title: Utility of negative oral contrast (milk with 4% fat) in PET-CT studies.
abstract: OBJECTIVE
  The aim of this study was to evaluate whether low-attenuation oral contrast agent (milk with 4% fat) in PET-CT gastrointestinal studies(GIT) improves the diagnostic accuracy.
  Traditional high-contrast oral agents like iodine solutions, and barium suspensions which due to overcorrection problems in PET-CT interpretation lowers the accuracy of diagnosis. Traditional low-attenuation oral contrast agents are water, air, fat containing agents used with 12.5% corn oil and polyethylene glycol. Volumen is a 0.1% barium suspension and has found favor in visualization of mural features as well as for GIT distension. Milk with 4% fat content has also been tested out in radiological studies and found to be as effective as Volumen. As the former is more easily available, palatable, and acceptable especially, by children it needed to be tested in the visualization of the GIT in the PET-CT scenario.
  
  
  METHODS
  Total of 112 patients were divided into 3 groups. Group I: No intervention (18 subjects) Group II: Water (55 subjects): All these patients had 500-750 ml of water 5-10 min before PET examination. Group III: Milk (39 subjects) 500 ml of milk (4% fat content with no additives) was given 40-45 min after 18F-Fluorodeoxyglucose (FDG) injection and another 500 ml 5 min before scan was started. For patients intolerant to milk the same procedure was carried out with soya milk. Group IV comparison with data with Volumen.
  
  
  RESULTS
  CRITERIA FOR EVALUATION OF GUT DISTENSION ON CT IMAGES: (0) No distension, (1) 1 cm distension, (2) 1-2 cm distension, (3) >2 cm distension. For the study analysis, % of patients with criteria 2 and 3 were considered as good visualization. Stomach distension was16%, 47%, 88%, 75% in Gr1-4 respectively, Duodenum-11%, 27% 88%, 86%, Jejunum-33%, 49%, 89%, 76%(*) Ileum-40%, 77%, 82%, 80%(*) and Colon-55%, 58%, 7 4%. Visualization of bowel wall with enhancement of stomach, duodenum, jejunum, and ileum and proximal colon was significantly better with milk than with water or no intervention. Intensity of FDG uptake was mild to moderate with no overcorrection in normal bowel loops and in patients with GIT lesions. Gaseous distension was not increased with milk as an oral contrast agent. Images of patients with bowel tumor was well-delineated with milk administration as the FDG uptake ratio of tumor to gut was high.
  
  
  CONCLUSIONS
  Distension and visualization of the stomach, duodenum, jejunum, and proximal bowel was significantly improved with milk as a low-attenuation contrast agent. Intensity of FDG uptake was not significantly increased in normal gut and delineation of tumor with increased FDG uptake was improved as overcorrection was minimal.
authors.affiliation: Department of Nuclear Medicine Centre, Institute of Functional Imaging and Research, Mangal Anand Hospital, Chembur, Mumbai, India.
authors.forename: Samuel Aban
authors.initials: SA
authors.lastname: Meyer
authors.forename: Sachin
authors.initials: S
authors.lastname: Gawde
keywords: Low attenuation gastrointestinal contrast; PET-CT of the gut; milk with 4% fat
references.citation: Radiology. 1987 Sep;164(3):653-6
references.pmid: 3615862
references.citation: Med Phys. 1998 Oct;25(10):2046-53
references.pmid: 9800714
references.citation: Radiology. 2004 Mar;230(3):879-85
references.pmid: 14764889
references.citation: AJR Am J Roentgenol. 1988 Apr;150(4):817-21
references.pmid: 3126628
references.citation: AJR Am J Roentgenol. 2008 May;190(5):1307-13
references.pmid: 18430848
references.citation: Radiology. 1996 Nov;201(2):365-70
references.pmid: 8888224
references.citation: Eur Radiol. 2000;10 Suppl 3:S377-80
references.pmid: 11001451
references.citation: Rofo. 1995 Jul;163(1):60-6
references.pmid: 7626755
references.citation: J Nucl Med. 2000 Aug;41(8):1369-79
references.pmid: 10945530
references.citation: J Nucl Med. 2003 Mar;44(3):412-6
references.pmid: 12621008
references.citation: J Nucl Med. 2001 Mar;42(3):533-4
references.pmid: 11337536
references.citation: Radiology. 1999 Jun;211(3):870-5
references.pmid: 10352618
references.citation: Acad Radiol. 2003 May;10(5):491-6
references.pmid: 12755536
references.citation: Radiat Res. 1977 Apr;70(1):58-81
references.pmid: 850736
references.citation: Eur Radiol. 2010 Jan;20(1):157-64
references.pmid: 19680659
references.citation: AJR Am J Roentgenol. 2002 Aug;179(2):477-81
references.pmid: 12130457