Prostate Imaging PDF

Nephrology and Urology Catapano - Radiology - Lesson 02: Prostate Imaging 17/10/2024 - Group #26 (Alice Marazzo and Chiara Learmonth) Urogenital Imaging Bladder: X-Ray Plain radiography is not a feasible method for...

Nephrology and Urology Catapano - Radiology - Lesson 02: Prostate Imaging 17/10/2024 - Group #26 (Alice Marazzo and Chiara Learmonth) Urogenital Imaging Bladder: X-Ray Plain radiography is not a feasible method for imaging the urinary bladder, as it provides limited information. However, it may occasionally detect incidental findings, such as stones (lithiasis) or the presence of air, which can occur in conditions like emphysematous cystitis. A voiding cystourethrogram (an X-ray procedure where contrast is injected into the bladder and images are taken while the patient urinates) is more useful for identifying abnormalities in the urethra and bladder. This procedure is particularly valuable in paediatric cases, as it helps detect conditions like vesicoureteral reflux (where urine flows backward from the bladder into the kidneys). A cystogram, another imaging study where contrast dye is injected into the bladder and X-rays are taken to assess the bladder’s structure, still has an important role in the evaluation of traumatic bladder rupture, helping to visualise any structural damage. Ultrasound (US) The US is the preferred bladder imaging tool as it is convenient, safe and relatively inexpensive. It is also able to diagnose a wide variety of pathologies that can be found within the bladder. For an initial investigation in a patient with a voiding disorder, an US cystodynamogram is considered the investigation of choice. This non-invasive procedure allows for the evaluation of bladder function and structure during the filling and voiding phases, providing crucial information for diagnosis. In the assessment of children with urinary tract infections (UTIs), a combination of bladder ultrasound, plain abdominal X-ray, and renal ultrasound has become the standard initial investigation. This approach helps identify any structural abnormalities in the urinary tract that may contribute to infection or dysfunction. Computed Tomography (CT) CT is considered a second-line imaging tool for bladder evaluation, often used when ultrasound (US) is insufficient. Conditions commonly referred for CT include urolithiasis (urinary stones) and hematuria (blood in the urine). One of the key advantages of CT in bladder imaging is its ability to assess the precise location of stones, such as in the uretero-vesical junction. In addition, CT can evaluate the stone burden (the size and number), composition, and fragility (likelihood of breaking), which are essential factors in determining appropriate treatment 1 strategies. CT’s accuracy in assessing stone characteristics makes it particularly useful when stones in the distal ureters and bladder are not detectable on ultrasound. CT is also valuable in the staging of bladder cancer. While it cannot detect small, superficial bladder tumours, CT urography (CTU) is reliable for detecting more advanced bladder cancers and is the gold standard for staging lymph node (N) involvement and distant metastases (M). In cases of gross hematuria, CT can differentiate intraluminal blood clots from urothelial tumours, providing essential information for diagnosis and treatment planning. Magnetic Resonance (MRI) MRI is also a second-line modality tool after US. The use of MRI in bladder imaging is generally limited due to its higher cost and the effectiveness of ultrasound (US) in diagnosing most major bladder diseases. However, gadolinium-enhanced MRI is a valuable tool with high accuracy, particularly when it comes to determining the T stage (tumour invasion depth) of bladder cancer, making it the gold standard for this purpose. In summary, we initially use ultrasound (US) for screening bladder conditions. While the interpretation of images from CT and MRI shares similarities, each modality serves distinct purposes. CT is essential for staging bladder cancer, helping to assess how far the disease has spread, whereas MRI is valuable for evaluating the presence of cancer and examining the bladder's volume to identify any potential problems.T Looking at the US Image above: 2 It is a sagittal view of the bladder, we know it is full due to the presence of urine seen as anechoic areas (dark areas). A mass (arrow) can also be observed in the bladder. Distinguishing between a large blood clot and a tumour using only ultrasound can be challenging. To gain more information, we typically ask the patient to change positions. By doing this, we can observe if the mass moves within the bladder, which can help us determine its