Genitourinary Imaging
Original Research
Contrast-Enhanced Ultrasound in the Evaluation of Focal Testicular Complications Secondary to Epididymitis
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OBJECTIVE. The purpose of this study is to determine the effectiveness of contrast-enhanced ultrasound in evaluating incidental focal testicular lesions in epididymitis.
MATERIALS AND METHODS. Intratesticular lesions ipsilateral to epididymitis were subject to B-mode color Doppler ultrasound and contrast-enhanced ultrasound, with their appearances reviewed in consensus. Final interpretation was by histologic analysis or follow-up ultrasound.
RESULTS. Over 28 months, 16 focal testicular lesions (median lesion size, 24 mm; range, 14–48 mm) in 14 patients (median age, 49 years; range, 18–81 years) were examined. Lesions were oval (n = 14), wedge shaped (n = 1), or involved the entire testis (n = 1). Lesions were isoechoic (n = 1), hypoechoic (n = 4), or of mixed echogenicity (n = 11). Color Doppler ultrasound flow was not clearly depicted in 13 lesions but was present in three lesions, with contrast-enhanced ultrasound concordant with color Doppler ultrasound, showing unequivocal absence of vascularity and increased flow, respectively. In the avascular lesions, rim enhancement (n = 6), vascular projections (n = 4), and irregular (n = 10) and smooth (n = 2) borders were documented. The observers identified infarction (n = 9), abscess (n = 4), orchitis (n = 1), and tumor (n = 2). Histologic examination (seven lesions in five patients) confirmed infarction, abscess formation, and seminoma; follow-up ultrasound confirmed resolution for eight patients.
CONCLUSION. Contrast-enhanced ultrasound is a useful adjuvant to color Doppler ultrasound examination of a focal lesion in the testis ipsilateral to epididymitis to improve the characterization of nonvascularized tissue.
Keywords: contrast-enhanced imaging, color Doppler, infarction, testis, ultrasound
Any focal testicular abnormality in the presence of epididymitis on an ultrasound examination presents a dilemma: either a focal excision biopsy or an orchidectomy may be required to exclude an underlying tumor mimicking acute inflammation, which is reported to occur in up to 1.3% of patients with epididymitis [1]. A number of tumor mimics occur in the presence of epididymitis, including focal orchitis, which is a consequence of spread of infection from the adjacent epididymitis [2]; venous infarction, which occurs when testicular and epididymal edema produces venous impairment; progressive ischemia; and focal or global areas of infarction [3–6]. Eventually, infarction leads to necrosis and the development of an intratesticular abscess [7]. Histologic evaluation of epididymitis-induced testicular infarction has established this as a consequence of venous thrombosis [8].
In focal orchitis, the ultrasound appearances are varied but may appear heterogeneous as a diffuse low-reflectivity testis with pockets of altered reflectivity. Color Doppler ultrasound reveals increased vascularity in the early stages or its absence in the later stages [2]. In venous infarction, ultrasound may show a variable appearance, from a focal mass to diffuse alteration in reflectivity, with reduced vascularity on color Doppler ultrasound [5, 6]. An intratesticular abscess may show irregular walls, low-level internal echoes, and a hypervascular margin [7]. Confidence in the absence of vascularity on color Doppler ultrasound would facilitate the diagnosis of infarction or abscess, allowing differentiation from an increase in vascularity present with tumors [9, 10] or focal orchitis [2]. Typically, a benign avascular lesion resolves or contracts on serial examinations, whereas a tumor retains vascularity and enlarges [11, 12]. A watchful waiting policy may not be appropriate in the presence of a primary testicular tumor [12, 13].
