Author: Logan Young

Do you wanna see a snowman? University of Mississippi neuroradiologist Charlotte S. Taylor, MD, illustrates a specific abnormality of the sella/suprasellar region in this ARRS Web Lecture—now available in your library.

Waist Deep: When viewing a coronal or sagittal MRI of a classic pituitary macroadenoma (PM), you’ll often spot a snowman-shaped, homogeneously enhancing mass. This characteristic shape occurs due to a sella mass that develops a suprasellar extension, creating a “waist” as it pushes upward. In these pronounced cases, the normal pituitary tissue is usually completely displaced or obscured. You may also notice local bony involvement, including erosions in the sphenoid sinus and clivus.

Hat Trick: As the tumor extends superiorly, it exerts mass effect on the optic chiasm. The chiasm can become so severely stretched that it is difficult to visualize directly—effectively forming a sadly stretched “hat” resting atop our snowman’s noggin.

If the optic chiasm is too stretched to be seen clearly, look for the anterior cerebral arteries (ACA) and the anterior communicating arteries (Acomms). Because these vessels supply perforators to the optic chiasm, they are physically tethered to it. As these vessels are displaced superiorly by the mass, you can use ACA/Acomms as a reliable surrogate for location.

What About BHA? By definition, a PM measures 10 mm or greater in size. The non-functional variants are the most common and typically present due to visual disturbances resulting from the suprasellar mass effect. Whereas rads have been taught that pituitary adenomas cause true bitemporal hemianopsia (BHA), complete BHA is exceedingly rare, occurring in less than 1% of patients. Instead, incomplete bitemporal or mixed visual field defects are the most common presentation, seen in about 42.6% of patients. Notably, these visual field defects typically only occur when the tumor displaces the optic pathway by 3 mm or more.

Surgical Insight: Treatment for these lesions is generally surgical—most frequently an endoscopic transsphenoidal approach—with the notable exception of prolactinomas, which are treated medically using dopamine agonists. For surgical candidates, preoperative MRI features can help predict procedural success. Results from AJR show tumors with macrocysts, macrohemorrhage, or enhanced diffusivity (ADC ratio > 1.1) are highly resectable via transsphenoidal approach. Conversely, solid tumors with restricted diffusion tend to have a higher reticulin content, making them more rigid and more likely to fail transsphenoidal resection, perhaps requiring transcranial surgery.

Surveilling a Nonresected PM: For conservative patient management, the debate remains. Some experts argue gadolinium-based contrast agents are essential to assess tumor invasiveness, detect solid components, and evaluate markers of aggressive proliferation. And others counter that an unenhanced coronal T2-weighted MRI is perfectly adequate for tracking dimensions and optic compression, allowing your patient to avoid the costs, discomfort, and long-term retention risks associated with IV contrast.

Budd-Chiari syndrome is a disorder of hepatic venous outflow obstruction involving the accessory hepatic veins, major hepatic veins, or the suprahepatic inferior vena cava. Clinically, patients present with abdominal pain, hepatomegaly, and ascites—manifestations of sinusoidal congestion and portal hypertension.

The pathophysiology is straightforward: impaired venous drainage leads to hepatic congestion, rising sinusoidal pressures, and progressive liver dysfunction. However, as  Baljendra S. Kapoor, MD, pointed out during this ARRS Quick Byte, the management algorithm is nuanced.

Baby Steps: Initial therapy is systemic anticoagulation. For patients with short-segment hepatic vein stenosis, balloon angioplasty with possible stenting is recommended, consistent with guidance from the American College of Gastroenterology.

When these approaches fail or are not feasible, the next-line intervention is Transjugular Intrahepatic Portosystemic Shunt (TIPS) placement. TIPS functions by creating a low-resistance channel between the portal and systemic venous systems, decompressing congested hepatic sinusoids and restoring effective outflow.

Recent Evidence: A meta-analysis of 1,395 patients published in JVIR demonstrated:

• 98.6% technical success
• 90.3% clinical success
• 0.5% TIPS-related mortality

These outcomes underscore both feasibility and safety. Much of the data derives from Asian cohorts, and randomized comparative trials remain limited, leaving questions about optimal patient selection and timing. Nonetheless, the existing evidence base supports TIPS as a highly effective salvage—and, in many cases, definitive—therapy.

