Renal Mass: Diagnosis and Management

• The lesson covers nephrology and urology diagnostic imaging.
• 10/10/2024 – Group #17(Giulia Dani and Anna Ghenciu)

Clinical Case

• 65-year-old male patient
• Symptoms include abdominal pain, urinary retention, fever, and leukocytosis
• Ultrasound and X-ray are options for the 1st level method of imaging.
• An X-ray was performed instead of an ultrasound

Abdominal X-ray Findings

• Central-posterior view shows the lumbar spine, ribs, and soft tissue.
• Soft tissue rendering is poor
• A hyperdense structure is visible in the left flank, leading to the ultrasound finding of stones (lithiasis).
• Hydronephrosis is present.
• X-rays are used over ultrasound when bowel air is present to rule out bowel obstruction.
• Lighter spots indicate lithiasis
• Lithiasis = Stones

Ultrasound Imaging

• Gives a better depiction of the morphology of the kidneys and urinary tract
• The first image represents the right kidney, and the second represents the left kidney
• Stones appear as hyperechoic structures in the left kidney
• Uses sound waves of 2 to 17 MHz
• Images result from the propagation and reflection of sound waves
• The time taken for sound waves to return gives tissue position information
• Does not use ionizing radiation
• Operator dependent
• Cannot penetrate bone

Uro-CT

• A 2nd imaging modality is needed to assess stone location and kidney damage
• A particular application of computed tomography
• Is essential for evaluating obstruction and renal function
• Two phases: CT without contrast and urographic phase

Imaging Modality Steps

• Initial diagnosis
• Detection (site, volume, morphology)
• Characterization
• Disease balance
• Staging
• Therapeutical planning
• Follow up
• Response to therapy

Urinary System

• Located in the retroperitoneal area, comprising kidneys, ureters, bladder, and urethra.
• Studied by X-ray (excluding ureters), conventional urography, CT urography, and MR urography

Ultrasound Exam

• The 1st exam of choice for detecting primary lesions of the kidney (cystic/solid).
• Useful for calculi (upper – kidney - & lower – bladder urinary tract)
• Useful for trauma
• Important signs include dilation duct and hyperechoic structures
• Visualization of the ureters may not be optimal.
• Useful under the interventional point of view
• Useful for renal cyst drainage
• Useful for extracorporeal shock wave lithotripsy

Normal Kidney Ultrasound

• Normal adult renal length is 9 to 12 cm, depending on patient characteristics.
• The kidneys should be smooth in outline
• Parenchyma surrounds the central echodense region (renal sinus), including the pelvicalyceal system, fat, and blood vessels.
• Normal ureters are not usually visualized due to overlying bowel gas.
• Patients should drink water 30 minutes before ultrasound for a good echoic window for the bladder.
• Ureters can be seen in the intramural part of the bladder.
• The urinary bladder should be examined in the distended state; the walls should be sharply defined and barely perceptible.
• Can assess post-micturition residual volume of urine using measuring micturition.

X-Rays

• Basic densities: air (black), soft tissue, fat, bone (white)
• Grays in between can be seen
• X-rays with contrast can find kidneys by locating the lumbar spine between L1-L3.
• The technician can change the TW to highlight the kidneys, liver, and spleen.

Conventional Tomograms

• Tomograms, known as plain film tomograms, are radiographs that evaluate a specific plane within the body
• Evaluated by blurring out tissues above and below the plane of interest.
• Approach images by looking for calcifications, abnormal soft tissue, air within the urinary tract, and bony abnormalities.

Urography

• A combination of morphological and functional assessment of the urinary tract through a contrast agent.
• Iodine contrast is administered intravenously and eliminated via the urinary tract.
• Dynamic phases are captured at various timings.

Three Dynamic Phases of Urography

• Nephrogram Phase
• Ureterogram
• Cystogram

Urography Phases

• In the cortex phase, there is contrast in the cortex.
• In the pelvis phase, there is contrast in the pelvis.
• In the ureters phase, there is contrast in the ureters and bladder.
• If a lesion or pathology is present, a positive or negative image can be seen.
• Contrast can also be given percutaneously or trans-nephrostomic (for nephrostomy conditions).
• It can also be directly put inside the bladder (cystogram) to assess the presence of obstruction in the bladder or urethra.

Typical Timings of Urography

• Immediate film: before contrast
• After 5-15 minutes (from contrast administration) film: Nephrogram phase
• 30 minutes film: Ureterogram phase
• 45 minutes film: Cystogram phase
• Postvoiding film (=after urination)

Pyelography

• Pyelography involves direct percutaneous or trans-nephrostomic opacification of the urinary tract.
• Can be anterograde or retrograde
• Retrograde involves selective catheterization of the ureters during cystoscopy.

Retrograde Cystoscopy

• Transuretral administration of iodine contrast agent
• Assesses uretral anatomy and function

CT Urography

• It studies the urinary system using CT imaging
• Used for a comprehensive evaluation of the excretory system
• Uses axial CT with thin collimation for the excretory phase, high-resolution datasets, and multiplanar reconstruction.