Contrast-enhanced ultrasound is used widely in Europe and Asia and is established in cardiac and hepatic diseases [14], with applications in other organ systems gaining recognition [15]. Contrast-enhanced ultrasound has a proven safety record, comparable to that for contrast agents used in MRI [16]. Its use in vascular diseases, the original application, is often deployed to niche areas, such as transcranial Doppler examinations with a proven role in Doppler rescue [17], when, if the signal on the color Doppler ultrasound examination is suboptimal, contrast-enhanced ultrasound may substantially improve the signal return and ascertain the presence of the vascular supply. The application of this Doppler rescue technique can be advantageous in the testis, where the detection of vascular flow is crucial to establishing a diagnosis.
We have applied contrast-enhanced ultrasound in a series of patients presenting with continuing scrotal symptoms in the presence of epididymitis, who, on the baseline B-mode ultrasound and color Doppler ultrasound studies, were identified with focal testicular abnormalities to establish the effectiveness of contrast-enhanced ultrasound in increasing diagnostic confidence and facilitating correct patient management.
| Materials and Methods |   |
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Approval to report this retrospective study was sought from our hospital’s ethics board, which waived the need for formal review and approval. All patients gave informed consent for a contrast-enhanced ultrasound examination.
All the ultrasound examinations were performed by two operators with experience (15 and 10 years) in the techniques of testicular ultrasound and the use of microbubble contrast agents. The standard examination for a testicular ultrasound was performed in accordance with department protocol, using the optimal high-frequency transducers normally used in small-parts imaging, to record the initial findings. Patients were then imaged using high-frequency linear-array transducers with microbubble contrast capabilities on scanners with a 15L8w transducer (n = 5; Acuson Sequoia 512, Siemens Healthcare) or with a 9L4 transducer (n = 9; S2000, Siemens Healthcare). Once the optimum B-mode and color Doppler parameters were set for each patient, B-mode and color Doppler ultrasound images of the focal intratesticular lesion under investigation were recorded. Cine loops were routinely acquired, with additional B-mode and color Doppler ultrasound views obtained as necessary. The images were stored for later review on a PACS (Centricity, GE Healthcare).
Microbubble contrast agent (SonoVue, Bracco) was used for the contrast-enhanced ultrasound studies. Each patient received a 4.8-mL dose of SonoVue, which was administered as an IV bolus injection via a 20-gauge cannula inserted into the antecubital fossa and was flushed with 10 mL of normal saline. For the contrast-enhanced ultrasound examinations, the examiner held the transducer over the area of examination while an assistant administered the microbubble contrast agent, observing the arrival of the microbubble contrast and continuing to observe the lesion until the disappearance of microbubble contrast or for 90 seconds, whichever was the earlier. The technique used for contrast-enhanced ultrasound imaging was the conventional low-mechanical-index imaging used for contrast-enhanced ultrasound examinations in our department (Cadence Contrast Pulse Sequencing, Siemens Healthcare). All the ultrasound systems used had the capability of dual-screen display of the fundamental B-mode image side by side with the contrast-enhanced ultrasound image to allow the operator to maintain the lesion in question within the FOV during the entire examination. The contrast-enhanced ultrasound examinations had cine loops recorded for a minimum of 90 seconds, either continuously or as multiple short 5-second periods as required. The images were stored for later review on the PACS.
Cases were selected for review from the Ultrasound Department’s database of testicular ultrasound examinations, which included patients who underwent a testicular contrast-enhanced ultrasound examination. Over a period of 28 months (2008–2011), when contrast-enhanced ultrasound was introduced for testicular ultrasound in our department, patients were identified and selected from this database if some or all of the following criteria were satisfied: the clinical history (scrotal pain and swelling, penile discharge, or dysuria) and examination (tenderness, erythematous, swollen hemiscrotum, and a thickened epididymis) were in keeping with epididymitis; B-mode and color Doppler ultrasound findings were consistent with a diagnosis of epididymitis; an incidental intratesticular lesion was identified; ultrasound follow-up confirmed lesion regression or the absence of progression; histologic examination confirmed an area of tumor, infarction, or abscess; and resolution on clinical examination.