nature. This allows us to assess the mass more accurately, noting any changes in its position from one side of the bladder to the other. An MRI is then asked for, as it is particularly helpful in these cases, providing detailed information about the bladder and any masses present. If a diagnosis of bladder cancer is confirmed through MRI, we typically follow up with a computed tomography (CT) scan for staging. This helps determine the extent of the cancer and its spread, which is crucial for planning treatment. Virtual Reality Imaging The application of virtual imaging in medicine is increasingly important and widespread, particularly in the field of radiology, and is likely to become a standard practice in the future. We utilise 3D reconstructions from computed tomography (CT) images, which are obtained using very thin slices. This technique allows us to create detailed volume renderings that physicians can use to simulate virtual endoscopy. It is widely applied in this context. As previously discussed, these 3D reconstructions can be performed with CT to evaluate the entire urinary tract. The above image shows how we are able to navigate within the urethra. 3 We can also navigate within the bladder. One example is a small pedunculated lesion located on the left side of the bladder wall. In the CT image, this lesion appears as a hypodense area, and through 3D reconstruction, we can assess the structures surrounding this tiny, approximately three-millimetre, lesion in the posterior wall of the bladder dome. This method is important because it allows for a rapid and accurate assessment of bladder lesions, including diverticula and small tumours. However, it is essential to note that while Virtual Cystography can provide valuable diagnostic information, it cannot assist with biopsy or provide in situ diagnosis; and therefore Fluorescence and conventional cystoscopy remains the gold standard for diagnosing bladder lesions and cancer. Clinical Point of View One of the most common forms of bladder cancer is the transitional epithelial cell carcinomas. Transitional epithelial cell carcinomas are most commonly observed in males, occurring more 4 than four times as frequently as in females. This type of cancer typically affects men over the age of 60. Risk factors include a history of smoking and certain occupational exposures, such as those related to pigment manufacturing. Squamous cell carcinoma of the bladder accounts for a small percentage of bladder tumours. It is most commonly observed in Egypt, primarily due to schistosomiasis infections. This type of cancer typically arises after chronic irritation of the bladder, often caused by schistosomiasis. Additionally, chronic bladder stones can also lead to prolonged irritation of the bladder walls, which may contribute to the development of dysplasia and, eventually, carcinoma. Clinically, the presentation of bladder cancer can be similar across different types. Hematuria is the most common symptom, but patients may also experience other urinary symptoms such as dysuria. In cases where the tumour is large, a palpable mass may be felt in the abdomen. Because of the similarities we first need to assess the T parameter. The T parameter is the first aspect to assess in bladder cancer staging, and MRI is the primary imaging modality used for this evaluation. The key differentiation involves identifying stages where the tumour is non-muscle invasive (Ta-T1 Stage) versus those where there is muscle invasion (T2, T3, T4). This distinction is crucial as it significantly influences treatment decisions for the tumour. Following ultrasound, MRI allows us to identify the lesion, evaluate its morphology (shape and structure), determine the extent of the tumour, and assess for lymph node involvement, (particularly in the hilum and regional areas). 5 In this image we can see the bladder on the left is T2 weighted. In T2-weighted MRI, fluids such as urine produce a hyperintense signal (bright areas), making it easier to differentiate between the bladder wall and the fluid. In the MRI on the left, the bladder is clearly filled with fluid, and the bladder wall appears hyperintense in certain areas, enhancing the visibility of the bladder layers. Being able to see the different layers, we are able to see a strong correlation between pathology and the diagnostic images, making it highly useful for identifying abnormalities. The MRI on the right is T1 weighted and the wall seems homogenous. Additionally, T2-weighted imaging can be particularly valuable when no contrast agent is used, as it still allows for detailed visualisation of the bladder and urinary tract. The combination of T1 and T2 sequences provides a comprehensive view of the bladder’s anatomy and pathology. 