CT Urography Protocols

• Single bolus - triple phase
• Steps for Triple Phase
• Pre-contrast visualizes lithiasis, calcifications, HU of solid lesion, and hemorrhage.
• Nephrografic face of superior abdomen using single bolus (100-150 ml, 2-4 ml/sec) assesses renal parenchyma, masses, and flogosis
• Arterial phase is the first phase just after contrast administration, when contrast medium passes through the arteries: cortex is very bright
• Parenchymal phase is the second phase with the contrast medium passing through the cortex
• Wait from 9 to 12 minutes for the contrast to reach the bladder (12-20 if obstruction is present) for the excretory phase
• Slice thickness of < 3 mm, slice overlap 50% voxel isotropic for 3D reformatting
• Can reconstruct a 3D model

Clinical Indications for CT Urography

• Contrast picture on the axial plane, represents the left kidney.
• It's possible to see a kidney stone which causes hydronephrosis
• Kidney stones located in the 3rd part of the ureter (bigger than normal) can only be seen by CT Urography (and maybe X-ray).
• CT urography: represents an excretory phase
• Since all the contrast is in the pelvis
• Minus image, represents a non-calcified calculus.
• Study the bladder and the presence of masses within it.
• Visualize malformations, vascular abnormalities, solid and neoplastic masses

Magnetic Resonance Imaging (MRI)

• Imaging technique, uses non-ionizing radiation to create tomographic diagnostic images that can be oriented on any spatial plane
• Relies on magnetic fields and radiofrequency waves.
• Better defines soft tissue characterization without using ionizing radiation.
• Special techniques
• Pyelography (MRI U t2)
• Urography with Contrast Enhancement (MRI U t1).
• Pyelography involves T2-weighted images with great magnification of static fluids (water).
• Urine serves as a contrast agent
• Used to investigate excretory system morphology, collecting system dilations, obstruction site and pregnancy and pediatric populations.
• Urography uses T1-weighted images
• Better visualizes anatomical 3D images with Contrast agent (3D GRE□Gadolinium ev).
• MRU can determine the function (glomerular filtration rate (GFR))

Methods

• Ultrasound the 1st choice
• CT Urography the 2nd choice
• MRU in particular Pyelography the 3rd choice

Urinary Tract Malformations and Diseases (UTMD)

• Renal dysmorphisms and parenchymal malformations are commonly seen during CT and Ultrasound evaluations
• Incidence of 1/500 adults, mainly displayed by male.

Horseshoe Kidneys

• The kidneys fuse together at the bottom
• Assume a horseshoe shape (U shape).
• Usually discovered because in ultrasound the end of each kidney cannot be found
• Confirmation given by further CT examination.
• Symptomatic and an incidental finding
• Several complications and clinical conditions
• Hydronephrosis
• Renal calculi
• Increased susceptibility to traumas, infections, malignancy (transition cell carcinoma of the renal pelvis)
• Increased incidence of renal vascular hypertension

Renal Ectopia

• An abnormal localization of the kidney.
• Lumbar kidney, a pelvic kidney, etc.

Renal Agenesis

• Congenital one (1/500 births) or both (classic Potter syndrome) absence of kidneys
• Visualized during Ultrasound evaluations.
• If bilateral it is usually fatal. Instead, unilateral agenesis still allows the patient to have a normal life expectancy.
• Unless identified on antenatal screening, it is incidentally found when the abdomen is imaged for other reasons.
• Patients with unilateral renal agenesis develop secondary hypertension

Primary Megaureter

• A basket term encompassing causes of enlarged ureter
• Obstructed primary megaureter
• Refluxing primary megaureter
• Vesico-ureteric reflux [VUR] is not considered separately
• Non-refluxing unobstructed primary megaureter

Hydronephrosis

• An obstruction in The urinary tract.
• Causes an increase in pressure
• Enlargement of kidneys, presses against nearby organs.
• It is detected with Ultrasound or CT imaging.

First-grade Hydronephrosis

• Is associated with pelvis dilation
• Second-grade - pelvicalyceal system dilatation (dilation of major calyces)
• 3rd grade - cortical thinning
• Also minor calyces are dilated, but still parenchyma is spared.
• Fourth-grade is considered an emergency
• Parenchyma is compromised
• The cortex cannot be seen anymore
• Nephrostomy must be performed. With grade 1 and 2 usually the patient is under control, and we wait before intervening.

Nephrostomy

• First described in 1953
• Intervention performed if a urinary obstruction secondary to calculi
• Urinary fistula
• Decompression of perinephric fluid collections
• Ultrasound or fluoroscopy formed

Nephropathies

• Mainly investigated by CT
• Ultrasound role limited, insensitive to change in acute phase
• Look for reduced enhancement, typical focal wedge-like lesion in the cortex, swollen cortex, and reduce enhancement compared

Pyelonephritis

• Heterogenous group of upper urinary tract infections
• Inflammation of renal calyces, renal pelvis, and renal parenchyma.
• CT is mainly used to detect
• Ultrasound insensitive to changes in acute pyelonephritis
• reduced enhancement, swollen focal wedge-like regions.
• Features: particulate matter/debris in the collecting system, reduced areas of cortical vascularity by using power Doppler, gas bubbles and abnormal echogenicity of renal parenchyma.