All images were reviewed by the two observers who had not performed the examinations (both with 6 years’ experience with contrast-enhanced ultrasound) to reach a consensus view on the following features: lesion position within the testis (peripheral or central), lesion characteristics on B-mode (echogenicity and homogeneity), lesion size (diameter in three planes was measured using the ultrasound machine’s internal calipers, and the largest measurement was used to determine maximum lesion size), lesion shape on B-mode and on contrast-enhanced ultrasound (rounded or wedge shaped), lesion border delineation on B-mode and on contrast-enhanced ultrasound (well defined or poorly defined, and smooth or irregular), presence of vascularity in the lesion on color Doppler ultrasound (absent, increased, or decreased in comparison with adjacent normal testicular tissue), evidence of lesion wall abnormality (irregularity, enhancement, and septations), and presence and pattern of contrast-enhanced ultrasound enhancement in the lesion, including the observation of intralesion projections, rim enhancement, and border delineation.
In addition, the side (right or left), presenting symptoms, and patient age were recorded. Any additional findings on B-mode and contrast-enhanced ultrasound examinations were recorded. The final diagnosis was made with histologic examination or evolution of the appearance on follow-up ultrasound.
| Results | |
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Over the 28-month period, 14 patients met the criteria for a focal intratesticular lesion in the presence of epididymitis, and 16 lesions were identified (one patient had three separate lesions in the affected left testis). All of the patients presented with scrotal pain with a clinical history consistent with epididymitis of varying duration (range, 1–56 days), and a finding of epididymitis was confirmed on ultrasound in all patients. The median age of the patients was 49 years (range, 18–81 years). The right testis was affected in three and the left testis in 11 of the 14 patients. The results are summarized in Table 1.
Characteristics of the 16 lesions on B-mode and color Doppler ultrasound were as follows: first, 10 lesions were central within the testis (Figs. 1A, 1B, and 1C), five lesions were peripheral (Figs. 2A, 2B, 2C, and 2D), and the entire testis (global) was affected in one patient (Figs. 3A, 3B, and 3C). Second, the median measured diameter of the lesions (n = 15, excluding the global abnormality) was 24 mm (range, 18–48 mm). Third, 14 lesions were rounded and one was wedge shaped; the entire testis was involved in one patient. Fourth, the echogenicity was low in four lesions, isoreflective in one lesion, and mixed reflective in 11 lesions. Fifth, on B-mode ultrasound, eight lesions had well-defined borders (including the global abnormality), and eight lesions had poorly defined borders. Sixth, 13 lesions showed an absence of color Doppler signal on the color Doppler ultrasound examination. The color Doppler ultrasound examination was unable to reveal clear demarcation between vascularized and nonvascularized areas and was unable to characterize the margins of the lesion. Finally, three of 16 lesions showed increased vascularity within the lesion on color Doppler ultrasound; one lesion showed a benign manner (linear intralesion vessels) and two lesions showed a malignant manner (chaotic intralesion vessels).