Case in Point: A 44-year-old woman with prior cerebrovascular accidents and paroxysmal nocturnal hemoglobinuria presented with abdominal pain, nausea, and vomiting. CT demonstrated an enlarged, heterogeneous liver with markedly heterogeneous enhancement and small-volume ascites—classic features of hepatic venous outflow obstruction.

Ultrasound confirmed hepatic vein occlusion.

TIPS was successfully created, re-establishing outflow and decompressing the congested liver.

Clinical Inflection Point: Budd-Chiari management reflects a broader interventional principle…anticoagulate → recanalize, if possible → decompress, if necessary. For patients who fail medical therapy and angioplasty, TIPS is not merely palliative. It directly addresses the hemodynamic derangement driving symptoms and liver injury.

Bottom Line: Budd-Chiari syndrome is a vascular disorder with mechanical consequences. When hepatic venous obstruction persists despite anticoagulation and angioplasty, TIPS provides high technical success, strong clinical response rates, and low procedure-related mortality. In appropriately selected patients, decompression changes the trajectory of disease.

While ultrasound (US) remains the cornerstone of fetal screening due to its safety, real-time capabilities, and cost-effectiveness, occasionally, it meets its limits, too. In these instances, fetal MRI acts as a targeted problem-solving complement rather than a replacement, providing the clarity needed for high-stakes clinical decisions.

Safwan Halabi, MD, speaks with AJR Podcast Series host Raisa Amiruddin, MBBS, on techniques for detailed imaging of the developing fetus and the role of radiologists in the multidisciplinary fetal medicine team.

MRI Steps In: MRI is most frequently utilized when US raises questions that require deeper characterization in the following areas:

• CNS Anomalies—MRI excels at evaluating the fetal brain, offering superior soft tissue contrast to visualize intricate details of cortical development, the corpus callosum, and posterior fossa structures.
• Prognostic Quantification—For conditions like congenital diaphragmatic hernia, MRI provides precise measurements of fetal lung volume, which is a critical predictor of postnatal outcomes and candidacy for fetal surgery.
• Complex Fetal Masses—In cases of masses like sacrococcygeal teratomas, MRI clarifies the internal composition and relationship to adjacent structures, which is essential for surgical and delivery planning.

Technical Hurdles: One of MRI’s greatest strengths is its independence from the technical limitations that often challenge US. MRI quality is not degraded by:

• Fetal position or maternal body habitus
• Low levels of amniotic fluid (oligohydramnios)
• Maternal positioning, as mothers can often be adjusted within the scanner for comfort

Safety and Field Strength: Safety is a primary concern for expecting parents, of course. Routine fetal MRI uses no ionizing radiation and is performed without IV contrast, eliminating additional exposure concerns.

Fetus at gestational age of 13 weeks 0 days evaluated by MRI at 3T to characterize multiple congenital anomalies. Left, Sagittal 2D balanced SSFP image through entire fetus shows anterior abdominal wall defect with exteriorized liver (white arrow) and micrognathia (black arrow). Right, Coronal 2D balanced SSFP image through fetal face shows bilateral cleft lip and cleft palate (white arrows) and hypertelorism (black arrows). Additional anomalies depicted by this fetal MRI examination (not shown) included bilateral cerebral ventriculomegaly measuring 10–11 mm and severe dextroconvex thoracolumbar scoliosis. Umbilical cord length was normal, arguing against limb–body wall complex despite presence in this case of numerous typical diagnostic elements of this condition.

While 1.5T has been the standard, many centers are transitioning to 3T MRI for its improved SNR and spatial resolution, particularly for early-gestation anatomy. Recent research published in AJR provides further reassurance, showing no significant differences in neonatal growth parameters (e.g., birth weight, head circumference) between neonates exposed to 1.5T, 3T, or no MRI in utero.

Shailin Thomas, MD, discusses the AJR article by Danzer et al. supporting the safety of fetal MRI performed at 3T based on neonatal anthropometric measurements.