6 These images are examples of the T staging in the bladder. It is very important to know the differences between the invasion and non-invasion of the muscle walls. The image on the left is stage T1-stage tumour. In this image, you can see the tumour extending into the bladder, but without any involvement of the muscle layer. The tumour is confined to the inner lining of the bladder. The image on the right is a T3-stage tumour. In this tumour we can see invasion into the muscle layer. As seen in the images above, a CT can detect bladder lesions, but it is difficult to accurately assess tumour invasion using CT because it does not provide clear visualisation of the bladder layers, as MRI does. Therefore, MRI is essential for determining the T stage of the tumour. In some cases, like this example, we see a non-muscle-invasive tumour confined to the bladder. In contrast, other cases show muscle invasion, with the tumour extending beyond the bladder wall. A sessile type of lesion in MRI imaging of the bladder refers to a tumour or growth that is flat and broad-based, meaning it lacks a stalk or stem and is directly attached to the bladder wall. Unlike pedunculated tumours, which are attached by a thin stalk, sessile lesions spread more widely along the bladder surface. In the context of bladder cancer, sessile lesions can indicate more invasive or higher-grade tumours, so MRI is particularly useful for assessing the depth of invasion into the bladder wall. 7 To summarise, Ultrasound is the first imaging modality of choice for evaluating bladder pathologies. Plain X-rays are generally not useful in this context, while a voiding cystourethrogram can be helpful for assessing voiding disorders. MRI is essential for evaluating the T stage of bladder cancer, as it helps differentiate between muscle-invasive and non-muscle-invasive lesions. CT is particularly useful for staging bladder cancer, especially when the disease is present. Additionally, virtual cystography plays a valuable role in assessing certain types of bladder lesions, providing a detailed view for diagnosis. Urethra: An ultrasound is not primarily used in viewing the urethra as limitations include the size of the urethras being too small to visualise. Radiography is quite useful for imaging the urethra, especially when ultrasound has limitations in this context. Retrograde urethrography is the primary imaging modality used to evaluate the urethra, particularly in cases of traumatic injuries, inflammatory conditions, and stricture diseases of the male urethra. In addition to retrograde urethrography, sonourethrography plays an important role in assessing the thickness and length of the bulbar urethral structure. In cases involving urethral diverticula in women, voiding cystourethrography is frequently used to evaluate the condition. However, MRI is considered more sensitive in detecting these conditions and is particularly valuable for the local staging of urethral tumours. MRI provides high sensitivity and accuracy for tumour staging, similar to its use in bladder cancer evaluation. While CT is not typically suitable for imaging the urethra, MRI serves as a secondary emerging modality for urethral imaging, particularly in the context of tumour assessment. It is especially helpful for determining tumour staging, offering a non-invasive yet highly sensitive method for evaluating the extent of cancerous involvement in the urethra, much like it does for bladder tumours. Retrograde Urethrography 8 In the image on the left, we can see a fibroblastic stenosis in the urethra. The structure is highlighted by the contrast medium in the retrograde urethrogram. To better understand the cause of this type of stenosis, an MRI may be necessary for further evaluation. However, there are some pitfalls (seen on the right) to be aware of during the procedure, such as the presence of air bubbles, which can complicate the diagnosis. Therefore, it is crucial to be cautious when emptying the urethra and bladder during the study. Another example shown is vesicoureteral reflux, where contrast media flows back into the urethra during bladder voiding. This indicates reflux. Additionally, the presence of fistulas or ruptures can be detected when contrast is observed in areas where it shouldn't be, such as outside the bladder. Case Examples: 9 In this case, we have a young male who sustained a trauma. As we mentioned earlier, for traumatic injuries, the initial imaging choice is often retrograde urethrography, and upon examination, we can see something abnormal. The urethra is visible, but there is contrast media leaking outside of the urethra, indicating a possible rupture. Following this, the patient underwent a CT scan. Why was CT chosen over MRI in this situation? The reason is that the patient was in the emergency department, where CT is more readily available and quicker to organise in urgent cases. The CT scan confirmed a rupture of the urethra, specifically a bulbar urethral rupture. 