Contrast and Radiological Procedures Practice Questions

Q: What is an absolute contraindication for intravenous pyelography (IVP)?

Allergy to the contrast agent. **Explanation:** Intravenous Pyelography (IVP) involves the systemic administration of iodinated contrast media to visualize the urinary tract. **1. Why "Allergy to the contrast agent" is correct:** A documented history of a severe or anaphylactoid reaction to iodinated contrast is the only **absolute contraindication**. Since IVP requires intravenous injection, re-exposure can trigger life-threatening anaphylaxis, angioedema, or cardiac arrest. While mild reactions can sometimes be managed with premedication (steroids/antihistamines), a true systemic allergy makes the procedure unsafe. **2. Analysis of Incorrect Options:** * **Multiple Myeloma:** This is a **relative contraindication**. In these patients, contrast can precipitate with Bence-Jones proteins in the renal tubules, leading to acute renal failure. However, the procedure can be performed if the patient is aggressively hydrated. * **Blood Urea > 200 mg/dL:** This indicates severe renal failure. It is a **relative contraindication** because the kidneys cannot concentrate the contrast, leading to poor visualization and a high risk of Contrast-Induced Nephropathy (CIN). * **Renal Tumor:** This is actually an **indication** for IVP (to check for filling defects or distortion of the calyces), not a contraindication. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard:** For most renal pathologies (stones, trauma, tumors), **NCCT (Non-contrast CT) KUB** has replaced IVP as the investigation of choice. * **Metformin:** Patients taking Metformin should ideally stop the drug 48 hours after contrast administration to avoid lactic acidosis, especially if renal function is impaired. * **Best Indicator of Renal Function:** Serum Creatinine and eGFR are more reliable than Blood Urea before administering contrast.

Q: Which one of the following contrast media is used for intravenous pyelography (IVP)?

Sodium diatrizoate (Hypaque). **Explanation:** Intravenous Pyelography (IVP), also known as Intravenous Urography (IVU), requires a water-soluble, iodinated contrast medium that is excreted primarily by glomerular filtration in the kidneys. **Why Sodium Diatrizoate (Hypaque) is correct:** Sodium diatrizoate is a high-osmolar ionic contrast medium (HOCM). It is the classic choice for IVP because the sodium salt provides a higher concentration of iodine per molecule compared to meglumine salts. This results in better opacification of the renal parenchyma (nephrogram phase) and the collecting system (pyelogram phase), which is essential for visualizing the anatomy of the ureters and bladder. **Analysis of Incorrect Options:** * **A. Lipiodol:** This is an oil-based contrast medium. It is strictly contraindicated for intravenous use as it can cause fat embolism. It is used for lymphangiography or HSG. * **B. Diatrizoate:** While technically correct as a class, "Sodium diatrizoate" is the specific formulation preferred for urinary tract opacification. * **D. Iothalamate (Conray-420):** While also an ionic contrast, Conray-420 has a very high iodine concentration (420 mg/mL) and is more commonly used for angiography or CT rather than routine IVP, where lower concentrations are often sufficient and safer. **High-Yield Clinical Pearls for NEET-PG:** * **Contrast Type:** Modern practice has shifted toward **Non-Ionic Low-Osmolar Contrast Media (LOCM)** like Iohexol or Iopamidol to reduce the risk of anaphylactoid reactions and Contrast-Induced Nephropathy (CIN). * **Preparation:** Patients must be screened for serum creatinine levels (normal <1.5 mg/dL) before IVP. * **Contraindications:** Absolute contraindications include history of severe reaction to iodine and anuria. * **Sequence:** The **Nephrogram phase** occurs within 1 minute, while the **Pyelogram phase** (filling of calyces) is best seen at 5–10 minutes.

Q: While taking the bitewing film, what should be the direction and angulation of the central ray?

