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Radiological Anatomy Second YearILOs ● Imaging Techniques ○ Basics: (XR, CT, MRI, Nuclear, USS) ○ AXR ○ Abdominal CT ○ Barium swallow Link to Chat only (can ○ Barium enema take part in polls but slides and take part in see ○ ERCP/MRCP cannot see slides) polls) ○ Ultrasound ○ Cystography ● Anatomy ○ Basic GI ○ Upper GI ○ Lower GI ○ Biliary ○ Renal ○ Genitourinary We’ve included cases to illustrate the anatomy and make it more memorable, we do not expect you to recognise these conditions on imaging for your exams!!Imaging T echniques The BasicsX-Ray ● What is it? ○ X-ray radiation is passed through the body. ○ Areas with high levels of density block the radiation - appear white. ■ Metal (very white), bone or calcium (white) ○ Soft tissues allow some radiation to pass through - appear gray. ■ Fat, soft tissue, fluid ○ Air allows all radiation to pass through - appear black. ■ Lungs, bowel gas ● Indications ○ Boney pathology ■ Fractures, dislocations ○ First line investigations ■ CXR, AXR ● Benefits ○ Fast (seconds) ● Negatives ○ Uses ionising radiation + ○ Structures overlapX-Ray ● What is it? ○ X-ray radiation is passed through the body. ○ Areas with high levels of density block the radiation - appear white. ■ Metal (very white), bone or calcium (white) ○ Soft tissues allow some radiation to pass through - appear gray. ■ Fat, soft tissue, fluid ○ Air allows all radiation to pass through - appear black. ■ Lungs, bowel gas ● Indications ○ Boney pathology ■ Fractures, dislocations ○ First line investigations ■ CXR, AXR ● Benefits ○ Fast (seconds) ● Negatives ○ Uses ionising radiation + ○ Structures overlapCT ● What is it? ○ Uses rotating X-ray source and detector ■ Creates 360 degree views of body structures. ● Indications ○ Trauma (CT brain for bleed) ○ Malignancy ○ Assessing abnormalities seen on X-ray ● Benefits ○ Fast (often <10 minutes) ○ Structures can be viewed in different planes ■ Overlapping structures not an issue ○ 3D reconstructions ● Negatives ○ Ionising radiation +++MRI ● What is it? ○ Powerful magnet and radiofrequency pulses through the body. ○ Protons (hydrogen ions) are excited by the signal. ○ Protons relax after each pulse and give off a signal that is detected by the receiver. ○ Highly detailed images are created. ■ ● Indications ○ Soft tissue ■ Brain, MSK (muscles, ligaments) ● Benefits ○ Good at imaging soft tissues. ○ No ionising radiation ● Negatives ○ Slow (often 10+ minutes) ○ Patient must remain motionless ○ Claustrophobic ○ Ferrous metallic objects cannot go near the scanner ■ May include pacemakers, cochlear implants, prosthetic heart valves ○ Not available at smaller hospitalsMRI T1 vs T2 ● T1 fat is bright. ● T2 fat and water are bright. ○ E.g. CSF Sarah Connor, you’re terminated!CT (and MRI) Planes ● Coronal ○ Crown ● Sagittal ○ Arrow ○ Side on view ● Axial ○ AxleUltrasound ● What is it? ○ Sound waves travel inside patient and bounce back to the probe ○ Different tissues reflect different amounts of the signal. ○ A picture is created. ○ Use of the Doppler effect can show direction and velocity of blood ● Indications ○ Good at differentiating between cysts (fluid filled) or solid lesions ○ Kidneys ○ Pregnancy scans ○ Cannula placement ● Benefits ○ No ionising radiation ● Negatives ○ Operator error ○ Cannot see past air and bone Nuclear Medicine ● What is it? ○ Patients ingest or are injected with radioactive substance. ■ E.g. radioactive substance may accumulate in tumours. ○ This radioactive substance can be detected and an image created. ○ Often combined with CT to created a hybrid image showing anatomy and physiology (PET-CT). ● Indications ○ Evaluation of masses ?cancer ■ Cancers are highly metabolically