10 This case involves a young male presenting with pelvic pain and fever. The patient underwent an MRI for further evaluation. In the MRI images, we can see the bladder, the pool of urine, and the intestines. The sequence shown is a T2-weighted image. Next to the urethra, there is an abnormal area that appears concerning. The hyperintense signal (bright area) on T2 near the urethra suggests something that requires further investigation, and the findings raised significant concern for a potential abscess. Prostate: Patients who undergo prostate imaging usually present with elevated PSA levels, urinary problems, or abnormal findings (like a nodule felt) during a physical examination by a urologist. Ultrasound The first choice for evaluating the prostate is ultrasound. It can be used to detect disorders within the prostate; whether the prostate is enlarged (e.g. benign prostate hyperplasia -> measurements of size are required for treatment planning) and help diagnose male infertility. There are two main approaches for this: the preferred method is transrectal ultrasound, but the transabdominal approach can also be used. Although some aspects of zonal anatomy are difficult to distinguish with ultrasound alone, we can still assess the size of the prostate and determine if it is affecting the urethra or bladder. The sovrapubic approach (similar to the bladder ultrasound technique) involves using a convex probe to study the region just above the pubic bone whilst the patient is lying down. This process is completely painless and non-invasive. The bladder should be full during this exam to help differentiate between the bladder and prostate. However, the transrectal approach provides much clearer imaging of the prostate compared to the transabdominal method. The transrectal approach provides significantly better imaging of the prostate, allowing for a more detailed assessment of different parts of the gland compared to the sovrapubic approach. Typically, the suprapubic ultrasound is used first. If any abnormalities are detected, or if the prostate is particularly large, the transrectal approach is then employed. This method offers a more accurate evaluation of the prostate volume, the capsular profile, and any 11 concerns such as detection of calcifications, ejeculatory ducts, bladder anatomy, urethral involvement within the prostate, as well as other potential issues such as constipation. For the normal sovrapubic ultrasound, we always acquire two different views: the sagittal (left) and axial (right) images. Both are essential for accurately assessing the prostate volume. In the sagittal view, we measure two diameters: the anteroposterior and longitudinal. Then, in the axial view, we measure the transverse diameter. With these three measurements, we can calculate the prostate volume. Additionally, we can evaluate the bladder just below the prostate. If the prostate appears enlarged, we ask the patient to empty their bladder and return to assess whether the bladder empties properly, which helps identify voiding issues. For the transrectal ultrasound, the images are much clearer because the probe is positioned closer to the prostate, eliminating interference from air and fat, and providing high-resolution images. This method allows us to better visualise the different layers and parts of the prostate. We use the same approach to measure the diameters as in the suprapubic view, which helps us accurately assess the prostate volume. Transrectal ultrasound also allows us to detect small hyperechoic spots, which are often calcifications, a common finding in this setting. 12 Transrectal ultrasound has significantly improved our ability to diagnose conditions in the prostate, particularly when a biopsy is needed. For patients with elevated PSA levels, the transrectal approach is the gold standard for initial assessment. While the transabdominal approach can be a good first step to assess prostate volume, it is not sufficient for diagnosing serious pathologies due to the lower quality of the images. In terms of preparation, when performing a transrectal ultrasound, we only require a small amount of urine in the bladder to avoid artefacts, so the patient is asked to empty their bladder before the exam. This contrasts with the transabdominal approach, where the bladder should be full for better imaging, and patients are usually asked to drink water about 20 minutes before the exam. Pathological conditions When assessing prostate conditions, it is crucial to first differentiate between inflammatory conditions, benign prostatic hyperplasia (BPH), and neoplastic (cancerous) conditions. Ultrasound provides fairly good sensitivity for evaluating the first two, especially in cases of benign prostatic hyperplasia, which can often be well visualised even with the transabdominal approach. However, for inflammatory conditions, a transrectal ultrasound is often necessary for a more detailed assessment. When it comes to neoplastic conditions, while ultrasound can raise suspicion of a tumour, a definitive diagnosis cannot be made using ultrasound alone, and further testing is required. 