Bottom Line: Fetal MRI is most effective when part of a multidisciplinary team approach. Rads provide the diagnostic “missing link,” working with maternal-fetal medicine specialists, neonatologists, and pediatric surgeons to translate complex images into a clear plan for the family. By identifying whether an anomaly is isolated or part of a larger syndrome, MRI helps guide the timing and mode of delivery, ultimately reducing parental anxiety during a critical time.

In the ICU, thoracic POCUS is most impactful when applied systematically. Two frameworks anchor its use in acute respiratory failure: the BLUE protocol and lung aeration scoring. Together, they provide rapid diagnosis and quantitative monitoring.

BLUE Protocol Structures Diagnosis: The Bedside Lung Ultrasound in Emergency (BLUE) protocol, developed by Lichtenstein and Mezière, standardizes lung ultrasound evaluation in patients presenting with acute respiratory failure. Core elements include:

• Assessment of 2–3 predefined points per hemithorax
• Identification of key sonographic patterns:
  • A-lines (normal aeration)
  • B-lines (interstitial syndrome)
  • Absent lung sliding
  • Consolidation
• Adjunct venous ultrasound when pulmonary embolism is suspected

Rather than scanning the entire thorax, the protocol focuses on reproducible anatomical windows and interprets artifact patterns within a diagnostic algorithm. Validation studies report approximately 90.5% diagnostic accuracy in acute respiratory failure. BLUE’s strength lies in speed and structure, transforming artifact recognition into actionable bedside triage.

Chart summarizes bedside lung ultrasound emergency (BLUE) protocol as applied to patients with undifferentiated respiratory failure. This protocol includes two to three points: upper BLUE point (anterior below clavicle), lower BLUE point (anteriomedial between nipple and anterior axillary line), and posterior lateral alveolar/pleural syndrome (PLAPS) point (behind posterior axillary line at level of lower BLUE point). Diagnoses are indicated in white boxes. Designation of A profile means fewer than three B-lines are present in all imaged points and ultrasound is considered normal. B profile means more than three B-lines are present in multiple points and ultrasound is suggestive of pulmonary edema. C profile indicates consolidation, typically pneumonia. B’ profile indicates absent lung sliding with present B-lines, which suggests pneumonia. A’ profile indicates lack of lung sliding or B-lines suggesting pneumothorax. A/B profile indicates mix of A- and B-lines and suggests pneumonia.

Lung Aeration Assessment Quantifies Disease Burden: While the BLUE protocol classifies pathology, lung aeration scoring quantifies severity. This scoring system grades each lung region as follows:

• 0: A-lines or fewer than three B-lines (normal aeration)
• 1–2: Increasing B-line burden (partial loss of aeration)
• 3: Consolidation (complete loss of aeration)

Six regions per lung are evaluated, yielding a cumulative score from 0 to 36. Clinical applications include:

• Monitoring pulmonary edema and response to diuresis
• Assessing ventilator-associated pneumonia
• Guiding PEEP adjustments
• Predicting post-extubation respiratory distress

This approach enables longitudinal tracking. Instead of asking, “Is there edema?” clinicians can ask, “Is aeration improving?”

Complementary Roles: The two systems serve distinct but complementary purposes:

• BLUE protocol → Rapid etiologic diagnosis
• Aeration scoring → Severity assessment and treatment monitoring

Together, they represent a shift from qualitative bedside imaging to structured, reproducible, and semi-quantitative critical care ultrasound.

Clinical Takeaway: When applied correctly, thoracic POCUS is not an ad hoc scan; it is protocol-driven medicine. The BLUE protocol accelerates diagnosis in respiratory failure, whereas lung aeration scoring measures trajectory. In the ICU, this combination can change management within minutes.

Breast imaging during pregnancy demands heightened vigilance. Hormonal changes alter parenchymal appearance, masses can grow rapidly, and benign entities may closely mimic aggressive malignancies. Few examples illustrate this diagnostic tension better than the lactating adenoma, as Haydee Ojeda-Fournier, MD, explains during the ARRS Web Lecture “Breast Imaging: Special Patient Populations.”

Lactating adenomas are the second-most common mass encountered in pregnant and lactating patients. Imaging characteristics often mirror fibroadenomas and can be indistinguishable on both mammography and ultrasound. Therefore, definitive diagnosis typically depends on histology, rather than imaging alone.

