Radiology

A

• Acute Cholecystitis - Imaging with Ultrasound and HIDA

  Ultrasound is the first imaging test for suspected acute cholecystitis because it detects gallstones, gallbladder distention, wall changes, pericholecystic fluid, and a sonographic Murphy sign without radiation. If ultrasound is equivocal but clinical suspicion remains substantial, hepatobiliary scintigraphy is highly sensitive for cystic duct obstruction, while CT or MRI helps evaluate complications and alternative diagnoses.
• Acute Ischemic Stroke - Noncontrast CT, CTA, and CT Perfusion

  Acute ischemic stroke imaging begins with immediate noncontrast head CT to exclude hemorrhage and identify major established infarction. CTA rapidly evaluates intracranial and cervical large-vessel occlusion, while CT perfusion or MRI can help select patients for thrombectomy in extended or uncertain time windows. Imaging must support reperfusion decisions without delaying eligible thrombolysis.
• Adnexal Mass - Ultrasound O RADS Based Management

  O-RADS ultrasound standardizes adnexal lesion description, malignancy risk, and management. Transvaginal and transabdominal ultrasound characterize lesion size, cystic versus solid components, wall and septal features, papillary projections, vascularity, and ascites. Management depends on O-RADS category, menopausal status, symptoms, lesion size, and whether an ultrasound specialist or MRI is needed for further characterization.
• Adult Minor Head Injury - CT Decision Rules

  Adult minor head injury imaging should be selective. In neurologically stable adults with blunt head trauma, validated decision tools such as the Canadian CT Head Rule can identify patients who need noncontrast head CT while reducing unnecessary radiation. Anticoagulation, persistent neurologic symptoms, age, mechanism, and signs of skull fracture modify the threshold, and a normal CT does not eliminate the need for concussion instructions.
• Appendicitis - Imaging in Adults and Children

  Imaging for suspected appendicitis is age and context dependent. In nonpregnant adults, contrast-enhanced CT is highly accurate and often first line. In children and many pregnant patients, graded-compression ultrasound is preferred initially, with MRI or CT used when ultrasound is nondiagnostic and clinical concern persists.

B

• Breast Imaging - BI RADS Assessment and Recommendations

  BI-RADS standardizes breast imaging terminology, final assessment, and management across mammography, ultrasound, MRI, and now current ACR breast-imaging practice. The category is not simply a malignancy score: BI-RADS 0 means more imaging is needed, 1 and 2 are negative or benign, 3 is probably benign with short-interval follow-up, and 4 or 5 generally require tissue diagnosis.

C

• Cervical Spine Trauma - Imaging with NEXUS or Canadian Rules

  Use NEXUS or Canadian C spine rule to select patients for imaging, prefer CT over plain radiographs in adults, and ensure full coverage through cervicothoracic junction.
• CT Perfusion in Stroke — Basics for Clinicians

  CTP estimates infarct core vs penumbra to guide thrombectomy and thrombolysis beyond standard windows; interpret in context with CTA/NCCT and clinical exam.

H

• Hepatocellular Carcinoma - Imaging and LI RADS Surveillance

  LI-RADS standardizes liver imaging in patients at high risk for hepatocellular carcinoma. Surveillance is generally performed every 6 months with ultrasound and AFP in appropriate cirrhosis and hepatitis B populations, while diagnostic multiphasic CT or MRI classifies observations by major features such as arterial-phase hyperenhancement, washout, enhancing capsule, size, and threshold growth.

I

• Incidental Pulmonary Nodule - CT Follow Up per Fleischner

  Incidental pulmonary nodules should be managed by nodule size, morphology, number, and patient cancer risk rather than by a one-size-fits-all repeat CT schedule. Fleischner Society recommendations apply to incidentally detected nodules in adults outside lung-cancer screening and exclude important groups such as patients younger than 35, known cancer, or significant immunocompromise.
• Iodinated Contrast Allergy - Premedication and Alternatives

  For prior immediate contrast reactions, use shared decision making, consider noncontrast or alternate imaging, and if proceeding use an evidence based premedication protocol with emergency readiness.

L

• LI‑RADS — HCC Imaging & Reporting

  Standardizes imaging for HCC in high‑risk patients using LR‑1 to LR‑5, LR‑M, LR‑TIV. Major features include arterial phase hyperenhancement, washout, capsule, size, and growth.
• Lung‑RADS — Low‑Dose CT Screening Interpretation

  Use ACR Lung-RADS v2022 to standardize low-dose CT lung cancer screening findings and management. Assign the category from nodule type, size or volume, growth, and suspicious features; distinguish screening findings from symptoms that require diagnostic evaluation, use short-interval LDCT for selected indeterminate or inflammatory findings, and return clearly benign or stable examinations to annual screening.