13 The left image shown above is from a transrectal ultrasound, which is evident because of the level of detail visible in the prostate gland and the circular shape of the probe, characteristic of this approach. In the images, there are several hyperechoic areas within the prostate, which are concerning. To further assess, Doppler imaging was applied, which is more effective in the transrectal approach due to the proximity of the prostate and less interference from air. Doppler showed increased blood flow within the gland, a key indicator of inflammation. This is a classic example of acute prostatitis, where the hyperechoic areas represent edema inside the gland, and the increased blood flow correlates with inflammation. Typically, patients with acute prostatitis present with pain or urinary obstruction, but in chronic prostatitis, the symptoms can be less specific. In chronic cases, we may see changes in the gland such as fibrosis, calcifications, or even enlarged lymph nodes. In more severe conditions, such as suppurative prostatitis (from things like gonorrhoea), abscesses can form, while granulomatous disease is often associated with tuberculosis. 14 The most important sign of inflammation in ultrasound is increased blood flow, making color Doppler essential for diagnosis. However, if a hyperechoic area is seen without increased blood flow, it raises suspicion of something other than inflammation. In such cases, further investigation may be needed to rule out other conditions, such as a tumour. MRI is typically the preferred modality for better assessing potential cancer in soft tissues like the prostate. Multi-parametric MRI: MRI is the preferred imaging modality for staging prostate cancer, using a combination of T1- and T2-weighted images. In a normal prostate gland, T1-weighted images show a homogeneous intermediate signal intensity, while T2-weighted images allow for better differentiation between the zones of the gland. Specifically, the anterior fibromuscular stroma appears similarly in both T1 and T2, the peripheral zone has a high signal in T2, and the central transitional zone shows a lower T2 signal. The prostatic capsule can also be visualised as a thin rim of low signal intensity. In T2-weighted MRI images, we can clearly visualise the anatomy of the prostate. Starting from the top, we first see the seminal vesicles. Moving further down, we can assess the retroprostatic angles, which are important in detecting extracapsular tumour extension in cases of prostate cancer. 15 Next, we observe the peripheral zone, which appears as a hyperintense area on T2-weighted images. This is significant because the majority of prostate cancers (about 70%) originate in the peripheral zone. We then move to the transition zone, which can sometimes appear similar to a mass on imaging, making it more challenging to assess. However, only about 23% of prostate cancers arise in this zone. Finally, we look at the external sphincter of the urethra, which allows us to evaluate whether the urethra is involved in any disease process. In the case of prostate MRI, we use a multi-parametric approach to thoroughly evaluate the prostate with different imaging sequences. This method combines morphology and functional assessment using T2-weighted images and diffusion-weighted imaging (DWI), along with dynamic contrast-enhanced MRI (DCE-MR) and specific reconstructions. These techniques help us detect the presence of angiogenesis, which is an indicator of tumour growth. Although diffusion-weighted images can be difficult to interpret visually, they are very useful because they assess the movement of water molecules within tissues. In the presence of a 16 tumour or other pathological processes, the normal movement of water is restricted, appearing as a bright area on DWI. These images do not show anatomical details but are crucial for detecting cell proliferation and cell density. A combination of T2-weighted images, which show the morphology of the gland and any lesions, with DWI