD and are superior to Tc-WCS in assessing topographic extension of IBD.

Technetium leukocyte imaging in inflammatory bowel disease

Technetium-99m white blood cell ((99m)Tc-WBC) imaging has been part of the initial evaluation and follow-up of more than 400 children presenting with inflammatory bowel disease (IBD) at Children's Hospital of Pittsburgh. Studies have suggested that (99m)Tc-WBC imaging is superior to contrast radiology in assessing the extent and activity of IBD. With only one examination, (99m)Tc-WBC imaging is ideally suited to obtain a precise temporal snapshot of the distribution and intensity of inflammation, whereas radiography tends to detect more chronic changes. There is a high correlation between (99m)Tc-WBC imaging findings and those of endoscopy. When total colonoscopy cannot be completed satisfactorily or when contrast radiography findings are negative or equivocal, scintigraphy can confirm the presence of ileitis or right-sided colitis. Occasionally, (99m)Tc-WBC imaging is useful in differentiating Crohn's disease from ulcerative colitis. Some studies have suggested that (99m)Tc-WBC imaging is useful as an initial screening modality to exclude IBD. Technetium-99m WBC imaging is noninvasive, practical, safe, requires no bowel preparation, and entails less radiation exposure than contrast radiology or computed tomography.