Radiology References

C

• Normal Caecum Size on Radiography and CT: <9 cm

  The normal caecum measures less than 9 cm in anteroposterior diameter on radiography and CT; exceeding this threshold indicates clinically significant distension.

• Normal Calcaneal Pitch Angle Size on Radiography

  Normal calcaneal pitch on lateral foot radiography ranges from 10–30°, a key measurement for evaluating flatfoot and cavus deformities.

• Normal Calcaneal-Fifth Metatarsal Angle Size on Radiography

  Reference values for the normal calcaneal–fifth metatarsal angle on AP foot radiography across pediatric age groups, from newborn to age 9.

• Normal Calcaneus–2nd Metatarsal Angle Size on Radiography

  Normal calcaneus–2nd metatarsal angle on AP radiography measures 12–18°, a key landmark for assessing hindfoot and forefoot alignment.

• Normal Capitolunate Angle Size on Radiography

  Normal capitolunate angle on lateral wrist radiography ranges from -15° to 15°, a key measure for detecting carpal instability.

• Normal Cardiac Diameter Size on Chest Radiography

  Reference values for normal cardiac diameter on chest radiography in adults and children aged 4–16, including transverse and posteroanterior measurements.

• Normal Cardiothoracic Index Size on Radiography

  Reference values for the normal cardiothoracic index on chest radiography across all age groups, from neonates to adults.

• Normal Carina Angle Size on Chest Radiography

  The normal carina angle on posteroanterior chest radiography measures 40–80°, with widening suggesting left atrial or subcarinal pathology.

• Normal Carpometacarpal Joint Space Size on Radiography

  Normal carpometacarpal joint space measures 1–2 mm on radiography; learn measurement technique, clinical significance, and common pathology.

• Normal Caton-Deschamps Index Size on Radiography

  Normal Caton-Deschamps Index on lateral knee radiography ranges from 0.6 to 1.2, guiding diagnosis of patella alta and baja.

• Normal Central Venous Catheter Tip Position on Radiography

  Normal central venous catheter tip position on chest radiography is at the superior vena cava–right atrium junction, as per Critical Care Radiology guidelines.

• Normal Cephalic Index Size on Obstetric Ultrasound

  The normal fetal cephalic index ranges from 75–85 on obstetric ultrasound, helping detect head shape abnormalities that affect biometric accuracy.

• Normal Cerebellar Tonsil Position Size on CT and MRI

  Normal cerebellar tonsils sit less than 3 mm below the foramen magnum on MRI and CT — a key threshold for diagnosing Chiari malformation.

• Normal Cerebral Artery Diameter on Angiography

  Reference values for normal cerebral artery diameter on angiography, including anterior, middle, and posterior cerebral arteries in adults.

• Normal Cervical Basal Angle Size on X-ray, CT & MRI

  Normal cervical basal angle ranges from 125–143° on lateral imaging; values outside this range may indicate platybasia or craniovertebral junction anomalies.

• Normal Cervical Interspinous Distance Size on Radiography, CT, MRI

  Normal cervical interspinous distance should be less than 1.5× the mean interspinous distance — a key radiologic marker for ligamentous injury.

• Normal Cervical Length in Pregnancy: Ultrasound Reference

  Normal cervical length before 36 weeks gestation is greater than 3 cm on ultrasound; shorter measurements indicate increased risk of preterm labor.

• Normal Cervical Lymph Node Size on CT, MRI & Ultrasound

  Reference thresholds for pathological cervical lymph node enlargement by level on CT, MRI, and ultrasound in head and neck imaging.

• Normal Cervical Lymph Node Size on Ultrasound, CT & MRI

  Learn the pathological enlargement thresholds for cervical lymph nodes by level on ultrasound, CT, and MRI, based on evidence-based radiology criteria.

• Normal Cervical Posterior Line Alignment on X-ray, CT, MRI

  Normal cervical posterior line displacement is less than 2 mm on lateral radiography, CT, and MRI — a key marker for detecting instability.

• Normal Cervical Wedge Compression Fracture Size on X-Ray & CT

  Normal cervical wedge compression fracture threshold: posterior-to-anterior vertebral height difference less than 3 mm on lateral radiography and CT.

• Normal CFL/ATFL Angle Size on MRI: Reference Values

  The normal CFL/ATFL angle on MRI ranges from 70° to 140°, a key measurement for assessing lateral ankle ligament anatomy and injury.

• Normal Chamay's Translation Index Size on Radiography

  Normal Chamay's Translation index on posteroanterior wrist radiography ranges from 0.25 to 0.31, a key metric for assessing carpal ulnar translation.

• Normal Chamberlain's Line Measurement: X-Ray, CT & MRI

  Normal Chamberlain's line measures less than 3 mm odontoid tip projection on lateral radiography, CT, and MRI for craniovertebral junction assessment.

• Normal Cochlear Bud Size on CT and MRI: Key Reference

  Normal cochlear bud diameter measures 1–3 mm on axial CT and MRI, a critical landmark when evaluating congenital sensorineural hearing loss in children.

• Normal Colon Diameter Size on Radiography and CT

  Normal colonic diameter is less than 6 cm on radiography and CT; values above this threshold indicate significant dilation requiring prompt evaluation.

• Normal Colon Wall Thickness on Ultrasound and CT

  Normal colon wall thickness measures less than 3–5 mm on CT and ultrasound; values above this threshold suggest pathology requiring further evaluation.

• Normal Common Bile Duct Diameter by Age: Ultrasound

  Reference values for normal common bile duct maximal diameter on ultrasound in pediatric patients, from neonates through adolescence.

• Normal Common Bile Duct Diameter on Cholangiography

  Reference values for normal common bile duct maximal diameter on cholangiography in children aged 0–14 years, based on Witcombe & Cremin 1978.

• Normal Common Bile Duct Size on CT, MRI & Ultrasound

  Normal common bile duct diameter is <6 mm without cholecystectomy and <10 mm post-cholecystectomy on CT, MRI, and ultrasound.