These lesions are more frequently observed in the third trimester and often regress after delivery or once nursing begins—a reassuring natural history that supports conservative management when pathology confirms the diagnosis.

Solid Target: Physiologic lactational changes can introduce cystic elements, creating mixed solid–cystic morphology. When biopsy is indicated, precision matters: sampling the solid portion is essential to secure an accurate diagnosis and avoid false reassurance…as in the case of this 36-year-old postpartum patient (lump x 3 months) with biopsy-proved lactating adenoma.

Growth Raises Concern: Rapid enlargement should never be dismissed as purely hormonal. The differential remains broad, including phyllodes tumor, abscess, and malignancy.

In this case involving a 29-year-old patient with a quickly enlarging mass, biopsy confirmed a lactating adenoma—reinforcing that benign lesions can behave dramatically during pregnancy.

Diagnostic Trap! Consider the following scenario: two patients, both 39, both pregnant, both presenting with a mixed solid and cystic mass. One proves to be a lactating adenoma.

The other is triple-negative breast cancer. Imaging alone may not reliably separate the two.

This is the core interpretive hazard in special populations; pattern recognition must be paired with disciplined skepticism.

Pattern → Constraint → Advantage: Lactating adenomas frequently resemble fibroadenomas on imaging. → Mixed morphology and rapid growth can overlap with aggressive cancers, limiting imaging specificity. → Thoughtful targeting for biopsy and early tissue diagnosis convert uncertainty into clarity.

Clinical Takeaway: Pregnancy should lower the threshold for diagnostic rigor. Not raise it! When imaging features and clinical behavior diverge, tissue sampling is the safest path forward.

Bottom Line: In pregnant and lactating patients, the most dangerous mistake is assuming a reassuring pattern guarantees a benign process. Histologic confirmation remains the anchor of confident breast imaging in this population.

A new term is reshaping hepatology and radiology alike: at-risk MASH. As described by Claude B. Sirlin, MD, during the ARRS QuickByte “Latest Insights Into MASLD,” this subgroup represents patients with metabolic dysfunction–associated steatohepatitis (MASH) who have a nonalcoholic fatty liver disease (NAFLD) activity score ≥4 and fibrosis stage ≥2—the cohort most likely to experience liver-related outcomes and qualify for pharmacologic therapy.

Why “At-Risk” Changes the Conversation: MASLD progresses along a biologic continuum:

• Steatosis appears first and increases early.
• Inflammation and ballooning signal transition to MASH.
• Fibrosis stages 1–4 define structural progression.

Critically, as fibrosis advances, steatosis may decline—and in end-stage cirrhosis, fat may disappear entirely. This has major imaging implications. Proton density fat fraction (PDFF) is an excellent marker of steatosis and often correlates with MASH. But PDFF is not necessarily the best marker of at-risk MASH, because patients with significant fibrosis (stage ≥2) may demonstrate decreasing fat content.

In other words: less fat does not mean less risk.

A Therapeutic Threshold: The FDA approval of Resmetirom on March 14, 2024 marked the first pharmacologic therapy for MASH. However, this therapy is not broadly indicated. At approximately $50,000 per year, it is targeted specifically to patients with non-cirrhotic at-risk MASH (i.e., those with active disease and stage ≥2 fibrosis, but not cirrhosis). This shifts the rad’s role from descriptive to decisional. Identification now determines treatment eligibility.

The Quantitative Imaging Era: Eligibility criteria for Resmetirom were MRI-based, placing quantitative MR biomarkers at the center of clinical decision-making. This marks a broader transition: Radiology is moving from qualitative pattern recognition to measurable disease phenotyping. While MRI has led this evolution, ultrasound-based quantitative biomarkers are expected to follow, expanding access and scalability in the near term. Recently, Dr. Sirlin and Scott B. Reeder, MD, emphasized this shift in an editorial introducing rads to the expanding role of quantitative MRI biomarkers in metabolic liver disease.