10° above the horizontal plane. **Explanation:** The **Bitewing radiograph** is a specialized intraoral technique primarily used to detect interproximal caries and evaluate the height of the alveolar bone crest. **Why 10° above the horizontal plane?** In the bitewing technique, the film is held in place by the patient biting on a "tab." Due to the anatomical curvature of the palate and the slight lingual tilt of the maxillary teeth, the film packet often assumes a slightly slanted position rather than being perfectly vertical. To compensate for this slight palatal inclination and to ensure the X-ray beam passes directly through the interproximal spaces without overlapping the cusps, a **vertical angulation of +10°** (pointing downwards from above the horizontal plane) is required. This "positive" angulation results in a dimensionally accurate representation of both maxillary and mandibular crowns. **Analysis of Incorrect Options:** * **Option A (10° below):** This is "negative" angulation. Using negative angulation would cause elongation of the maxillary teeth and foreshortening of the mandibular teeth, obscuring the interproximal areas. * **Options C & D (10° right/left):** These refer to horizontal angulation. Horizontal angulation must be directed specifically through the contact points of the teeth being imaged (usually perpendicular to the arch) to avoid "overlapping" of proximal surfaces. It is not fixed at 10°. **High-Yield Clinical Pearls for NEET-PG:** * **Vertical Angulation:** +10° is the standard for bitewings. * **Indications:** Best for **Interproximal Caries** (earliest detection) and **Alveolar Crestal Bone** height (periodontal status). * **Common Error:** Incorrect horizontal angulation leads to **overlapping contacts**, making the radiograph non-diagnostic for caries. * **Comparison:** Unlike periapical X-rays, bitewings show the crowns of both upper and lower teeth on a single film.

Q: In phlebography, dye is injected into which of the following veins?

Dorsal metatarsal vein. **Explanation:** **Phlebography (Venography)** is the gold standard (though now largely replaced by Doppler ultrasound) for visualizing the deep venous system of the lower limb to detect Deep Vein Thrombosis (DVT). **Why the Dorsal Metatarsal Vein is Correct:** To visualize the entire deep venous system of the leg, the contrast medium must be injected into a **superficial vein as far distal as possible**. The **dorsal metatarsal vein** (or a vein on the dorsum of the foot) is the preferred site. A tourniquet is applied at the ankle to occlude the superficial veins; this forces the injected contrast from the superficial system into the **deep venous system** via the perforating veins. This ensures the deep veins (popliteal, femoral, and iliac) are opacified against the direction of gravity. **Analysis of Incorrect Options:** * **Anterior Tibial Vein:** This is a deep vein. Injecting directly into a deep vein is technically difficult, invasive, and defeats the purpose of using the physiological flow from superficial to deep systems. * **Great and Short Saphenous Veins:** While these are superficial veins, they are more proximal than the dorsal foot veins. Injecting here might bypass the distal deep veins, leading to an incomplete study of the calf veins where many thrombi originate. **High-Yield Clinical Pearls for NEET-PG:** * **Contrast Agent:** Low-osmolar contrast media (LOCM) are preferred to reduce the risk of post-venographic phlebitis. * **Gold Standard:** While Phlebography is the definitive "Gold Standard" for DVT, **Duplex Ultrasound** is the "Initial Investigation of Choice" due to its non-invasive nature. * **Filling Defect:** The hallmark of DVT on phlebography is a persistent, well-defined **intraluminal filling defect**.

Q: What is the best diagnostic method for tracheo-oesophageal fistula?

