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 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 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 groups with relatively distinct clinical presentations: (a) of the testis enter from the . The spermatic acutescrotalpain,(b)chronicscrotalpain,(c)scrotalcord is a -covered active life line (blood, lymph, and injury, and (d) scrotal mass. The anatomic and patho ) that suspends the in the 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 (11). presentation of acute infection; anatomy of trauma, Of the three sources of blood (Fig. 1), the testicular , and inguinal hernia; and the correlation with (internal spermatic) provides the principal blood scrotal sonography. supply to the testis, epididymis, and tunica vaginalis. It Anatomy.Thebasicanatomyof thespermaticcord, originates from the abdominal 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 () 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 , 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 ) 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 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 . 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 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 , 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 , which supply the dartos. Hyperemia cord. is noted in the dartos and throughout the hemiscrotum.

736 THE JOURNAL OF NUCLEAR MEDICINE ADJUNCTIVE MEDICAL KNOWLEDGE

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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 this leadsto edemaandcongestionof the A hydrocele is a collection of fluid between the layers compromised testicle, which is then followed by hem of tunica vaginalis. Normally a very small amount of orrhage, and finally infarction (16). Since there is no fluid is produced, kept in equilibrium by removal via perfusion to the testicle, a photopenic defect is seen in the lymphatics in the parietal layer of the tunica. A primary scrotal images. The developing edema, congestion, or hydrocele results from a defect in lymphatic drainage, hemorrhage progressively increase the defect seen in the with accumulation offluid (17). Secondary hydroceles scrotal scan. Hemorrhage and infarction of the testicle are associated with a variety of lesions, including in may induce inflammatory reaction in the surrounding flammatory disease, trauma, testicular tumor, acute highly vascular tissue of the tunica dartos. The longer testicular torsion, and scrotal surgery. Hydrocele fluid the testicle has been ischemic the worse the hemorrhage does not freely communicate with the vascular spaces and infarction will be. As the severity of hemorrhage and and appears as a photopenic area (photon attenuation) infarction increases, so does inflammation, with its in in the scrotal scan. creased tracer activity in the dartos. A varicocele is an abnormal dilation and tortuosity of In the early phase of acute torsion (less than 5 to 7 hr the veins of the pampiniform plexus within the scrotum after onset of symptoms), there is minimal edema or (Fig. 4). As shown in Fig. I, the three venous systems congestion, and only minimal or no reactive hyperemia draining the scrotum are the internal spermatic vein, in the dartos. vasal vein, and cremasteric vein. These systems are In the midphase of acute torsion (7 to 24 hr following normally provided with valves, which may become in

