Topical "Saw-tooth" colon on barium enema is seen in

Ans. a (Colonic diverticulosis) (Ref. Radiology secrets 2nd ed., 135)COLONIC DIVERTICULOSIS# Colonic diverticula are protrusions of mucosa and submucosa through areas of colonic wall weakness, primarily where the end arteries perforate the colonic wall (on the mesenteric side of the antimesenteric teniae).# The diverticula protrude into the pericolic fat, separated from the pericolonic fat by a thin layer of longitudinal muscle.# In patients with diverticulosis, diverticula are found in the -- sigmoid colon in 90% of patients,- descending colon in 30%- throughout the colon in 16%.# The longitudinal muscle layer of the colon is primarily divided into three bands, termed the teniae coli.# In diverticular disease, elastin deposits between normal muscle fibers in the teniae coli.# Macroscopically, the teniae coli are shortened and thickened, resulting in overall shortening and straightening of the colon and redundancy of the circular muscle fibers and mucosa.# The term diverticular disease implies circular muscle bunching. The term diverticulosis implies presence of diverticula with or without circular muscle bunching.# Single-contrast barium enema is the best investigation for detecting colonic diverticuli.0# Ba enema shows circular muscle thickening and diverticulosis of the sigmoid colon.- The lumen has a "Saw-toothed", "zigzag," "accordion-like," or "concertina-like" appearance created by thick folds of circular muscle and redundant mucosa protruding into the lumen.# Nevertheless, Multislice CECT is the best investigation for diverticulitis and its complications.e