Pattern → Risk → Responsibility: MASLD progresses from fat accumulation to inflammation and fibrosis. → Patients with MASH plus stage ≥2 fibrosis face liver-related outcomes and are candidates for therapy. → Rads must accurately stage fibrosis and quantify disease to guide referral and treatment.

Clinical Takeaway: The most important insight is conceptual . . . At-risk MASH is a fibrosis-driven definition, not a fat-driven one.

Quantitative imaging, particularly MR-based biomarkers, now determines:

• Who gets referred
• Who receives therapy
• Who remains under surveillance

This is not simply a nomenclature update. It is a reimbursement, therapeutic, and prognostic pivot point for abdominal imaging.

Bottom Line: In the era of approved therapy, identifying at-risk MASH is no longer optional precision; it is actionable medicine.

When a pediatric patient presents with back pain, MRI of the spine is a powerful tool to distinguish between benign and malignant processes. In this case of a 7-year-old girl from a Quick Byte presentation by Laura M. Fayad, MD, the imaging reveals systemic replacement of the normal bone marrow.

Primary Observations

• Darkness: On T1-weighted imaging, the marrow signal is abnormally dark.
• Vertebral Compression: Multiple areas of the spine show vertebral body height loss and fractures.
• Diagnostic Worry: Indeed, this combination of diffuse signal abnormality and pathologic fractures is highly concerning for leukemia.

Dixon for Clarification: To confirm if the marrow has been replaced by tumor, a variation of the in-and-out-of-phase gradient echo, the Dixon technique, can be used. Dixon provides fat-only and water-only images to isolate specific tissues.

• Fat-Only Imaging: In a normal patient, fat should be visible within the marrow.
• The Dropout Test: In this patient, while fat is clearly visible in the subcutaneous and epidural spaces, there is a complete absence of fat signal within the bone marrow.
• Conclusion: The total lack of marrow fat indicates that the space has been entirely replaced by malignant cells.

Fat Fraction Analysis: Beyond visual inspection, we can measure the MRI fat fraction to provide an objective data point.

• 10% Rule: In pediatric patients, a fat fraction of less than 10% is a significant indicator of malignant bone marrow.
• Comparison: Normal control marrow typically maintains a much higher fat fraction, often ranging from 20% to over 50%.

Marrow Category	MRI Fat Fraction (%)	Clinical Significance
Malignant	< 10%	Highly concerning for leukemia or tumor infiltration.
Normal (Controls)	> 20%	Indicates healthy, fat-containing marrow for age.

The Problem: Traditional CTA is a structural map. It tells you there is a fallen tree on the road (i.e., the clot), but it doesn’t always tell you if the traffic has stopped (i.e., the perfusion). In subsegmental disease or “dirty” scans with beam-hardening artifacts, structural-only imaging leaves radiologists in the equivocal trap.

The Fix? As the ARRS Online Course “Practical Dual-Energy CT Throughout the Body” points out, by pairing iodine quantification with anatomical imaging, rads can move from searching for filling defects to visualizing physiologic impact.

The Breakdown—A multi-vector look at a left subsegmental PE...

Standard Blended—We see the “What.” A classic peripheral wedge-shaped opacity: Hampton Hump (solid arrow). There is a subtle luminal filling defect in the feeding vessel (arrowhead), but in a motion-degraded scan, you might doubt it.

Iodine Map—We see the “So What.” The red overlay represents iodine concentration. The dashed arrows highlight a perfusion “cold zone.” This wedge-shaped defect provides orthogonal confirmation that the clot isn’t just an artifact; it’s a functional obstruction.

Vessel Analysis—This reconstruction isolates iodine signal. Note the iodine dropout (arrowhead) within the artery. This removes the noise of the lung parenchyma to focus strictly on the continuity of the blood column.

3D Perfusion—The “Global Impact.” This 3D volume rendering maps the total territory of the ischemic lung (red zones). It’s the visual shorthand for clinical severity.

Push for DECT in Your PE Protocol?

• Tie-Breaker: Small distal clots are often equivocal. If you see a corresponding wedge-shaped perfusion defect on the iodine map, your confidence in calling a subsegmental PE jumps from “possible” to “definitive.”
• Artifact Insurance: Beam hardening from dense contrast in the SVC often obscures the right upper lobe. DECT iodine maps help differentiate true clots from “pseudo-filling defects” caused by photon starvation.
• Infarct Prediction: A Hampton Hump is a late sign of infarction. DECT identifies the ischemic penumbra (the area at risk) before it potentially progresses to permanent tissue death.