Volume 24, Number 8 737 CHEN, HOLDER,AND MELLOUL

FiG.4. Anatomyof varicocele.Locatedwithinscrotum,a varicocele Tunica Vaginalis consistsof dilatedandtortuousveinsof pampiniformplexus(a@row). Internalspermatic(testicular)vein, cremasteric(externalspermatic) FiG.5. Anatomyof Inguinalhemla.Inthisschematicrepresentation, vein, and deferential (yasal)vein, are illustrated. prolapse of intestine througha patent processusvaginalis fills p0- tential space between layers of tunica vaginalis. competent, permitting the retrograde passage of blood and formation of the varicocele (18). Ninety-nine per tunica vaginalis (Fig. 6, right). If the parietal layer of the cent of all are on the left side. The right tunica is lacerated, the blood can dissect into the groin angled termination of the left renal vein, compression of and perineal area (/4,22). the left renal vein between the aorta and superior mes Testicular tumors are the most common neoplasms enteric artery, and the presence of adrenalin-laden blood in man between ages 20 and 35. These tumors are most intheleftrenalvein(19),haveallbeenadvancedas often of germ-cell origin (23). The germ cell can be explanations for this asymmetrical incidence. When the differentiated into four basic patterns: seminoma, em varicocele is of sufficient size, the RNA demonstrates bryonal carcinoma, teratoma, and choriocarcinoma, and a venous-phase accumulation of tracer in the scrotum, the tumors often contain mixtures of these four types. and this is also seen in the scrotal scan. The clinical behavior of these combinations depends lnguinal hernia results from a prolapse of intra-ab more on the most malignant element present rather than dominal contents, most often the intestine, into a patent the predominant element (24). Clinical presentations processus vaginalis (Fig. 5). The processus is a finger-like are variable and often misleading. Both the RNA and projection of that accompanies the testicle scrotal scan reflect the relative vascularity of tumor as it descends into the scrotum. It is patent in almost all histology. newborns, 60% of 1-yr-olds, and 20% of adult males at autopsy (20). Predisposing factors or specific causes for MATERIALS AND METHODS the development of an inguinal hernia are uncertain. Hernias are ten times more common in boys than in men, Patientpopulation.FromJune1976throughOctober presumably due to a larger processus. They occur more 1981, 243 patients had testicular RNAs and scrotal often on the right side than on the left, and about 10% scans. Final diagnoses were obtained surgically in 72 are bilateral (21 ). In the RNA, perfusion through vessels cases. In another 138 cases, diagnoses were determined both within and outside of the spermatic cord is not in by a clinical follow-up of at least 6 mo. These 210 pa creased, and no abnormalities of scrotal perfusion are tients (246 scans) formed the data base of this report. seen. In the scrotal scan, the herniated intestine results The remaining 33 patients did not return to the referring in photon attenuation extending from the inguinal region physician or failed to schedule follow-up visits as in to the hemiscrotum. structed by the emergency room staff. They are excluded The pathophysiology of scrotal trauma has been re from our study. The age range of the patients was 6 to viewed recently (3) and will be only briefly discussed. 82 yr. The complete distribution is shown in Fig. 7. With mild trauma, capillary bleeding within the testicle's Clinically, these patients presented with: friable parenchyma can produce subcutaneous capillary I. Acute scrotal pain (109 cases). We define this bleeding in the dartos, as well as a small intratesticular as pain with rapid (often sudden) onset, usually hematoma (Fig. 6, left). With severe trauma, rupture occurring within the previous 24 hr, but occasion of the can occur, leading to a hemato ally up to five days before presentation. Scrotal cele, which is a collection of blood between the layers of swelling often accompanies the pain.

738 THE JOURNAL OF NUCLEAR MEDICINE AI)JUN('TIVI MIDRAL KNOWLIDil

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Tunica Vaginalis FIG.6. Trauma.Intratesticularhematomaislocatedwithinfriableparenchymaoftesticle(left).Hematoceleiscollectionofbloodbetween the layers of tunica vaginalis (right).

2. Subacute scrotal pain (25 cases). This is pain 5. Others (three cases). Inflammation of the lasting in excess of five days. It may be intermit spermatic cord (n = I ) and testicular atrophy (n tent, or may have begun as an acute episode for = 2) are included here. which the patient did not seek medical attention. Technique. The basic procedure is similar to that Some patients were treated for scrotal pain or previously described (2). After orally administering 0.4 swelling, but had not recovered. Others had a to I .0g potassiumperchlorate(in aqueoussolution), the more chronic history of pain. patient is placed supine. The is taped up over the 3. Scrotal mass (56 cases). To be included in this pubis and the scrotum is arranged parallel to the face of group, the primary complaint was the presence of the low-energy converging collimator using a “tape a mass. Most patients had no associated pain, but sling―or towel support (Fig. 8, upper left). A symmet mild, often intermittent pain was present in some rical scan with the scrotum in the center and with visu patients. Those with a scrotal mass who com alization of both iliac arteries laterally is reproducibly plained primarily of acute pain are included in obtained by placing the junction of penis and scrotum Group 1. at the center of the collimator (3) (Fig. 8). 4. Trauma (17 cases).All patientswith direct The use of micropore tape to pull the hemiscrotum to trauma to the scrotum are considered in this the ipsilateral thigh may be required to center the me group. Some had only pain, others had mild or dian raphe (Fig. 8, upper right). We do not use lead moderate scrotal swelling. shielding between the scrotum and thighs in the flow

