duplicated gb is often picked up on ultrasonography , however there are a lot of differentials . since , 99 m tc hida follows hepatobiliary physiology , any tracer concentration in gb fossa is confirmatory for presence of gb , thus in turn increasing the specificity in picking up anatomical variants as in our case . a 15 year old boy presented with intermittent pain in right hypochondrium for a week . physical examination revealed no local tenderness . ultrasonography ( usg ) of the abdomen revealed two cystic formations in the gall bladder ( gb ) fossa with no distinct visualisation of cystic duct . after fasting for 6 - 8 hours , 5 mci of 99 m tc mebrofenin ( hida ) was injected intravenously and dynamic images were acquired for 1 hour , at a frame rate of 1 minute / second . images revealed normal hepatocellular tracer extraction with visualization of the hepatic and common bile ducts at 10 minutes . two foci of tracer uptake were seen in the region of gb fossa [ figure 1a - arrows ] at 15 minutes , which persisted till the end of the study . anterior static pre fatty meal image showed two intense foci of tracer uptake in gb fossa [ figure 1b - arrow ] . post fatty meal anterior static image showed reduction in size and counts in both structures in gb fossa [ figure 1c - arrows ] . detection of two globular structures in gb fossa , which contract after fatty meal , is specific for duplicated gb . it was further confirmed by drawing regions of interest ( rois ) on gb moieties , on pre and post meal images , which showed reduction in counts by more than 50% . since gb visualization was within normal time range , with preserved contractile function post fatty meal , patient was kept on medical therapy , low fat diet and antibiotics , and follow up was recommended . ( a ) dynamic hida scan images showing visualisation two separate foci in gb fossa at 15 minutes ( arrows ) and normal intestinal tracer excretion ( thick arrow ) ( b ) pre meal anterior static image showing two separate gb fossa moieties ( arrows ) ( c ) post fatty meal anterior static image showing significant tracer excretion following gb contraction confirming that the moieties are duplicated gb moieties an 8-year - old boy presented with recurrent abdominal pain and occasional vomiting since a few months . usg of the abdomen showed two pear shaped structures in the gb fossa , seen as two adjacent anechoic structures oriented in the same plane [ figure 2a - arrows ] ; consistent with duplicated gb , with separate cystic ducts . coronal magnetic resonance imaging ( mri ) showed the duplicated gb [ figure 2b - arrows ] . after adequate preparation , serial static 99 m tc mebrofenin hepatobiliary study was performed ; images being acquired in anterior , right lateral and right anterior oblique views every 2 - 5 minutes . static anterior images showed two distinct moieties in gb fossa [ figure 3-arrow and arrowheads ] , confirming the diagnosis on usg and mri , of duplicated gb . post meal static image [ figure 4b ] was compared with pre meal static image [ figure 4a ] , latter showed significant reduction in gb counts ( arrows ) , suggesting normal contraction of the gb , thus ruling out obstruction . ( a ) ultrasonography showing two anechoic structures in gb fossa ( arrows ) ( b ) duplicated gb seen on coronal mri ( arrows ) serial static hida images in anterior , right lateral and right anterior oblique views confirming the presence of duplicated gb ( arrows and arrowheads ) static anterior view ( a ) pre meal ( b ) post meal , showing tracer excretion following gb contraction a 15 year old boy presented with intermittent pain in right hypochondrium for a week . physical examination revealed no local tenderness . ultrasonography ( usg ) of the abdomen revealed two cystic formations in the gall bladder ( gb ) fossa with no distinct visualisation of cystic duct . after fasting for 6 - 8 hours , 5 mci of 99 m tc mebrofenin ( hida ) was injected intravenously and dynamic images were acquired for 1 hour , at a frame rate of 1 minute / second . images revealed normal hepatocellular tracer extraction with visualization of the hepatic and common bile ducts at 10 minutes . two foci of tracer uptake were seen in the region of gb fossa [ figure 1a - arrows ] at 15 minutes , which persisted till the end of the study . anterior static pre fatty meal image showed two intense foci of tracer uptake in gb fossa [ figure 1b - arrow ] . post fatty meal anterior static image showed reduction in size and counts in both structures in gb fossa [ figure 1c - arrows ] . detection of two globular structures in gb fossa , which contract after fatty meal , is specific for duplicated gb . it was further confirmed by drawing regions of interest ( rois ) on gb moieties , on pre and post meal images , which showed reduction in counts by more than 50% . since gb visualization was within normal time range , with preserved contractile function post fatty meal , patient was kept on medical therapy , low fat diet and antibiotics , and follow up was recommended . ( a ) dynamic hida scan images showing visualisation two separate foci in gb fossa at 15 minutes ( arrows ) and normal intestinal tracer excretion ( thick arrow ) ( b ) pre meal anterior static image showing two separate gb fossa moieties ( arrows ) ( c ) post fatty meal anterior static image showing significant tracer excretion following gb contraction confirming that the moieties are duplicated gb moieties an 8-year - old boy presented with recurrent abdominal pain and occasional vomiting since a few months . usg of the abdomen showed two pear shaped structures in the gb fossa , seen as two adjacent anechoic structures oriented in the same plane [ figure 2a - arrows ] ; consistent with duplicated gb , with separate cystic ducts . coronal magnetic resonance imaging ( mri ) showed the duplicated gb [ figure 2b - arrows ] . after adequate preparation , serial static 99 m tc mebrofenin hepatobiliary study was performed ; images being acquired in anterior , right lateral and right anterior oblique views every 2 - 5 minutes . static anterior images showed two distinct moieties in gb fossa [ figure 3-arrow and arrowheads ] , confirming the diagnosis on usg and mri , of duplicated gb . post meal static image [ figure 4b ] was compared with pre meal static image [ figure 4a ] , latter showed significant reduction in gb counts ( arrows ) , suggesting normal contraction of the gb , thus ruling out obstruction . ( a ) ultrasonography showing two anechoic structures in gb fossa ( arrows ) ( b ) duplicated gb seen on coronal mri ( arrows ) serial static hida images in anterior , right lateral and right anterior oblique views confirming the presence of duplicated gb ( arrows and arrowheads ) static anterior view ( a ) pre meal ( b ) post meal , showing tracer excretion following gb contraction duplication of gb is a rare congenital anomaly , occurring in about one per 4,000 births . differential diagnosis based on sonographic findings include gallbladder diverticula , gb fold , phrygian cap , choledochal cyst , pericholecystic fluid , focal adenomyomatosis , and intraperitoneal fibrous bands , which results in a diagnostic dilemma . 99 m tc hida is a bile analogue which gets metabolised by the biliary pathway . following a fatty meal , there is a physiological gb contraction , resulting in tracer excretion into the common bile duct and subsequently into gut . thus , nuclear hida scan is a physiological and specific modality to pick up anomalies in the hepatobiliary tree and gb . also , contraction of both the gb moieties following fatty meal , rules out the presence of choledochal cyst , which is a close differential and confirms presence of duplicated gb . in cases where duplicated gb is diagnosed on usg , hida scan is done to rule out obstruction , as prevalence of cholelithiasis and obstruction is more in association with duplicated gb . both cases highlight the role of hida scan in detecting duplicated gb . in addition , in case 1 , where usg findings are equivocal , a dynamic hida study with fatty meal provides diagnostic accuracy ; whereas , in case 2 , where duplicated gb is diagnosed , serial static hida study helps to rule out associated obstruction .