Dianosil. **Explanation:** The primary concern when imaging a suspected **Tracheo-Oesophageal Fistula (TOF)** is the risk of contrast aspiration into the lungs. **Why Dianosil is the Correct Answer:** **Dianosil (Propyliodone)** is an oil-based, iodinated contrast medium. It was historically considered the "gold standard" for bronchography and TOF because it is relatively inert in the tracheobronchial tree. Unlike other agents, it does not cause significant pulmonary edema or chemical pneumonitis if aspirated. Its high viscosity also allows for better mucosal coating, making small fistulous tracts easier to visualize. **Analysis of Incorrect Options:** * **A. Barium Sulphate:** Absolutely contraindicated if a fistula is suspected. If aspirated, barium is not absorbed and causes a severe **foreign body granulomatous reaction** and permanent alveolar scarring. * **B. Conray 240 (Iothalamate):** This is an ionic, high-osmolar contrast medium (HOCM). If aspirated, its high osmolality draws fluid into the lungs, leading to severe **pulmonary edema**. * **D. Urograffin (Diatrizoate):** Similar to Conray, this is an ionic HOCM. It is highly irritant to the lungs and can be fatal if aspirated in large quantities. **NEET-PG High-Yield Pearls:** * **Modern Practice:** While Dianosil is the classic textbook answer, it has been largely discontinued in many regions. In modern clinical practice, **Non-ionic Low-Osmolar Contrast Media (LOCM)** like **Iohexol (Omnipaque)** are preferred due to lower toxicity. * **Water-Soluble Contrast:** Always the first choice for suspected perforations (e.g., Gastrografin), *except* when aspiration is a risk. * **TOF Presentation:** Most common type is **Type C** (85%): Proximal esophageal atresia with a distal fistula. * **VACTERL Association:** Always screen for Vertebral, Anal, Cardiac, TOF, Renal, and Limb anomalies.

Q: Pantomography is done for which of the following, except?

Transverse fracture of the Atlas. **Explanation:** **Pantomography**, commonly known as **Orthopantomogram (OPG)**, is a specialized panoramic dental X-ray that provides a wide-angle, two-dimensional view of the maxilla, mandible, and teeth. It utilizes the principle of **curved-plane tomography** to "flatten" the dental arches into a single image. **Why Option D is the correct answer:** The **Atlas (C1 vertebra)** is located at the base of the skull. A transverse fracture of the Atlas (such as a Jefferson fracture) requires specific views like the **Open-mouth Odontoid view** or a CT scan for accurate visualization. Pantomography is designed to focus on the curved anatomy of the jaws; the cervical spine is often blurred or obscured by the "ghost image" of the spine itself during the rotational movement of the OPG machine. **Analysis of Incorrect Options:** * **A & B (Dental Caries and Cysts):** OPG is a primary screening tool for evaluating the general health of the teeth, detecting extensive dental caries, and identifying odontogenic cysts or tumors within the jawbones. * **C (Temporomandibular Joint):** Pantomography is frequently used to assess the TMJ for bony ankylosis, condylar fractures, or degenerative changes, as it captures both joints in a single film. **High-Yield Clinical Pearls for NEET-PG:** * **Principle:** Pantomography uses the concept of a **focal trough** (a 3D curved zone where structures are clearly imaged). * **Best for:** Impacted third molars, orthodontic assessment, and mandibular fractures. * **Limitation:** It provides less detail than intraoral periapical (IOPA) radiographs for fine interproximal caries. * **Radiation:** It offers a lower radiation dose compared to a full-mouth series of intraoral X-rays.

Q: What is the most common complication of myelography?

Headache. **Explanation:** The most common complication of myelography is a **Post-Dural Puncture Headache (PDPH)**, occurring in approximately 10% to 30% of patients. **Why Headache is the Correct Answer:** Myelography involves a lumbar puncture to inject contrast media into the subarachnoid space. The headache is caused by the persistent leakage of Cerebrospinal Fluid (CSF) through the dural puncture site. This leads to low CSF pressure (intracranial hypotension), causing traction on pain-sensitive structures like the meninges and cranial nerves when the patient is upright. Characteristically, this headache is **positional**—it worsens when standing and improves when lying flat. **Analysis of Incorrect Options:** * **Allergic Reaction (A):** While possible with any iodinated contrast, the use of modern non-ionic, low-osmolar water-soluble contrast media (like Iohexol) has made systemic allergic reactions rare in myelography. * **Focal Neurological Deficit (C):** This is a very rare complication, usually resulting from direct needle trauma to nerve roots or a spinal hematoma. * **Arachnoiditis (D):** This was a significant concern in the past when oil-based contrast media (e.g., Pantopaque/Myodil) were used. With modern water-soluble contrast, the risk of chronic inflammation of the arachnoid membrane is negligible. **High-Yield Pearls for NEET-PG:** * **Contrast of Choice:** Non-ionic, water-soluble, low-osmolar contrast (e.g., **Iohexol/Omnipaque** or **Iopamidol**). * **Prevention of PDPH:** Use of small-gauge (22G or 25G) needles and "atraumatic" (pencil-point) needles significantly reduces the risk. * **Management:** Conservative treatment includes bed rest, aggressive hydration, and caffeine. For persistent cases, an **epidural blood patch** is the definitive treatment. * **Contraindication:** Never use ionic contrast (e.g., Diatrizoate) for myelography as it is neurotoxic and can cause fatal seizures.