Bottom Line: DECT transforms PE imaging from a binary search (clot vs. no Clot) into a physiologic assessment (obstruction + ischemia). Result? Fewer “equivocal” reports and higher diagnostic defensibility.

Dual-energy CT (DECT) is becoming a must-use tool in musculoskeletal (MSK) imaging—not just for hardware, but for crystals, marrow, and trauma. Orthopedic imaging often suffers from two problems: metal streak and ambiguous density. But as the ARRS Online Course “Practical Dual-Energy CT Throughout the Body” duly notes, DECT tackles both by separating materials and controlling photon energy, giving rads clearer views of bone, soft tissue, and implant interfaces.

Where Does DECT Make the Biggest Difference?

1. Metal Artifact Reduction (MAR) That Actually Works

High-keV VMIs (110–150 keV) reduce photon starvation and scatter from:

• Spine instrumentation
• Hip and knee arthroplasties
• Fracture fixation hardware
• Shoulder anchors

Result: cleaner cortices, more visible fractures, and better evaluation of infection or loosening.

Portal venous phase abdominal CT images obtained after spinal reconstruction surgery. Left, Normal blended image shows considerable amount of metal artifact (arrow) overlaying left kidney and good contrast in portal veins (arrowhead). Center, Virtual monoenergetic image of same slice shown in Left, obtained at 50 keV, shows high portal venous contrast (arrowhead) and high amounts of metal artifact (arrow).Right, Virtual monoenergetic image of same slice shown in Left, obtained at 150 keV, reveals decreasing amounts of metal artifact (arrow) and loss of portal venous contrast (arrowhead).

2. Crystal Imaging: Knowing Exactly What You’re Looking At

Material decomposition differentiates uric acid from calcium, which helps:

• Confirm gout even in unusual locations (spine, tendons, postoperative joints)
• Distinguish gout from infection or tumor
• Map tophus burden for treatment decisions

Patient with suspected tophus of first interphalangeal joint caused by gout. Left, Mixed CT image that is equivalent to single-energy scan acquired at 120 kVp shows tophus (arrowhead). Right, Material decomposition image applied to highlight urate crystals (green area indicated by arrowhead) confirms that lesion seen on regular CT scan is tophus caused by gout.

3. Bone Marrow Edema Detection

DECT water-specific reconstructions reveal bone marrow edema in trauma, stress injuries, and arthritis (especially helpful when MRI is unavailable or contraindicated).

Why Are MSK Rads Adopting DECT?

• Saves nondiagnostic postoperative studies
• Improves fracture conspicuity
• Reduces MRI dependence
• Helps differentiate infection, inflammation, and crystal deposition
• Speeds up decision-making for orthopedic surgeons

Bottom Line: MSK DECT is no longer just “nice to have.” When hardware, crystals, or marrow ambiguity stand in the way, DECT gives you answers a conventional CT simply can’t.

PSA screening alone lacks specificity, leading to substantial overbiopsy and detection of indolent disease. Nomograms—multivariable risk calculators—were developed to move prostate cancer assessment beyond single thresholds. As Drs. Benjamin Tran, Janelle T. West, Soroush Rais-Bahrami, and Kristin K. Porter noted in their ARRS Online Course, the most effective tools integrate clinical variables with mpMRI, making rads central to risk stratification rather than downstream reporters.

Why Nomograms Matter: Traditional PSA-based decision-making treats all patients similarly despite wide variation in underlying risk. Nomograms combine multiple predictors—PSA, prostate volume, digital rectal exam, age, biopsy history, and increasingly PI-RADS assessment—to estimate an individual’s probability of harboring clinically significant prostate cancer (csPCa).

Multiple studies show that nomograms incorporating MRI outperform PSA alone and MRI alone, improving discrimination while safely reducing unnecessary biopsies.

mpMRI’s Role: mpMRI is not just an add-on variable; it is a dominant driver of modern risk models. PI-RADS category, lesion size, and PSA density materially alter predicted risk.