and contrast-enhanced images is essential for accurately diagnosing prostate cancer. T2-weighted images help visualise the gland structure, the lesion morphology, and any extracapsular extension of the tumour. DWI confirms whether the lesion is potentially malignant, while dynamic contrast-enhanced MRI provides further precision in cancer assessment. This multi-parametric MRI approach led to the development of the PI-RADS classification in 2012, which helps us stage prostate cancer and assess the severity of the disease. As previously discussed, in T2-weighted images, the peripheral zone of the prostate typically shows high signal intensity, while cancerous areas appear as low signal intensity regions. Tumours in the peripheral zone will appear as low T2 signal areas surrounded by the high signal of the normal peripheral zone tissue. Diffusion-weighted imaging (DWI) helps detect high-risk cancers, and contrast-enhanced MRI aids in evaluating contrast kinetics, which can differentiate between cancer and inflammatory conditions. This multi-parametric MRI approach has excellent sensitivity, particularly for cancers with a Gleason score above 7. 17 The PI-RADS classification system, updated in version 2, is used to categorise prostate lesions based on their likelihood of being cancerous. PI-RADS scores range from 1 to 5. These classification systems are widely used in radiology across different organ systems. For example, there are similar systems for the breast (BI-RADS) and for coronary disease (CAD-RADS). They help standardise reporting and communication among physicians. For PI-RADS 1 or 2 lesions, we can either reassure the patient and advise no further action or recommend a follow-up with multi-parametric MRI. The negative predictive value in these cases is high, meaning we can be confident that the patient does not have cancer. However, for PI-RADS 4 or 5 lesions, the next step is usually a biopsy to confirm the presence of cancer and determine the Gleason score, which helps guide treatment decisions. 18 There are different approaches for performing a prostate biopsy. We can use the transrectal ultrasound approach, as mentioned earlier, or we can utilise MRI, or even combine both methods. The most accurate method is the MR and ultrasound fusion biopsy (targeted), where multi-parametric MRI images are fused with transrectal ultrasound to ensure precise targeting of the lesion. This approach improves the chances of obtaining a biopsy from the correct area. Additionally, there is the option of performing an MR-guided biopsy, which is typically done directly in the MRI room. For this method, either an endorectal or transrectal approach can be used, depending on the position of the lesion. In cases where the lesion is located towards the front, a transrectal needle guide is often used, with software to ensure correct positioning. Before MRI, biopsies were performed randomly using only ultrasound, meaning multiple random samples were taken from the prostate. These were often non-specific, but with modern fusion techniques combining ultrasound and MRI, biopsies can now be much more targeted, improving diagnostic accuracy and reducing unnecessary trauma for the patient. The key takeaway in the context of cancer is the importance of the PI-RADS classification system (scores 1 through 5), which helps guide the next steps in diagnosis. For PI-RADS 3 lesions, which represent intermediate risk, there are different options: we may choose to proceed with a biopsy (which would be more random if suspicion is high) or opt for MRI follow-up. The decision for PI-RADS 3 cases depends on clinical suspicion and the patient’s specific situation. Clinical Case: 19 A 63-year-old male presents with progressively rising PSA levels and urinary symptoms, including urgency, hesitancy, and a weak urine stream. The initial imaging approach is sovra-pubic ultrasound, which reveals a large, inhomogeneous prostate gland. To better assess the volume and details of the prostate, a transrectal ultrasound is performed. The transverse diameter measured by suprapubic ultrasound is 6.8 cm, whereas the transrectal approach measures it more accurately at 7.5 cm. Given the prostate enlargement and inhomogeneity, we proceed with a multi-parametric MRI. The T2-weighted images show a hyperintense peripheral zone, which is normal for this area. However, some areas in the peripheral zone appear hypointense, indicating something abnormal. One small hypointense lesion and a larger hypointense area near the capsule are seen, raising suspicion. Next, diffusion-weighted imaging (DWI) is performed. Tumours restrict water movement, and in DWI, this appears as hyperintense (bright) areas, suggesting abnormality. In this case, one lesion is very hyperintense in the DWI, while another shows less intense signal. The ADC map, which works opposite to DWI, confirms the findings by showing black areas in the corresponding suspicious regions, further indicating the presence of abnormal tissue. 