Paediatrics. John Buscombe

Transcription

1 Paediatrics John Buscombe

2 Renal disease n Use of most radiopharmaceuticals limited as excreted via kidneys n However some role for infection specific studies in no-working kidneys Eg Infected polycystic kidney n However clearer role for renal cortical imaging

3 Renal cortical imaging n Use of agent which is filtered by glomerulus and then re-absorbed in tubules n Maps working nephrons n Tc-99m Glucohepatante, Tc-99m DMSA n Planar imaging adults and children

4 Image Acquisition Excellent quality DMSA scan acquired with child lying directly on a low energy high resolution collimator The ability to see the internal renal architecture is the hallmark of a high quality scan

5 Normal Variants - Horseshoe Kidney POST LPO RPO ANT LAO RAO note that the horseshoe is better visualised on the anterior and anterior oblique images

6 Normal Variants - Cross Fused Ectopia POST ANT LPO RPO as with ectopic kidneys, always perform anterior imaging

7 DMSA in acute infection n Tends to occur in the very young n Poor localising symptoms n May have difficulty obtaining clean urine n Majd in Washington University Hospital DC noted that acutely infected kidneys often have areas of swelling with reduced uptake of Tc-99m DMSA

8 Acute UTI (Majd et al) Note previous scan but new infection convex area-reduced uptake marked by long arrow

9 Scarring n Finding scarring is important n In many countries scarring from reflux and pyleonephritis is a major cause of hypertension and renal failure n Tends to occur in young children (<5) n Girls>boys n All children under 5 with suspected UTI must be investigated

10 DMSA imaging in scarring n Must be at least 6 months from previous infection n Antibiotics do not need to be stopped n Inject MBq of Tc-99m DMSA depending on weight n Scan 2.5 hours later Posterior and 2 posterior oblique images n Calculate divided function (if <45% be concerned)

11 Patterns of abnormality n Focal defects n Tend to be at upper and lower poles n Can just be smaller with diffusely decreased uptake n If either pattern seen antibiotics till 16 n Can re-scan n Also risk of extra scarring in pregnancy

12 Scarring

13 Abnormal DMSA Previous UTIs. Multiple scars in the right kidney which has globally reduced function..

14 Abnormal DMSA.Scarring progressed with further reduction in right renal function PITFALL do not call defects scars in the setting of a recent UTI; allow at least 3 but preferably 6 months before performing the DMSA to determine the presence of scarring

15 L 12% R 88% Abnormal DMSA Reflux nephropathy: Scarred, atrophic and poorly functioning left kidney Function left 12%, right 88%

16 POST Abnormal DMSA RPO Acute renal failure (reduced target to background ratio) provides the clue to the ARF

17 Abnormal DMSA Gross left hydronephrosis Functioning parenchyma still present IVU non-functioning Assessment of function on MAG3 will be inaccurate as ROI outside body contour

18 Milk scan n Used to look for gastro-oesophageal reflux in babies n Mix Tc-99m colloid with milk (inc breast milk n Give feed then image over 30 mins and look for reflux

19 Milk scan

20 Meckel s diverticulum n Very common maybe 40% of patients n Anywhere from pylorus to anus n Most described at or near junction of jejunum and ileum or in ileum n Pathological if contains ectopic gastric mucosa-rare (Denver children s have found 12 in 20 years (over 2000 studies)

21 Presentation-Denver n Normally under age 2 n Pain following food n Central abdomen n Next most common symptom obstruction n Bleeding in less than 20% n Never seen a positive over age 5

22 This is what it looks like

23 Imaging method n Best if patient comes after 4 hour fast n To reduced gastric movement Cimetidine may be used 30 minutes before scan do not use PPI n Position patient with abdomen under camera stomach at top of image n 30x60 second or 60x30 second frames n Inject MBq Tc-99 pertechentate (determined by patient weight) n Look for site of uptake appearing at same time as stomach mucosa n May only be seen in 1-2 frames so review dynamic imaging

24 Meckel s scan

25 Bilary atresia n Medical emergency n Cause of neonatal jaundice n If not settled in 10 days consider either biliary atresia n Differential is Gilbert s disease n In Bilary atresia if not corrected by 3 months kernictaris brain damage and fits

26 Performing study n Use 3 rd generation HIDA (Tc-99m mebrofenin or IODIDA n Prepare patient with 48 hours of phenobarbitone to stimulate bilary system and reduce possibility of false positive n Inject activity related to weigh (minimum 20MBq Tc-99m Mebrofenin)

27 Imaging n Image anteriorly n Can be done probe with child lying on camera head n Children often very passive n Image up to 24 hours n In no activity in small bowel by 24 hours positive study n Needs urgent operation

28 Positive study in BA n 24 hour image n Note good uptake n No excretion n Some bladder activity due to breakdown of circulating Tc-99m Mebrofenin

29 Bone imaging in children n Most indications need dynamic 3 phase imaging Osteomyelitis AVN Primary bone tumour n Static imaging to stage childhood cancer n Remember epiphyseal uptake

30 In AVN pinhole may help

31 Discitis in child

32 Osteosarcoma