active and likely to take up radioactive substance and appear bright. ○ Evaluation for metastatic disease ○ Evaluation of lung disease ■ Patients breathe in radioactive substance, allows dead space in lungs to be seenBasic GI AnatomyAbdominal X-Rays ● Indications ○ Emergency presentations ■ Toxic megacolon ■ Bowel obstruction ■ Ingestion of foreign body ○ Monitoring radiopaque renal calculi ○ Colonic transit studies ■ Radiopaque markers ingested, time to exit bowel is monitored by AXR. ● Negatives ○ Ionising radiation ■ Pregnancy ○ Limited use ■ Less sensitive and specific than abdominal CT ○ Huge radiation dose - up to 35x that of CXR! ● Positives ○ Rapid, accessibleAXRAXR Annotated ● Large bowel in red ○ Large diameter ○ More peripheral ○ Sections ■ Ascending (pink arrow) ■ Transverse (orange arrow) ■ Descending (yellow arrow) ■ Sigmoid (blue arrow) ○ Flexures ■ Hepatic (green arrow) ■ Splenic (purple arrow) ● Small bowel (not annotated) ○ Central ○ Smaller diameterAbdominal CT ● Indications ○ Trauma ○ Cancer ○ Abdominal aortic aneurysms ○ Infection and inflammation ■ Appendicitis, pyelonephritis, abscesses ○ Guided biopsy ● Negatives: ○ Ionising radiation ● Positives: ○ Relatively quick and accessible ○ Can be taken with oral and/or IV contrast.CT Abdomen Axial CT Abdomen: Annotated 1. Red: Gallbladder 2. Orange: Stomach/bowel 3. Yellow: Pancreas a. Sausage like 4. Pink: Aorta 5. D. Green: Spine 6. L. Green: Spleen 7. L. Blue: Kidneys 8. Purple: LiverCT Abdomen: CoronalCT Abdomen Coronal: Annotated Case 1 ● 12M with 4/24 RIF pain, fever, and anorexia. ● Tender ++ in RIF, Rovsing’s sign positive. ● What is the diagnosis? ○ A: Diverticulitis ○ B: Appendicitis ○ C: Constipation ○ D: UTI RIF: Right Iliac Fossa GI: Appendicitis ● Presents with central abdominal pain that migrates to the RIF. ○ Associated Sx: fever, anorexia ● Rovsing’s sign ○ Palpation of LIF → pain in RIF ● Findings on imaging ○ Faecolith ■ Bright white dot ○ Fat stranding ■ Notice the area around the appendix is blurry and grey. ■ Indicates inflammation around a structure. RIF: Right Iliac Fossa LIF: Left Iliac FossaUpper GI AnatomyUpper GI: Celiac Trunk ● Celiac artery arises from the aorta. ● Its branches supply the liver, stomach, abdominal oesophagus, spleen, and superior half of duodenum and pancreas.Celiac Trunk 6 2 1. Splenic 2. Left gastric 3. Gastroduodenal 4 4. Hepatic 5 5. Right Hepatic 1 6. Left Hepatic 3 Anatomical variants exist but this is the ‘standard’ anatomy.Barium Swallow ● What is it? ○ Fluoroscopy ■ Barium/contrast is swallowed and continuous or pulsed X-ray beam is used. ■ Lots of images taken to assess movement. ● Similar to stop motion animation. ● Indications ○ Evaluation of pharynx, oesophagus, and proximal stomach ○ Dysphagia ○ Hiatus hernia ○ Persistent vomiting ● Contraindications to barium (use water soluble contrast instead) ○ Suspected perforation ○ Postoperative assessment for leak ● Things to note: ○ Largely replaced by upper GI endoscopy.GI: Case ● 70F with 3/12 dysphagia and regurgitation of food. ● What radiological sign is present in this image? ○ A: Veil sign ○ B: Steeple sign ○ C: Bird’s beak sign ○ D: Sail signAchalasia ● Barium swallow ○ Examination of upper GI ● Achalasia ○ Failure of smooth muscle to relax, causes lower oesophageal sphincter to remain constricted. ○ Bird’s beak sign ○ Tapering at lower oesophageal sphincter and narrowing at gastro-oesophageal junction ● Other signs mentioned in the MCQ ○ Veil sign: Left upper lobe lung collapse ○ Steeple sign: croup ○ Sail sign: Left lower lobe lung collapseGI: Case ● 60M with 4/12 of burning pain in throat. ● What is the diagnosis? ○ A: Hiatus hernia ○ B: Stomach cancer ○ C: Oesophageal stricture ○ D: Achalasia Lateral APGI: Hiatus