Q: What is the investigation of choice to demonstrate vesicoureteral reflux?

Contrast MCU. **Explanation:** **Micturating Cystourethrogram (MCU)**, also known as Voiding Cystourethrogram (VCUG), is the **gold standard and investigation of choice** for diagnosing and grading Vesicoureteral Reflux (VUR). The procedure involves catheterizing the bladder, filling it with water-soluble contrast, and taking fluoroscopic images during the act of micturition. This allows for the dynamic visualization of the retrograde flow of urine into the ureters and the renal pelvis, which is essential for the International Grading of VUR (Grades I-V). **Analysis of Options:** * **Isotope Cystogram (RNC):** While highly sensitive and associated with lower radiation than MCU, it lacks anatomical detail. It is primarily used for **follow-up** of known VUR or screening siblings, rather than initial diagnosis and grading. * **Intravenous Pyelogram (IVP):** This is a functional study of the kidneys and collecting system. While it may show secondary signs (like dilated ureters), it is not sensitive enough to diagnose VUR and has been largely replaced by USG and CT. * **Cystoscopy:** This is an invasive endoscopic procedure used to visualize the bladder mucosa and ureteric orifices. It cannot demonstrate the dynamic reflux of urine. **High-Yield Pearls for NEET-PG:** * **Grading:** VUR is graded I (ureter only) to V (gross dilation/tortuosity with loss of papillary impressions). * **Initial Screening:** Ultrasound is often the first-line screening tool in children with UTI to look for hydronephrosis, but MCU is required for definitive diagnosis. * **Associated Condition:** Posterior Urethral Valves (PUV) are the most common cause of secondary VUR in male infants; MCU is the diagnostic test for PUV as well.

Q: In which of the following conditions is water-soluble contrast media used?

Perforation. **Explanation:** The primary reason for using water-soluble contrast media (such as **Gastrografin** or **Iohexol**) instead of Barium sulfate is the risk of **peritoneal or mediastinal contamination**. 1. **Why Perforation is Correct:** In cases of suspected gastrointestinal perforation, Barium sulfate is strictly contraindicated. If Barium leaks into the peritoneal or pleural cavity, it is not absorbed and can cause a severe, life-threatening **chemical peritonitis** or granulomatous reaction leading to extensive adhesions. Water-soluble contrast, however, is rapidly absorbed by the peritoneum and excreted by the kidneys, making it safe in these scenarios. 2. **Why Other Options are Incorrect:** * **Constipation:** Barium is often preferred for lower GI studies (Barium Enema) as it provides superior mucosal detail. In fact, water-soluble contrast can sometimes worsen dehydration in severely constipated patients due to its high osmolarity. * **Ileocecal Tuberculosis:** Diagnosis requires fine mucosal detail to identify ulcers or the "Goose-neck deformity." Barium provides the high-contrast resolution necessary for these morphological details. * **GERD:** Evaluation of reflux and esophageal motility (Barium Swallow) requires the high density and coating properties of Barium to visualize minor mucosal erosions or strictures. **High-Yield Clinical Pearls for NEET-PG:** * **Choice of Agent:** Gastrografin (high osmolar) is the standard water-soluble agent, but **non-ionic low-osmolar contrast (LOCM)** is preferred if there is a risk of **aspiration**, as Gastrografin can cause severe pulmonary edema. * **Therapeutic Use:** Gastrografin is used therapeutically in **Meconium Ileus** due to its hyperosmolar nature, which draws water into the bowel lumen. * **Golden Rule:** If perforation is suspected, start with water-soluble contrast. If no leak is found and more detail is needed, you may then proceed with Barium.