M

• MRI Conditional Implants - Safety Screening and Protocol

  An MR Conditional implant is safe only under the specific conditions listed by the manufacturer. The label does not mean the device is universally MRI safe. Before scanning, identify the exact implant, verify field strength, spatial-gradient, RF power, coil, positioning, and programming requirements, and perform a documented final safety check. Unknown implants require risk assessment rather than assumption.
• MRI Safety — Implants & Devices

  MRI safety depends on verifying the patient, implant or device, field strength, scanner conditions, and the exact MR-conditional labeling before entering the magnet environment. Use the ACR 2026 MR Safety framework, perform a documented final safety check, never infer device compatibility from appearance or prior uneventful MRI, and escalate uncertain implants or abandoned leads to formal risk assessment rather than improvising at the scanner.
• MSK Ultrasound — Rotator Cuff & Achilles Tendon

  Point‑of‑care and diagnostic MSK US for rotator cuff and Achilles: standardized scanning planes, dynamic maneuvers, and avoidance of anisotropy improve accuracy.

O

• O‑RADS — Ovarian/Adnexal US Risk Stratification

  Use O-RADS US v2022 to describe ovarian and adnexal lesions with standardized lexicon terms and assign a malignancy-risk category linked to management. First determine whether the lesion is physiologic or classic benign, then characterize cystic versus solid components, septations, papillary projections, vascularity, and ascites; when ultrasound remains indeterminate, MRI or specialist evaluation can improve specificity.

P

• Pancreatic Cyst - Imaging Reporting and Management

  Pancreatic cyst management depends on cyst type, size, main-duct involvement, mural nodules or solid components, symptoms, growth, and patient fitness for surgery. MRI/MRCP is often the preferred surveillance modality, while EUS with fluid analysis or biopsy is used when imaging shows concerning features or the diagnosis remains uncertain.
• Pediatric Imaging — Radiation Dose Considerations

  Apply ALARA: justify imaging, prefer US/MRI when appropriate, and tailor CT protocols by weight/size to minimize radiation while preserving diagnostic quality.
• PI‑RADS — Prostate MRI Basics

  PI-RADS v2.1 standardizes acquisition and interpretation of prostate MRI for clinically significant prostate cancer. Score lesions from 1 to 5 using zone-specific dominant sequences, integrate diffusion-weighted imaging, T2-weighted imaging, and dynamic contrast enhancement appropriately, report lesion location and size, and interpret the score together with PSA density, prior biopsy history, examination, and patient risk rather than treating PI-RADS as a stand-alone diagnosis.
• POCUS Aorta — AAA Screening & Measurement

  Bedside US screens for AAA ≥3.0 cm; measure outer‑to‑outer wall in AP dimension; scan diaphragm to bifurcation; recognize pitfalls.
• POCUS DVT — Compression Technique & Pitfalls

  Two‑ or three‑point compression ultrasound detects proximal DVT at the CFV, FV, and popliteal veins; know pitfalls and when to obtain full duplex.
• Post Contrast AKI - Risk Assessment and Hydration

  Modern evidence distinguishes contrast-associated AKI, which occurs after contrast exposure, from true contrast-induced AKI caused by the contrast itself. The nephrotoxic risk of IV iodinated contrast has historically been overstated. Preventive IV isotonic fluid is mainly reserved for patients with acute kidney injury or severe CKD, particularly eGFR below 30, when contrast is necessary and volume status permits.
• Pulmonary Embolism - Imaging Algorithm with CTPA or VQ

  Pulmonary embolism imaging begins with pretest probability, not with CT. Low-risk patients may need no testing after a validated rule-out strategy; others undergo D-dimer before imaging when appropriate. CTPA is the standard anatomic test, while ventilation-perfusion imaging is especially useful when iodinated contrast is undesirable or chest radiography is near normal.

R

• Renal Colic - Ultrasound First, CT When Necessary

  Renal colic imaging should balance diagnostic certainty with cumulative radiation. Ultrasound can identify hydronephrosis and alternative urinary pathology without radiation and is a reasonable first study in many younger patients, pregnancy, and recurrent uncomplicated stone formers. Noncontrast CT remains the most accurate test and is preferred when the diagnosis is uncertain, complications are possible, or an alternative dangerous process must be excluded.

S

• Superior Vena Cava Syndrome — Oncologic Emergency, Stenting, and Tissue Diagnosis

  Dyspnea, facial and upper‑extremity swelling, and venous distension from malignant obstruction are classic. Assess airway and hemodynamics; obtain tissue diagnosis before radiation when feasible. Endovascular stenting offers rapid relief; adjunct steroids are disease‑specific (e.g., lymphoma).
• Suspected Osteomyelitis - Imaging with MRI Preferred

  MRI is the preferred advanced imaging test for suspected osteomyelitis because marrow edema, cortical involvement, abscess, and adjacent soft-tissue disease can be detected earlier than on radiographs. Plain radiographs remain the usual first study, and imaging must be interpreted with clinical findings because marrow edema after surgery, trauma, neuropathic arthropathy, and inflammatory disease can mimic infection.

T

• Thyroid Nodule - Ultrasound TI RADS Based Management

  ACR TI-RADS converts five thyroid-ultrasound feature groups into a point score that estimates malignancy risk and sets size thresholds for FNA or surveillance. The system reduces unnecessary biopsy by separating suspicious appearance from whether a nodule is large enough to sample. Clinical context, PET avidity, suspicious lymph nodes, prior neck radiation, and life expectancy can appropriately override a routine TI-RADS recommendation.