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Volume 24, Number 8 739 CHEN, HOLDER,AND MELLOUL

FIG.8. Technique.(Upperleft)Collimatoriscenteredonjunctionofpenisandscrotum(arrow).(Upperright)Microporetape(straight arrow) Is often needed to center medianraphe (curvedarrow).(Lowerleft)Leadshielding(arrow)between scrotum and thighseliminates thigh “shine-through.―(Lower right) Imagesobtained with patient standingproduce shift of fluid. Camera provides some support. study because it obscures the vessels and often distorts bolus, we acquire six to eight sequential 5-sec frames, the relationships. In adults, 15—20mCi pertechnetate beginning with the first appearance of tracer on the (Tc-99m) is injected as a bolus into a vein in the an persistence oscilloscope, or at 10 sec after injection, tecubital fossa. The minimum dose used in children is whichever comes first (Fig. 3, upper). The “scrotalscan― 5 mCi. is obtained immediately after the RNA images are Since the interpretation of the RNA is concentrated completed (Fig. 3, lower left). A 700-K count image is on the first few frames during and after passage of the acquired with the multiformatter intensity setting of

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Volume 24, Number 8 741 CHEN. HOLDER,AND MELLOUL

999H for a single image (8 by 10 in.). The triple-lens ticular radionuclide angiography and static imaging: Anat Polaroid intensity setting is 510, which is the intensity omy, scintigraphic interpretation, and clinical indications. used for a 300-K count static brain image. A second Radio!ogy 125:739-752, 1977 3. HOLDER LE, MELLOUL M, CHEN DC: Current status of 700-K count image, with lead shielding between the radionuclide scrotal imaging. Semin Nuc! Med I I :232-249, scrotum and thighs, is obtained in all patients (Fig. 8, I 981 lower left). Great attention is paid to re-establish ana 4. TANAKAT, MISHKINFS,DATTANS:NuclearMedicine tomic symmetry after the lead has been positioned. Annual. In Radionuc!ide Imaging ofihe Scrotal Contents. Sometimes we obtain a third image with the patient FreemanLM, Weismann HS, Eds.New York, RavenPress, 1981,pp 195—221 standing, to produce confiratory shifts of fluid collections 5. LAWRENCE D, MISHKIN F: Radionuclide imaging in epi in the scrotum (Fig. 8, lower right). Occasionally, a didymoorchitis. J Urol I 12:387—389,1974 markerimage(usinga cobalt-57gelstring)ishelpfulin 6. RILEYTW, MOSBAUGHPG.COLESJL, etal: Useof ra defining the hemiscrotum, the location of the testicle, or dioisotope scan in evaluation of intrascrotal lesions.J Uro! the extent of a clinically palpable scrotal mass (Fig. 9, I 16:472—475,1976 7. SMITHSP, KING LR: Torsionof the testis:Techniquesof left, right). assessment.Urol C/in North Am 6:429-443, I 979 Interpretation.Ouranalysisof thescrotalRNA and 8. HOLDER LE, MARTIRE JR. SCHIRMER HKA: Clinical scan follows the flow chart shown in Fig. 10. The prin applicationsof testicular radionuclideangiographyand scrotal ciple of this approach was recently discussed (3). In the scanning.JAMA 245:2526-2529, 1981 RNA, we emphasize the importance of perfusion 9. STAGEKH,SCHOENVOGELR,LEWISS:Testicularscan ning: Clinical experiencewith 72 patients. J Urol 125:334— through the spermatic cord and extra-cord vessels, and 337,1981 also comment on scrotal perfusion as