Q: Which X-ray view is used to visualize the supraorbital fissure?

Caldwell view. The **Caldwell view** (Occipitofrontal projection) is the correct answer because it is specifically designed to visualize the anterior facial skeleton and the orbits. ### Why Caldwell View is Correct In this projection, the patient’s forehead and nose touch the film, and the X-ray beam is angled **15 degrees caudally**. This specific angulation pushes the dense petrous ridges of the temporal bone down to the lower third of the orbits. This clears the visual field, allowing for an unobstructed view of the **superior orbital fissure (SOF)**, the frontal sinuses, the ethmoid sinuses, and the orbital rims. ### Explanation of Incorrect Options * **Towne’s View:** This is an AP axial projection (30-degree caudal angle) used primarily to visualize the **occipital bone**, the foramen magnum, and the zygomatic arches. It is the best view for the posterior cranial fossa. * **AP View:** A standard AP view of the skull causes the petrous pyramids to be superimposed directly over the orbits, obscuring the fine details of the supraorbital fissure. * **Nasal View:** This typically refers to a lateral or specialized tangential view focused on the nasal bones to detect fractures; it does not provide the depth or orientation required to see the orbital fissures. ### High-Yield Clinical Pearls for NEET-PG * **Water’s View (Occipitomental):** The best view for **Maxillary sinuses** and the orbital floor (Blow-out fractures). * **Submentovertex (SMV) View:** Best for the **Zygomatic arches** (Jug-handle view) and the base of the skull. * **Schuller’s View:** Used for the Mastoid air cells. * **Stenver’s View:** Used for the Petrous temporal bone and Internal Auditory Meatus (IAM).

Question 1

What is an absolute contraindication for intravenous pyelography (IVP)?

Accepted Answer

Allergy to the contrast agent

Answer

Multiple myeloma

Answer

Blood urea level greater than 200 mg/dL

Answer

Renal tumor

Question 2

Which one of the following contrast media is used for intravenous pyelography (IVP)?

Accepted Answer

Sodium diatrizoate (Hypaque)

Answer

Lipiodol

Answer

Diatrizoate

Answer

Iothalamate (Conray-420)

Question 3

While taking the bitewing film, what should be the direction and angulation of the central ray?

Accepted Answer

10° above the horizontal plane

Answer

10° below the horizontal plane

Answer

10° to the right

Answer

10° to the left

Question 4

In phlebography, dye is injected into which of the following veins?

Accepted Answer

Dorsal metatarsal vein

Answer

Anterior tibial vein

Answer

Great saphenous vein

Answer

Short saphenous vein

Question 5

What is the best diagnostic method for tracheo-oesophageal fistula?

Accepted Answer

Dianosil

Answer

Barium sulphate

Answer

Conray 240

Answer

Urograffin

Question 6

Pantomography is done for which of the following, except?

Accepted Answer

Transverse fracture of the Atlas

Answer

Dental caries

Answer

Dental cyst

Answer

Temporomandibular joint

Question 7

What is the most common complication of myelography?

Accepted Answer

Headache

Answer

Allergic reaction

Answer

Focal neurological deficit

Answer

Arachnoiditis

Question 8

What is the investigation of choice to demonstrate vesicoureteral reflux?

Accepted Answer

Contrast MCU

Answer

Isotope cystogram

Answer

IVP

Answer

Cystoscopy

Question 9

In which of the following conditions is water-soluble contrast media used?

Accepted Answer

Perforation

Answer

Constipation

Answer

Ileocecal tuberculosis

Answer

Gastroesophageal reflux disease (GERD)

Question 10

Which X-ray view is used to visualize the supraorbital fissure?

Accepted Answer

Caldwell view

Answer

Towne's view

Answer

AP view

Answer

Nasal view

Contrast and Radiological Procedures — MCQs

Contrast and Radiological Procedures — MCQs

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