TABLE 1: Patient Details, Ultrasound, Surgical, and Histologic Findings in 14 Patients With Focal Testicular Lesions Ipsilateral to Epididymitis
 View larger version (132K) | Fig. 1A—69-year-old man with left testicular hemorrhagic venous infarction on histologic examination; lesion was centrally located (patient 1). A, B-mode examination shows evidence of severe epididymitis (long arrow) with markedly thickened epididymis and scrotal wall. Central rounded abnormality (star) of mixed echogenicity is present. There is poor border definition of abnormality (short arrows). |
 View larger version (102K) | Fig. 1B—69-year-old man with left testicular hemorrhagic venous infarction on histologic examination; lesion was centrally located (patient 1). B, Color Doppler image shows color flow (arrow) surrounding central avascular mixed echogenic lesion. |
 View larger version (148K) | Fig. 1C—69-year-old man with left testicular hemorrhagic venous infarction on histologic examination; lesion was centrally located (patient 1). C, Contrast-enhanced ultrasound image was obtained using dual-screen facility, with mechanical index of 0.12, at 25 seconds after contrast agent administration. Image shows complete absence of enhancement within lesion (star), smooth well-delineated regular border (short arrows), and rim enhancement (long arrows). |
 View larger version (130K) | Fig. 2A—42-year-old man with left testicular abscess (peripherally located lesion) on follow-up ultrasound (patient 11). A, B-mode examination shows ill-defined peripherally located rounded mixed echogenic abnormality (arrows). |
 View larger version (109K) | Fig. 2B—42-year-old man with left testicular abscess (peripherally located lesion) on follow-up ultrasound (patient 11). B, On color Doppler image, there is no vascular flow to central aspect (arrow) of abnormality. |
 View larger version (133K) | Fig. 2C—42-year-old man with left testicular abscess (peripherally located lesion) on follow-up ultrasound (patient 11). C, Contrast-enhanced ultrasound image was obtained using dual-screen facility, with mechanical index of 0.10, at 37 seconds after contrast agent administration. Lesion is avascular, with irregular borders, vascular projections (short arrows), and rim enhancement (long arrow). |
 View larger version (127K) | Fig. 2D—42-year-old man with left testicular abscess (peripherally located lesion) on follow-up ultrasound (patient 11). D, Follow-up ultrasound examination at 4 weeks. Contrast-enhanced ultrasound image was obtained using dual-screen facility, with mechanical index of 0.10, at 35 seconds after contrast agent administration. Only subtle low reflective abnormality (arrows) is present at site of previously documented abnormality with normal enhancement with contrast. |
 View larger version (96K) | Fig. 3A—74-year-old man with left testicular global infarction on histologic examination (patient 14). A, Entire testis is isoechoic, with evidence of epididymal enlargement (short arrows) and septated hydrocele (long arrow). |
 View larger version (110K) | Fig. 3B—74-year-old man with left testicular global infarction on histologic examination (patient 14). B, On color Doppler image, there is some color Doppler signal outside testis but no color signal is present within testis (arrow). |
 View larger version (133K) | Fig. 3C—74-year-old man with left testicular global infarction on histologic examination (patient 14). C, Contrast-enhanced ultrasound image was obtained using mechanical index of 0.08, at 80 seconds after contrast agent administration. There is no enhancement of testis (star), with marked enhancement of epididymis, which displays two small abscesses (arrows) not seen on unenhanced images. |
 View larger version (136K) | Fig. 4A—81-year-old man with left testicular abscess on histologic examination (patient 6). A, Poorly defined mixed echogenic lesion (short arrows) and septated hydrocele (long arrow) are seen. |
 View larger version (120K) | Fig. 4B—81-year-old man with left testicular abscess on histologic examination (patient 6). B, Color Doppler image shows absence of color Doppler flow to abnormal lesion (arrow). |
 View larger version (138K) | Fig. 4C—81-year-old man with left testicular abscess on histologic examination (patient 6). C, Contrast-enhanced ultrasound image was obtained using dual-screen facility, with mechanical index of 0.12, at 50 seconds after contrast agent administration. Lesion is avascular, with irregular borders, vascular projections (short arrows), and rim enhancement (long arrows). |
After the administration of microbubble contrast agent, there was no significant lesion flow on contrast-enhanced ultrasound for 12 of 16 lesions, and the entire testis was nonenhancing in one patient. There was a peripheral rim of hyperenhancement in six lesions. All 12 of the avascular focal lesions were round. The definition of the internal border of the avascular focal lesions (n = 12) was well-delineated and smooth in two lesions and well-delineated and irregular in 10 lesions, with vascular projections into the lesion in five cases. Enhancement with contrast-enhanced ultrasound was observed in three lesions, two in a malignant manner (chaotic intralesion vessels) and early washout of enhancement, and one in a benign manner (linear intralesion vessels).