Renal Focal Lesions

• Renal masses are incidentalomas (found out by accident on US, CT, MR)
• Almost all simple cysts, but in 5% the lesion are solid masses
• Tumors Size, shape, margins, structure, location is investigated.

Renal Masses Types

Divided into non surgical and non surgical which are :

• Renal masses
  • Angiomyolipoma
  • Oncocytoma
    • Pseudotumor
    • Lymphoma
• Surgical
  • Renal carcinoma
  • Transitional carcinoma
• Complex cystic lesions

Non Surgical Masses Summary

• Angiomyolipoma is most common benign solid renal lesion
• Well-defined and heterogeneous
• Located in the renal cortex
• Containing fat (density on CT < 0, usually -20)
• Assocated with other pathologies such as tuberous sclerosis, VHL and NF1,
• Most often sporadic
• Prevalance for women (4:1)
• Asymptomatic findings. There may be calcification and necrosis

Oncocytoma

• Is the second most common finding of renal masses
• Represents the 5% of adult renal neoplasm
• Peak in early to mid 50’s
• Lesions Sharp Demarcation
• In MR hypointense on T1W and hyperintense on T2W (hypointense scar)
• Typically solitary in the renal cortex, but can be mutifocial of bilateral
• 2-12cm in diameter

Surgical Mass

• Most Common one is Renal Cell Carcinoma {RCC}
• RCC (Renal Cell Carcinoma)
• Incident findings are typically in cortical region towards the surrounding area.
• Non-Urinary or asymmetrical symptoms
• Can be associated with hereditary
• The most common subtype is RCC {clear cell Carcinoma}
• Papillary then chromophobe RCC
• Finally Medullary Carcinoma

Clear-Cell Carcinoma

• 70/80% of cases are
• Can be found in the cortex
• Spread of metastasis to lung, bone, and liver
• 3d view through a CT Machine
• Role of CT
• It shows metastases or presence within the structure.
• Tends to be typically heterogeneous, used to help separate
  • TlW , t2w images and can reveal Hypointense
  • Pesdocapsule can be differentiated

Papillary Carcinoma

• Accounts 10-15% off all RCC’s
• 2nd most common
• Typically Bilater homogeneous and hypovascular and can mimic cyst
• Rare occurrence in hereditary setting.
• 80-90% are survival are asymptomatic cases

Imaging

• Ultrasound- can be mimic a cyst with heterogeneous appearance
• Solid Homo mass, less enhancement
• CT with little cortex shows less enhancement from clear-cell Carcinoma
• progressive enhancement in Excretory phase
• in MR are isontpense

Cysts and Complex masses

• Often cyst don’t require treatment but will include follow up and surgery.
• Bosniak Classification- it differentiates the approach we use to use
• Renal Mass = surgical( eg categories 3-4) Nonsurgical-(eg Benign 1-2)

After Bosniak Original Description.

• Cysts in category 2 are slightly more complicated. But not enough to be placed into category III
• 2F for follow up in 1993
• Simple Cysts- small walls or not seen and will appear hyperechoic but are totally benign/rounded they are ignored
• Categorized 2 - very tin calcifications inside but are very complicated. Still Benign w/ some inner septa walls.
• Minimal complex, number of followups is needed due to a minimal thickness within the structure
• A light enhancement will be included to enhance the post contrast
• Indeterminate masses usually get surgery due to differentiation and high variety
• There will be thick septa, the nodularity is on the spectral and are hyperdense on CT calcifications. Usually treated with Neptune or radiofrequency ablation for radiation
• 4- will come up as malignant where a part contains both cystic parts and mass protion and can contain polythene
• The Kidneys are difficult to access or lesions within them.

Home message: ( Complex Cystic Masses)

• It’s crucial to differentiate/distinguish surgical from non surgical mass
• Determine what constitutes a lesion from the cyst
• Use Bosniek classification
• Exclude tumor limits- like abscess, etcetera
• Exclude lymphomas, 2 level is used You must consider the specifically characteristics from images and find
• pseudo masses:
• tumor mimics, the pt case history and clinical findings will help determine diagnosis A:Abscess is similar to a complication of acute pyenlophris. patients can present both flank pain and fever, also in urinary region.

Home Message (differentiation of renal masses )

• First determine wether the lesion is a cyst 2-if cyst, then its a benign angiomyo, look for macroscopic fat 3-exlude tumourmimivs , that is to separate in clin sets 4 - exclude metastsis vs lymoh. and use CT and Mr

For The end

Explore diagnostic imaging modalities like CT scans to identify renal masses and differentiate them. Different types of renal lesions, management approaches, and the Bosniak classification are discussed. Learn about benign and malignant masses.