a separate entity. /0. DUNN EK, MACCHIA Ri, SOLOMON NA; Scintigraphic The exact source of increased perfusion to the scrotum pattern in missedtesticular torsion. Radiology I 39:175—180, can be uncertain. For example, in missed torsion there I981 may not be enough increased perfusion through the ii. LICH R, HOWERTONLW, AMIN M: Campbell's Urology, 4th ed. In Anatomy and Surgical Approach to the Uro extra-cord vessels to define them, but there is activity in Genital Tract in the Male. Harrison JH, Grittes RF, Perl the dartos during the arterial phase of the RNA. Simi mutter AD, et al. Eds.Philadelphia, WB Saunders, 1978,pp larly, in focal epididymitis there may not be enough 3—31 blood passing through the testicular and deferential ar 12. NETTER, FH: The Reproductive System. In The Ciba Col teries to outline them, but there will be a focal area of lection ofMedica/ Illustrations, Vol 2. Rochester,New York, CIBA, 1974,pp 64-86 increased epididymal perfusion seen in the early arterial /3. PARKERRM,R0BIs0NJR:Anatomyanddiagnosisoftor phase. sion ofthe testicle. J Urol 106:243-247, 1971 In the scrotal scan (or tissue-phase image), we try to 14. WHITAKER RH: In BenignDisordersofthe Testicle. Blandy search systematically for normal structures and to de J, Ed. Urology. New York, Lippincott, 1976, pp 1179- scribe carefully the areas of abnormally increased, de I 202 15. BURTONJA: Atrophy following testicular torsion. Br J Surg creased, or absent vascularity. Areas of increased or 59:422-426, 1972 decreased activity are described as to appearance (linear, /6. KINGLM, SEKARANSK,SAUERD,etal: Untwistingin curvilinear, round, halo-like, or half-moon-like) and delayed treatment of torsion of the spermatic cord. J Urol location (lateral, medial, superior, inferior; or more 112:217-221,1974 specifically, dartos, testicle, or epididymis). The normal 17. RINKER JR, ALLEN L: A lymphatic defect in hydrocele.Am Surg 17:681-686,1951 RNAs and scrotal scans have been described (2) (Fig. 18. KOHLER FP: On the etiology ofvaricocele. J Urol 97:741- 3). 742, 1967 Scrotal sonography.Scrotal sonographyhas been 19. BROWNJS, DUBIN L, HOTCHKISSRS: The varicocele as performed in 48 patients in this series. Details of the related to fertility. Fertil Steril I 8:46—56,1967 method and correlated results will be presented else 20. Row Ml, COPELSONLW, CLATWORTHYHW: The patent processusvaginalis and the inguinal hernia. J Ped Surg 4: where. Most of these patients had presented with scrotal 102-107,1969 masses, or with possible posttraumatic complications 21. LEAPE LL, HOLDEN TM: Pediatric surgery. In Davis such as hematocele, hydrocele, or intratesticular he (‘hristopherTextbook ofSurgery, I 2th cd. Sabiston DC, Ed. matoma. Philadelphia,WB Saunders,1981,pp 1351-1400 22. MCCORMACKJL, KRETZAW, TOCANTINSR:Traumatic rupture of the testicle. J Urol 96:80-82, 1966 23. GIKAS PW: Uropathology. In Fundamentals of Urology. REFERENCES Lapides J, Ed. Philadelphia, WB Saunders, 1976, pp 154- 161 I. NADEL NS, GITTER MH, HAHN LC, et al: Pre-operative 24. BUNCE PL: Scrotal Abnormalities. In Urologic Surgery. diagnosisof testicular torsion. Uro!ogy I :478—479,1973 Glenn iF, Ed. Hagerstown, Md, Harper & Row, 1975, pp 2. HOLDER LE, MARTIRE JR. HOLMES ER, III, et al: Tes 783-794

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