Focal lesions with no vascularity on contrast-enhanced ultrasound (n = 12) were identified as either infarctions (n = 8) or abscesses (n = 4). Of the eight infarctions, seven had sharply defined irregular border, one had a sharply defined regular border, and three had septations. Of the four abscesses, three had sharply defined irregular borders, one had a sharply defined regular border, and two had septations. The diagnoses by the independent observers were infarction in nine of 16 lesions, including the global infarcted testis (Figs. 3A, 3B, and 3C), abscess formation in four lesions (Figs. 4A, 4B, and 4C), one focal orchitis (Figs. 5A, 5B, 5C, and 5D), and two focal tumors (Figs. 6A, 6B, 6C, 6D, and 6E).
Five patients underwent orchidectomy, with symptoms of pain deemed intractable despite optimal treatment. Infarction was confirmed in four patients, in concordance with the observers’ interpretation of the ultrasound findings. One patient had a fungal abscess mis-interpreted as an infarction. One patient also had two germ cell tumors (seminomas) on the excised specimen that were correctly identified on the color Doppler ultrasound and contrast-enhanced ultrasound examinations as vascularized lesions separate from the area of focal infarction. The patient with a global testicular infarction was found to have two epididymal abscesses on contrast-enhanced ultrasound that were not present on the B-mode examination. Eight patients had a follow-up ultrasound examination with full or partial resolution in all cases (abscess [n = 3], infarction [n = 4], and orchitis [n = 1]) over 4–52 weeks. One patient was lost to follow-up.
 View larger version (153K) | Fig. 5A—55-year-old man with left testicular focal orchitis (patient 10). A, There is well-demarcated low-echogenic rounded abnormality (arrows) at upper aspect of left testis. |
 View larger version (112K) | Fig. 5B—55-year-old man with left testicular focal orchitis (patient 10). B, Color Doppler image confirms vascularity in lesion, with blood vessels showing linear pattern (arrows) conforming to normal testicular vascular pattern. |
 View larger version (73K) | Fig. 5C—55-year-old man with left testicular focal orchitis (patient 10). C, Contrast-enhanced ultrasound image was obtained using dual-screen facility, with mechanical index of 0.18, at 35 seconds after contrast agent administration. There is uniform vascular enhancement throughout lesion (arrow), with no evidence of malignant type of circulation, in keeping with area of focal orchitis. |
 View larger version (126K) | Fig. 5D—55-year-old man with left testicular focal orchitis (patient 10). D, Follow-up ultrasound examination shows altered echogenicity (arrow) at upper aspect of left testis. |
| Discussion | |
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Establishing intratesticular lesion vascularity is vitally important and may be difficult with conventional ultrasound techniques; increased vascularity suggests malignancy, and its absence suggests a benign abnormality, unless increased vascularity is present in an area of focal orchitis [10, 18]. Ultrasound combined with color Doppler ultrasound remains inhibited by a number of factors, including operator experience, technical limitations, and the inability to transform a dynamic operator-dependent examination into a form that may be appreciated by the referring physician. Patients who present with an indeterminate lesion of the testis will often require definitive diagnosis with either excision biopsy or even orchidectomy [19]. Although, in this study, color Doppler ultrasound with experienced operators was accurate in depicting the abnormality, contrast-enhanced ultrasound allowed exquisite visualization of vascular enhancement; paradoxically, it is the absence of enhancement in avascular lesions that is so striking that a definitive interpretation is ensured. The absence of flow occurs in an infarction or abscess of the testis [20–22].
