ADJUNC11VE MEDICAL KNOWLEDGE RadionuclideScrotal Imaging:Further Experience with 210 Patients Part I: Anatomy, Pathophysiology,and Methods David C. P. Chen, Lawrence E. Holder, and Moshe MelIouI The Union Memorial Hospital, and The Johns Hopkins Medical Institutions, Baltimore, Ma,yland J NuclMed24: 735—742,1983 Ten years' experience with radionuclide scrotal The parenchyma of the testis is covered by the tunica imaging (RSI) to evaluate perfusion of the scrotal con albuginea, which is composed of dense, white, fibrous tents has confirmed the value of this examination. In connective tissue. The epididymis is a comma-shaped 1973, Nadel et al. first proposed using sodium pertech structure that invests the back and upper end of the testis netate (Tc-99m) to diagnose testicular torsion (1 ). By and bulges onto its lateral surface posteriorly. the end of 1982, more than thirty articles have been The testis, epididymis, and lower end of the spermatic published on this topic (2—10),with most emphasizing cord are covered by an invaginated serous sac, the tunica the usefulness of RSI in managing patients with acute vaginalis. Its visceral layer dips between the postero scrotal pain. Two recent reviews (3,4) summarize this lateral surface of the testis and the body of the epididy experience. mis. The tunica vaginalis reflects on itself to leave the The present communication describes our findings in posterior border of the testis uncovered. This is the me 210 patients, not previously reported. There were four diastinum, through which the blood vessels and nerves groups with relatively distinct clinical presentations: (a) of the testis enter from the spermatic cord. The spermatic acutescrotalpain,(b)chronicscrotalpain,(c)scrotalcord is a fascia-covered active life line (blood, lymph, and injury, and (d) scrotal mass. The anatomic and patho nerve) that suspends the testicle in the scrotum and af physiologic bases for the scan findings will be empha fords involuntary testicular movement (with the crc sized. We discuss the staging of testicular torsion; via masteric muscle) for protection from injury and the bility of the compromised testicle; variability in the preservation of spermatogenesis (11). presentation of acute infection; anatomy of trauma, Of the three sources of blood (Fig. 1), the testicular varicocele, and inguinal hernia; and the correlation with (internal spermatic) artery provides the principal blood scrotal sonography. supply to the testis, epididymis, and tunica vaginalis. It Anatomy.Thebasicanatomyof thespermaticcord, originates from the abdominal aorta just below the renal the scrotum and its contents, and the blood vessels artery and joins the spermatic cord above the internal supplying these structures has been described in detail inguinal ring to pursue a course adjacent to the testicular (2). The relationship of the blood vessels to surface vein (pampiniform plexus) to the mediastinum. The anatomy is shown in Fig. 1. The scrotum is a cutaneous deferential artery may originate from either the inferior pouch that contains the testes and parts of the spermatic or superior vesical artery. It supplies the vas deferens, cords. The layers of the scrotum are the skin and the and near the testis, anástamoseswith the testicular ar tunica dartos, which is a highly vascular, thin layer of tery. The cremasteric (external spermatic) artery arises fibrous tissue containing elastic and smooth-muscle fi from the inferior epigastric artery at the level of the in bers (ii). The arterial supply to the scrotum (internal, ternal inguinal ring, then joins the spermatic cord. This superficial, and deep pudendal arteries) does not travel artery forms a network over the tunica vaginalis and through the spermatic cord (Fig. 2). This supply does not usually anastomoses with the testicular and deferential anastomose with the vessels supplying the testes, and arteries at the testicular mediastinum. These three yes thus cannot support testicular viability (4). sels travel through the spermatic cord (12). The veins of the spermatic cord .emerge from the ReceivedNov. 8, 1982;revisionacceptedMar. 