20 To complete the multi-parametric MRI, contrast-enhanced MRI (T1-weighted with gadolinium) is done. This helps evaluate the contrast kinetics, which reveals increased contrast uptake in one of the suspicious lesions, further suggesting malignancy. PI-RADS Scoring: Based on the imaging findings, the two lesions are assessed using the PI-RADS classification system: The larger lesion is scored as PI-RADS 4, indicating a high suspicion of cancer. The smaller lesion is scored as PI-RADS 3, indicating an intermediate suspicion. For the PI-RADS 4 lesion, a biopsy is recommended. For the PI-RADS 3 lesion, a biopsy or follow-up could be considered, but given the findings, both areas are biopsied using fusion ultrasound and MRI guidance. The biopsy confirms Gleason 7 (T2A) prostate cancer in the larger lesion, with no lymph node involvement or metastasis, providing a favourable outlook for the patient. Testicular Diseases: Testicular Cancer Testicular cancer is relatively rare, accounting for just 1% of all neoplasms and 5% of all urological tumours. It is most commonly seen in Western societies, with a peak incidence in the third decade of life (for non-seminoma tumours, such as embryonal carcinoma), while seminomas typically affect men in their 40s (fourth decade). Although studies have been conducted to explore screening programs for testicular cancer (similar to breast cancer screenings in women), there is no strong evidence supporting such programs due to the rarity of the disease. 21 The imaging modalities used for testicular assessment are primarily ultrasound, CT, and MRI. However, radiographs have no role in this setting. Ultrasound is the first-line imaging modality and the gold standard for assessing inflammation, masses, torsion, and other pathologies. It is highly effective for identifying testicular abnormalities, including masses and inflammation. In rare cases, or for more complex conditions, MRI may be used as a secondary imaging tool to provide further detail. When we detect a testicular mass on ultrasound, we assess its location to determine whether it is intratesticular or extratesticular. Intratesticular masses are concerning and usually indicate malignancy. We measure the diameter of the testicle to ensure it falls within the normal range of 3.5 to 4.5 cm. If abnormalities are detected, the other testicle should also be examined to exclude additional lesions. In cases where the mass is difficult to assess or if there is suspicion of extratesticular extension, MRI can be used to provide a clearer evaluation. MRI is particularly helpful in situations where further characterization of the mass is needed or when there is uncertainty about the extent of the disease. Testicular Torsion Testicular torsion is one of the most challenging diagnoses in the emergency department and occurs when the testicle twists on the spermatic cord, cutting off blood supply to the testicle. This condition typically affects younger patients and causes acute testicular pain, which is the most common symptom. While the diagnosis can often be made clinically, an ultrasound is required to confirm the diagnosis before proceeding to surgery. There are two types of torsion: Extravaginal torsion: Seen primarily in neonates. Intravaginal torsion: The more common form, occurring in adolescents and young adults. The key findings on ultrasound for testicular torsion include the twisting of the spermatic cord, known as the whirlpool sign, which is pathognomonic for torsion. The torsion can be either 22 complete or incomplete, and the whirlpool sign is the most specific and sensitive indicator of torsion. Additionally, Doppler ultrasound helps assess blood flow. In cases of torsion, blood flow to the testicle may be completely absent or significantly reduced compared to the other testicle. Other important findings include enlargement of the testis and epididymis, and changes in the echotexture of the affected testicle, which becomes more heterogeneous as necrosis and edema develop. There may also be a reactive hydrocele, which is a secondary sign of torsion. The whirlpool sign is the most crucial finding to remember. It appears as a twisting of the spermatic cord on grayscale imaging, and using Doppler, you can visualise the blood flow swirling around the cord. Further Doppler examination of the testicle will reveal decreased vascularity in the affected testis, confirming the diagnosis of testicular torsion. 23