MRI-integrated nomograms consistently achieve AUCs in the 0.80–0.88 range for csPCa detection, while reducing biopsy rates by 20–34% depending on the population and risk threshold chosen. In practical terms, this means fewer low-yield biopsies without a clinically meaningful increase in missed aggressive cancers.

For rads, this elevates the importance of:

• Accurate PI-RADS categorization
• Consistent prostate volume measurement
• Clear reporting of lesion location and size

Small changes in PI-RADS score can significantly shift nomogram output and clinical decision-making.

47-year-old man with history of two negative systematic biopsies at another facility and increasing PSA level (most recently, 35.6 ng/mL). Multiparametric MRI was performed for persistent clinical suspicion of clinically significant prostate cancer

Top to Bottom: Axial T2-weighted (Top), axial high-b-value (2000 s/mm2) (Middle), and calculated ADC (Bottom) MR images show left apical anterior central gland lesion (arrow) with very high suspicion of being clinically significant prostate cancer. Lesion is PI-RADS category 5. MRI–transrectal ultrasound fusion biopsy of lesion resulted in pathologic diagnosis of prostatic adenocarcinoma, Gleason 4 + 3 = 7 (grade group 3). Gleason 4 pattern represents 60% of tumor. Prostate volume calculated with MRI is 40 mL.

PSA Density—A Critical Modifier: PSA density (PSAD) is one of the most powerful adjuncts to PI-RADS. In patients with PI-RADS 1–2 or equivocal PI-RADS 3 lesions, PSAD meaningfully improves negative predictive value—often approaching 90%—and helps identify patients who can safely avoid biopsy.

This is especially relevant in biopsy-naïve men, where avoiding the first biopsy carries the greatest downstream benefit.

Matching Nomogram and Patient: No single nomogram fits every clinical scenario. Some are optimized for biopsy-naïve patients, others for men with prior negative biopsy, and some for mixed cohorts. Understanding these distinctions prevents misapplication and overconfidence in a single risk estimate.

Another important limitation is population dependency. Many widely used nomograms were derived from European or predominantly White cohorts. Without external validation, these tools may overestimate risk in Asian populations and other underrepresented groups. Local calibration and clinical judgment remain essential.

47YO man with two negative systematic biopsies (same patient)

Screenshot of Stanford Prostate Cancer Calculator (SPCC) nomogram calculation shows 99% probability of clinically significant prostate cancer before repeat biopsy. This prediction can be shared with patient during counseling about recommendation for repeat biopsy. Result of repeat MRI– transrectal ultrasound fusion biopsy was consistent with prostatic adenocarcinoma: Gleason 4 + 3 = 7 (grade group 3). Gleason 4 pattern represented 60% of tumor.

What Does This Mean for Rads? Nomograms reposition rads as active participants in prostate cancer decision-making. High-quality MRI interpretation directly influences whether a patient undergoes biopsy, surveillance, or reassurance.

In multidisciplinary care, radiologists who understand nomogram inputs and limitations can:

• Explain risk estimates to urologists with confidence
• Support biopsy deferral when appropriate
• Improve alignment between imaging findings and management

Nomogram / Calculator	Best Use Case	Key Inputs	Strengths	Limitations
MRI-ERSPC RC3 / RC4	Biopsy-naïve patients	PSA, PSAD, DRE, prostate volume, PI-RADS	Strong external validation; good balance of biopsy reduction and csPCa detection	Derived largely from European cohorts
ModRad	Biopsy-naïve patients	PSA, PSAD, PI-RADS, clinical variables	High discrimination; MRI-forward design	Less validated in prior biopsy populations
ModDis	Prior negative biopsy	PSA, PSAD, PI-RADS, biopsy history	Reduces repeat biopsies while maintaining csPCa sensitivity	Less applicable to biopsy-naïve patients
Stanford Prostate Cancer Calculator	Mixed populations	PSA, DRE, biopsy history, MRI findings	Broad applicability; flexible inputs	Slightly lower performance than MRI-specific models
PCPT Risk Calculator	Legacy / screening context	PSA, age, race, DRE	Historically influential	Does not incorporate MRI; lower specificity
ERSPC (non-MRI)	Screening populations	PSA, DRE, prostate volume	Well studied	Outperformed by MRI-integrated tools

Bottom Line: mpMRI-integrated nomograms transform prostate cancer assessment from threshold-based screening to personalized risk prediction. Radiologists who deliver precise PI-RADS scoring and understand how those scores drive nomograms add measurable, patient-level value.