In the current series of patients with abnormalities of the testis in the presence of epididymitis, we have shown the usefulness of contrast-enhanced ultrasound to delineate the abnormality and to unequivocally indicate the absence of a vascular supply to a focal abnormality. This was found in both testicular venous infarction and intratesticular abscess formation, although the absolute differentiation between these two entities remains difficult with all ultrasound techniques. Nevertheless, a confident assessment of the absence of vascularity within any testicular lesion on contrast-enhanced ultrasound allowed the correct clinical management pathway to be instituted. Moreover, we have shown that the appearances of testicular venous infarction and abscess formation assumes a more rounded appearance, which helps to differentiate this entity from a true arterial wedge-shaped infarction, typically described as a segmental infarction [12, 20]. The three lesions with vascularity were all correctly interpreted as tumor and orchitis on both color Doppler and contrast-enhanced ultrasound. Contrast-enhanced ultrasound was able to confidently differentiate two focal tumors from a focal infarction in the same testis, facilitating the correct management.
 View larger version (140K) | Fig. 6A—37-year-old man with left testicular venous infarction and two seminomas on histologic examination (patient 5). A, There is well-demarcated low-echogenic lesion (long arrow) in upper aspect of left testis and further poorly defined mixed-echogenic lesion (short arrows) in central aspect of testis (second low-echogenic lesion not shown). |
 View larger version (109K) | Fig. 6B—37-year-old man with left testicular venous infarction and two seminomas on histologic examination (patient 5). B, On color Doppler image, there is no color Doppler signal to larger mixed-echogenic lesion (star), with some color Doppler flow present in partly seen low-echogenic lesion (arrow). |
 View larger version (105K) | Fig. 6C—37-year-old man with left testicular venous infarction and two seminomas on histologic examination (patient 5). C, On color Doppler image, there is increased color Doppler flow to two low-echogenic lesions (arrows). |
 View larger version (77K) | Fig. 6D—37-year-old man with left testicular venous infarction and two seminomas on histologic examination (patient 5). D, Contrast-enhanced ultrasound image was obtained using dual-screen facility, with mechanical index of 0.18, at 33 seconds after contrast agent administration. Two low-echogenic lesions (arrows) show increased enhancement following administration of contrast agent. |
 View larger version (76K) | Fig. 6E—37-year-old man with left testicular venous infarction and two seminomas on histologic examination (patient 5). E, Contrast-enhanced ultrasound image was obtained using dual-screen facility, with mechanical index of 0.18, at 45 seconds after contrast agent administration. There is absence of enhancement within mixed-echogenic lesion, with sharply demarcated border (long arrow) and vascular projections (short arrows) noted. |
In the present series, when an avascular focal lesion was revealed with contrast-enhanced ultrasound, wall morphology differentiated the abnormality from normal testicular tissue. This clear definition of the extent of devitalized tissue allowed an estimate of the viability of the imaged testis. Both abscess formation and venous infarction had irregular borders, rim enhancement, and vascular projections after contrast-enhanced ultrasound, which would explain the difficulty the independent observers encountered in being able to differentiate between abscess and infarction, although they consistently identified a benign abnormality. This is likely a reflection of the underlying pathologic process, where progression of ischemia to infarction and eventual infection occurs. We did not follow up the patients with a contrast-enhanced ultrasound examination to document the natural course of the rim enhancement and vascular projections, but evaluation of contrast-enhanced ultrasound in a series of patients with acute segmental infarction showed resolution of the rim enhancement over time [20].