10, 1983. mediastium to form the pampiniform plexus, which For reprints contact: Dr. David C. P. Chen, Division of Nuclear consists of three freely anastomosing groups of veins Medicine,TheJohnsHopkinsMedical Institutions,615 North Wolfe Street, Baltimore, MD 21205. (Fig. 1). The internal spermatic (testicular) vein emerges *PresentAddress:TheDepartmentofNuclear Medicine,Beilinson from the testicle and enters the vena cava. The def Hospital, Petah-Tikva,Israel. erential vein accompanies the vas deferens, draining into Volume 24, Number 8 735 CHEN, HOLDER, AND MELLOUL FIG. 1. Overview of anatomy. Relative positions of arteries andveins associated ) External Pudendal Artery with scrotum and its contents are shown, @ PudendalArtery with their relationships to scrotum and symphysis.Testicularartery Is main blood supply to testis and epididymis. veins within the pelvis. The cremasteric (external sper supplying the scrotum and its contents is small relative matic) vein follows a course along the posterior aspect to iliac or femoral artery flow. As a result, the scrotal of the spermaticcord.Inthe regionof theexternalin vessels, the dartos, and the scrotum are poorly defined guinal ring, it empties into branches of the superficial on the images of normal radionuclide angiograms and deep inferior epigastric veins and the superficial (RNA) (Fig. 3A). The relative vascularity ofthe tunica external and deep pudendal veins. The right testicular dartos, epididymis, and testis is comparable to that of vein enters the inferior vena cava obliquely below the other soft tissues (Fig. 3B). right renal vein, while the left vein enters the left renal Epididymitis is the most common disease involving the vein at right angles (12) (Fig. I). scrotum or its contents. Secondary to the inflammatory Physiologicand pathophysiologicbasis for scrotal changes in the epididymis, markedly increased perfusion scanning. The blood volume passing through the vessels through the spermatic cord vesselsand to the epididymis is noted in the RNA. In classic acute epididymitis, hy peremia occurs in the head, body, and tail of the epidi dymis. If confined to a small area of the epididymis, focal hyperemia occurs only in the infected part, and the total increased perfusion through the vessels of the spermatic cord is so small that it may not be visible on the RNA. If the inflammatory process spreads to the testis, it is called epididymo-orchitis. In general, the degree of hy peremia is related to the duration and stage of illness. The more diffuse and acute the illness is, the more in tense the hyperemia and swelling of the scrotal contents. Delay or inappropriate antibiotic treatment may lead to progression and extention of the infection and result in tissue destruction, and/or abscess formation. In these cases there is markedly increased perfusion not only through the vessels of the spermatic cord, but also FIG.2. Vascularanatomy,lateralview.Pudendalarteryislocated through those outside it, such as the external and internal posteriorly,separatedfrom spermaticcord. Moreanteriortesticular, cremasteric, and deferential arteries pass through spermatic pudendal arteries, which supply the dartos. Hyperemia cord. is noted in the dartos and throughout the hemiscrotum. 736 THE JOURNAL OF NUCLEAR MEDICINE ADJUNCTIVE MEDICAL KNOWLEDGE •:@ @ (@F @\(;;T@ ( 4,@(5Y8@1 2 3 FIG. 3. Normal study. Radionuclide an giogram (upper): Activity in iliac (I) and femoral (F) arteries appears on sides of images.There Is no definition of testicular or deferential vessels (T), which pass through spermatic cord, or pudendalyes sels (P) which lie outside cord. No sig nificantactivItyIsseenin scrotalregion(S). (1) 0—5sac, (2) 6—10,(3) 11—15,(4) 16—20, (5) 21—25,(6)26—30.Scrotal image(lower left): Testicular activity (T) is symmetrical andslightlymore intensethanthighactivity (Th).Minimalasymmetryin size is normal. Lead-shieldedImage(lower right). Curved arrow Indicates edge of lead interposed between scrotum and thigh. Thigh “shine-through―Is eliminated. A photopenic area, reflecting the lack of blood in the torsion), there is progressive edema, congestion, and necrotic center of an abscess, is often visible. hemorrhage, with reactive hyperemia and erythema. Testicular torsion, whose anatomy has been described Increased dartos perfusion is through the pudendal ar (2), is more accurately referred to as torsion of the teries rather than the vesselsof the spermatic cord, which spermatic cord. For torsion to occur, there must be a are occluded. congenital abnormality of the tunica vaginalis that will In the late phase of torsion (more than 24 hr following allow excessive mobility of the testis (13). torsion), infarction usually occurs. There is significant When the spermatic cord is twisted, the veins in the swelling and scrotal hyperemia. Increased perfusion cord are quickly obstructed due to their thin, easily occurs through the pudendal artery, and when this is seen compressed walls (14). Because of the tough connective on the scan, in association with halo-like hyperemia of tissue surrounding the spermatic cord, the swollen veins the dartos, it should never be confused with increased can produce sufficient pressure to shut off arterial flow, perfusion through the arteries of the spermatic cord to even if the twist itself has failed to occlude the artery an inflamed epididymis or to an abscess. (15). Initially