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The American College of Radiology (ACR) is sounding the alarm for hospital-based imaging providers: a recent, massive pay increase for Coronary CT Angiography (CCTA) is at risk of being revoked unless facilities change how they bill for these services.

Big Picture: In its 2025 final rule, CMS temporarily moved CCTA (CPT 75572–75574) from a Level 1 to a Level 2 Ambulatory Payment Classification (APC).

The Windfall: Technical fees jumped 104%, rising from $175 in 2024 to $357 currently.

The Catch: CMS made this change “provisionally.” If fewer than 50% of hospitals update their billing to reflect the true resource intensity of CCTA, Medicare will revert to the lower, generic CT payment rates.

	CY 2024APC 5571	CY 2025APC 5572	% Change
Hospital Outpatient (OPPS)	$175	$357	+104%
Physician Office (PFS)	$285	$318	+12%

The Friction: Historically, hospitals were forced to use a generic “CT Scan” revenue code (0350), which has a lower cost-to-charge ratio. CMS has now removed the “Return to Provider” edits that blocked hospitals from using more accurate codes.

Action Items: To make the pay hike permanent, the ACR, American College of Cardiology, and Society of Cardiovascular Computed Tomography all recommend:

• Update Charge Masters: Map CCTA CPT codes to Cardiology (0480/048x) or Other Imaging Services (040x) revenue codes.
• Reflect Intensity: Reporting costs under these specific codes demonstrates the specialized nursing and resource needs that justify the higher APC level.
• Monitor Denials: Ensure clearinghouses and private payers accept the updated cardiology revenue codes.

Bottom Line: If facilities continue to report CCTA expenses as identical to generic CT scans, the data will fail to support the higher payment level, and the $182-per-scan “bonus” will vanish.

Dual-energy CT (DECT) has become a workhorse in emergency imaging, particularly for iodine mapping and virtual noncontrast applications. But as Aaron Sodickson, MD, reveals in a presentation now available in the ARRS Quick Bytes library, conventional DECT systems come with a quiet limitation: dual-energy information is not uniformly available across the entire field of view. Photon-counting CT (PCCT) changes that.

There Are Limits: On many high-end dual-energy scanners, iodine maps are only reliable within a central circular region. Outside that area, dual-energy information is lost. In large patients or peripheral anatomy, this can mean incomplete iodine characterization and diagnostic uncertainty.

In practice, you may see clean iodine signal centrally, but nothing at the edges—simply because the system cannot acquire dual-energy data beyond that geometric constraint.

PCCT Is Built Different: PCCT acquires spectral information directly at the detector. Because it does not rely on paired detector geometries or source-based separation, dual-energy information is available across the entire field of view, meaning:

• Iodine maps extend fully to the periphery
• Large patients no longer fall outside the dual-energy zone
• Edge anatomy benefits from the same spectral data as the center

In the ED, where patient size and positioning are unpredictable, this matters.

Better-Behaving Noise: Another practical advantage of PCCT is cleaner iodine post-processing. DECT maps may show speckled signal in non-enhancing structures—algorithmic noise that can mimic low-level enhancement.

In this example below of a renal cyst, conventional DECT shows scattered orange signal that is not true enhancement. On PCCT, that noise is substantially reduced, allowing confident classification of a benign, non-enhancing complex cyst.

Why This Matters in the ED: Emergency radiology rewards speed and certainty; PCCT improves both by:

• Preserving iodine data across entire image
• Reducing false-positive enhancement
• Increasing confidence in lesion characterization
• Decreasing need for follow-up imaging

Bottom Line: Photon-counting CT removes the “edge problem” of conventional DECT. By delivering full-field spectral data with improved noise characteristics, PCCT strengthens iodine-based interpretation—exactly where ED imaging needs it most.