Hernia ● Protrusion of part of stomach through diaphragm and into thoracic cavity. ○ Red circle: area where stomach passes through diaphragm. ● Can be asymptomatic or present with heartburn, dysphagia, hoarseness. ● Obesity and increased age are risk factors. GI: Case ● 30F presenting with chronic epigastric abdominal pain. ● Where is the abnormality? ○ A: Stomach ○ B: Liver ○ C: Pancreas ○ D: KidneyGI: Chronic Pancreatitis ● Chronic pancreatitis can lead to calcification of the pancreas. ○ Often due to chronic alcohol use. ● Pancreas looks like a sausage on CT (in my opinion).Lower GI AnatomyCT Colonography ● AKA virtual colonoscopy ○ Minimally invasive technique used for colorectal cancer screening. ○ Often used if colonoscopy is unsuccessful, contraindicated, or refused. ○ 3D image created. ● Benefits ○ Less invasive, fewer complications ○ Can detect extracolonic pathology ● Negatives ○ Cannot biopsy at time of procedure ○ Ionising radiation ○ Faecal matter can mimic masses Lower GI: Case ● 70F, 3/12 abdominal pain and constipation. ● Colonoscopy not tolerated. ● CT colon is performed, what is the diagnosis? ○ A: Colon cancer ○ B: Ulcerative colitis ○ C: Coeliac disease ○ D: Diverticular diseaseLower GI: Diverticular Disease ● Diverticulosis ○ Presence of noninflamed outpouchings called diverticula ■ Most commonly in sigmoid ○ Often asymptomatic ● Diverticulitis ○ Inflamed diverticulum ○ 4% of those with diverticulosis develop diverticulitis ● Barium enema (bottom left image) ○ Similar to barium swallow ○ Largely replaced by CTBiliary Anatomy MRCP L + R hepatic common→ hepatic → common bile ● Magnetic Resonance CholangioPancreatography ● Indications ○ Visualize intra and extrahepatic biliary tree and pancreatic ductal system ○ Choldocholithiasis ■ Gallstones in common bile duct. Pancreatic ○ Chronic pancreatitis Gallbladder duct ○ Pancreatic cystic lesions ● Things to note Oddi goingof ○ No contrast required! into duodenum ■ Through the magic of MRI the fluid in the biliary and pancreatic ducts is used as an intrinsic contrast medium. ○ Often used instead of ERCP - reduces morbidity and mortality in high risk patients. ERCP: Endoscopic Retrograde Cholangiopancreatography (we will discuss this in a few slides!)Biliary Anatomy https://www.bmj.com/content/345/b mj.e7805 Biliary Anatomy: Annotated ● A: Right hepatic duct ● B: Left hepatic duct ● C: Common hepatic duct ● D: Common bile duct ○ Abnormally dilated in this image! ● E: Pancreatic duct ● F: Second part of duodenum ● G: Gallbladder ● H: Cystic duct ● Yellow: Liver ● Green: GB + bile ducts ● Red: Duodenum ● Blue: PancreasGI: Case ● 40F with 3/12 RUQ pain after eating. ● Where is the abnormality? ○ A: Gallbladder ○ B: Liver ○ C: Small bowel ○ D: Stomach RUQ: Right Upper QuadrantGI: Gallstones ● Cholelithiasis: ○ Gallstones in the gallbladder ○ Can be multiple (like the AXR) or single and large (like the CT) ● Choledocholithiasis ○ Gallstones within common bile duct.ERCP ● Endoscopic retrograde cholangiopancreatography ○ Procedure involving endoscope passed down into duodenum. Wire is passed through sphincter of Oddi into CBD. Contrast has been injected and X-ray taken. ○ Usually performed by gastroenterologists or general surgeons rather than radiologists. ● Indications ○ Diagnostic ■ Evaluation of biliary tree and pancreatic ducts. ○ Therapeutic ■ Sphincterotomy ■ Biliary stenting ■ Bile duct stones removal ● Contraindications ○ Unstable patient ○ Coagulopathy ● Complications ○ Pancreatitis ○ Haemorrhage ○ Perforation ○ Infection (cholangitis)Renal AnatomyCT KUB ● Non-contrast CT specifically for kidneys, ureters, and bladder. ● Indications ○ Urolithiasis ■ Initial imaging in emergency setting ○ Haematuria ○ Flank pain ● Findings ○ Radiopaque stones ■ Size can guide management ○ Sequelae of stones ■ Obstruction ● Hydronephrosis ● Dilatation of ureter ■ InfectionRenal Pathology ● 30M with left sided back pain and intermittent haematuria. ● What is the diagnosis? ○ A: renal cancer ○ B: UTI ○ C: Renal calculus ○ D: Bladder tumourRenal: Staghorn Calculus ● Branching kidney stone.Ultrasound ● Indications ○ Hydronephrosis assessment ■ ?obstruction ○ Cystic kidney disease ○ Monitoring of chronic kidney disease ● Things to note: ○ Does not use ionising radiation ○ User dependentRenal: Pathology ● 70F with known bladder tumour that is obstructing her ureterovesical junction. ● An US of her kidney shows what? ○ A: Normal finding ○ B: Hydronephrosis ○ C: Metastatic disease ○ D: StoneRenal: Pathology ● Hydronephrosis is dilatation of the urinary collecting system of the kidney. ● Often due to obstruction e.g. tumours, stones, enlarged prostateRenal: Pathology (tricky!!) ● 60M presenting with frank haematuria. Diagnosed with ‘nutcracker syndrome’. ● A key vessel (circled in red) is being squished. What is the name of this vessel? A: Right renal artery B: Left renal artery C: Right renal vein D: Left renal vein GI: Nutcracker Syndrome ● A complicated case but it demonstrates anatomy well! ● Nutcracker syndrome ○ Left renal vein is squished between the SMA and the aorta as the SMA branches off ■ (although other variations exist). ○ → renal venous hypertension → bursting of thin walled veins in kidneys → haematuria. ○ Left gonadal vein drains into the left renal vein and is affected by renal venous hypertension ■ → tortuosity of the left gonadal vein. ■ The right gonadal vein usually SMA: Superior drains directly into the IVC. Mesenteric ArteryGenitourinary AnatomyGU: Case 1 ● 70M presenting with 3/12 haematuria and weight loss. ● What is the diagnosis? ○ A: Stone ○ B: Bladder tumour ○ C: Prostate disease ○ D: UTIGU: Bladder tumourCystography ● Fluoroscopic study that images the bladder. ○ Similar to a voiding cystourethrogram which images the urethra. ● A catheter is inserted and water soluble contrast is injected through the catheter and into the bladder. An X-ray is taken. ● Indications ○ Bladder leak following trauma ○ Dysfunctional voiding ○ Bladder outlet obstruction ○ Haematuria ○ Congenital abnormalities of the GU tract.GU: Case 2 ● 30F with chronic kidney disease. ● This is cystography. ● Abnormal: yes or no?GU: Vesicoureteric Reflux ● Vesicoureteric reflux bilaterally ○ Contrast should not enter ureters. ■ Indicates urine is going the wrong way up a one way street (the ureters) ○ Often occurs in children. ○ Urine backflow into ureters and kidneys → renal scarring → CKD ● Other findings include a small bladderGU: Vesicoureteric Reflux ● Reflux nephropathy can be monitored with nuclear medicine scans. ● DMSA is a radioactive substance taken up by the kidneys. ○ Areas of less uptake represent renal scarring (non-functioning nephrons) ○ Can also be used to check kidney position, size, presence of duplex kidneyConclusion ● Lots of imaging techniques exist ○ Know the basics of XR, CT, MRI, US ■ Are they good for bones, soft tissue? ■ Ionising radiation? ○ Know some of the more special tests e.g. barium swallow/enema, nuclear medicine scans, MRCP/ERCP ■ Consider if they are good tests for anatomy or physiology (or both) ● One of the best ways to learn anatomy is by comparing normal with the abnormal! ○ Clinical scenarios help to put anatomy into context and make it more memorable (and fun). ● The key to imaging is exposure ○ Radiology masterclass (beginner interpretation), MRI master (scrollable scans with labelled anatomy), Radiopedia (more advanced) ○ Use PACS on placement/ask Drs to show you scansQuestions/Feedback Feedback Form