The interesting finding in the current series of patients with testicular infarction and abscess formation secondary to epididymitis is the morphology of the area of abnormality. The suggested mechanism of infarction in these cases is secondary to edema and venous congestion, rather than a compromise to the arterial supply. Previous studies have suggested that epididymitis contributes to arterial segmental infarction and have detailed the different appearances, ranging from wedge-shaped to a more rounded shape [12, 13]. However, with the clear depiction of the abnormality on contrast-enhanced ultrasound and the unequivocal history of epididymitis, the pathophysiology of venous infarction is distinct from that arising as a consequence of arterial compromise. We would suggest that segmental testicular infarction arising from an arterial compromise has different causes and is likely to produce an ultrasound pattern different from that of a venous infarction produced by epididymitis. A venous infarction will be more rounded, and an arterial infarction will be wedge shaped; this may be clearly depicted on a contrast-enhanced ultrasound examination [20]. There is a reasonable rationale for the differentiation of venous and arterial infarction based on the anatomy of the arterial supply and venous drainage. Venous congestion is more likely to result in a focal area of infarction within the center of the testis, where the risk of ischemia is greatest, as seen in the present series with the majority of the areas of infarction centrally located in the testis. Vascularized projections extending from the periphery of the lesion may represent residual arterioles, which have been apparently “skeletonized” as a result of infarction of the adjacent testicular parenchyma, as seen in the current case series. There are suggestions that edema of the epididymis may compress the testicular artery, resulting in a torsionlike picture, with global infarction of the testis as seen in one of our patients, but this must be a rare occurrence [4, 23].
The use of contrast-enhanced ultrasound for the investigation of scrotal abnormalities is a relatively new field, and there has been a significant learning curve to identify different vascular patterns of enhancement [21, 22, 24]. With experience now gained, we are confident that the lack of enhancement is a good marker for the absence of vascularity, whether in infarction, abscess formation, or benign lesions, such as an epidermoid cyst [25]. Some authors suggest that MRI would be useful in depicting areas of segmental infarction in the testis [13], but we have previously advocated the sole use of color Doppler ultrasound in diagnosing this entity and now propose the use of contrast-enhanced ultrasound as an even more effective imaging technique [12].
There is now accumulated experience with the use of microbubble contrast agents in body imaging, particularly in the areas of liver, cardiac, and renal disease [14]. The microbubble contrast agent works well in regions of the body when a transducer frequency of 3 MHz or less is used, with the size of the microbubbles rather fortuitously allowing the best resonance and subsequent detection at this frequency. Consequently, the dose used is normally 2.4 mL in liver imaging and even 1.2 mL in renal imaging. With the higher frequencies used in the imaging of the testis, often greater than 10 MHz, the microbubbles do not resonate efficiently, and a dose of 4.8 mL of microbubble contrast agent was found to allow better enhancement, although other groups have used 2.4 mL with good results. In a study of acute testicular pain, Valentino et al. [21], using 4.8 mL of microbubble contrast agent, evaluated patients with tumors, infarctions, torsion, and trauma and identified increased enhancement in focal tumors, reduced enhancement in testicular fractures, and infarctions, similar to the findings in the current study. Lock et al. [22] adequately identified enhancing tumors in the testis using a dose of 2.4 mL of microbubble contrast agent. Contrast-enhanced ultrasound using a dose of 4.8 mL of microbubble contrast agent was found to be useful in estimating the extent of tissue viability in trauma to direct organ-sparing surgery [26].
There are several limitations to this case series. A small number of patients were identified, but this reflects the rarity of this condition, and it may be that with the use of contrast-enhanced ultrasound, venous infarction and abscess formation in the presence of epididymitis will be more frequently identified. Only five patients had a histologic diagnosis, whereas the majority of the patients underwent ultrasound follow-up. However, the meticulous recording of the clinical history and documentation of evolutionary changes on follow-up ultrasound generally confirmed the benign nature of the diagnoses.
In conclusion, we have shown the clear depiction of areas of infarction and abscess formation in the testis on contrast-enhanced ultrasound, distinguishing these benign areas from potentially malignant tumors. Our findings also suggest that venous infarction and abscess formation more often present as centrally located rounded areas, which may be a complication of epididymitis, distinct from an arterial wedge-shaped segmental infarction, a theory that is supported by testicular anatomy and the expected natural history of the condition. Contrast-enhanced ultrasound provides excellent and unrivalled visualization of parenchymal and vascular enhancement and may be used in combination with B-mode color Doppler ultrasound and clinical history to facilitate an accurate diagnosis, thus preventing unnecessary surgery and orchidectomy.
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