DOI:10.2214/AJR.07.2267
AJR 2007; 189:W331-W337
© American Roentgen Ray Society
MRI in the Histologic Characterization of Testicular Neoplasms
Athina C. Tsili1,
Constantine Tsampoulas1,
Xenofon Giannakopoulos2,
Dimitrios Stefanou3,
Yiannis Alamanos4,
Nikolaos Sofikitis2 and
Stavros C. Efremidis1
1 Department of Clinical Radiology, University Hospital of Ionnina, Leoforos S.
Niarchou, 45500, Platia Pargis, 2, 453 32, Ioannina, Greece.
2 Department of Urology, University Hospital of Ionnina, Leoforos S. Niarchou,
45500, Ioannina, Greece.
3 Department of Pathology, University Hospital of Ionnina, Leoforos S. Niarchou,
45500, Ioannina, Greece.
4 Department of Hygiene and Public Health, Panepistimioupolis, Leoforos S.
Niarchou, 45500, Ioannina, Greece.
Received March 17, 2007;
accepted after revision June 12, 2007.
WEB This is a Web exclusive article.
Address correspondence to A. C. Tsili
(a_tsili{at}yahoo.gr).
Abstract
OBJECTIVE. The purpose of our study was to investigate the potential
role of MRI in the preoperative characterization of the histologic type of
testicular tumors and, more specifically, to differentiate seminomatous from
nonseminomatous testicular neoplasms.
MATERIALS AND METHODS. Twenty-one patients with histologically
proven germ cell testicular tumors underwent MRI of the scrotum on a 1.5-T
unit. T2- and T1-weighted sequences before and after IV administration of
gadolinium chelate were performed. MRI studies were retrospectively reviewed
by two radiologists and findings were correlated with the histopathologic
diagnosis. An attempt was made to differentiate seminomatous from
nonseminomatous testicular tumors on the basis of signal intensity and
homogeneity of the lesions, presence of fibrovascular septa, tumor
encapsulation, and patterns of contrast enhancement. Interobserver agreement
was assessed using weighted kappa statistics.
RESULTS. MRI findings correctly characterized 19 (91%) of 21
testicular neoplasms (nine seminomatous and 10 nonseminomatous testicular
tumors), with excellent interobserver agreement. The presence of an
intratesticular lesion of predominantly low signal intensity on T2-weighted
images, with septa enhancing more than tumor tissue after contrast material
administration, was more suggestive for the diagnosis of a seminoma. Tumors
that were markedly heterogeneous both on unenhanced and contrast-enhanced
images were indicative of a nonseminomatous neoplasm.
CONCLUSION. Our study shows that MRI provides a credible
preoperative differentiation of seminomatous from nonseminomatous testicular
tumors, with excellent interobserver agreement.
Keywords: magnetic resonance • testicular tumors • testis
Introduction
Testicular cancer, although representing 1% of all malignancies in
men, is the most common neoplasm in boys and young adults from 15 to 34 years
old [1]. The estimated number
of new cases of testicular carcinoma in the United States during 2006 was
8,250, and cancer deaths due to this disease were estimated to occur in 370
patients [2]. Testicular cancer
most commonly presents as a painless scrotal mass.
Ninety-five percent of testicular carcinomas are germ cell tumors (GCTs)
arising from the germinal epithelium of the seminiferous tubules. The GCT line
is fairly evenly split between seminomas and nonseminomatous germ cell tumors
(NSGCTs). Seminomas, which account for 35-50% of all GCTs
[3,
4], are the most common type of
testicular carcinoma and are encountered mostly during the fourth decade of
life. NSGCTs typically occur earlier in life, usually during the third decade,
and include embryonal carcinoma, teratoma, choriocarcinoma, and yolk sac
tumor, although mixed tumors presenting with multiple histologic types are the
most common (40%) [3,
4]. Sonography is currently the
primary imaging technique in the assessment of scrotal disease
[3,
5]. However, because of its
wide field of view, multiplanar capabilities, and intrinsic high soft-tissue
contrast, MRI may represent an efficient supplemental technique for scrotal
imaging
[6-11].
Although the imaging features of testicular neoplasms reflect their gross
morphology and histologic characteristics
[4,
5,
12,
13], there are few reports in
the English-language literature correlating the MRI findings of testicular
neoplasms with their histologic characteristics
[12,
14].
The purpose of this study was to investigate the potential role of MRI in
the preoperative characterization of the histologic type of testicular tumors
and, more specifically, to differentiate seminomatous from nonseminomatous
testicular neoplasms.
Materials and Methods
We retrospectively reviewed the MRI examinations of 21 patients (age range,
22-47 years; mean age, 30 years) with histologically proven testicular GCTs
who were referred to the urology department because of a painless scrotal mass
between March 2002 and January 2006. These patients constitute our study
group. The institutional review board did not require approval or the
patients' informed consent for the review of medical records and MRI
examinations. All patients underwent sonography and MRI of the scrotum before
orchiectomy.
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Fig. 1A —43-year-old man with left testicular seminoma. Coronal T2-weighted
(A) and contrast-enhanced T1-weighted (B) images show
multinodular intratesticular mass lesion (arrows). Tumor is
homogeneous and of low signal intensity on T2-weighted image (A)
compared with normal testicular parenchyma. After gadolinium administration,
there is enhancement of tumor septa (B). Imaging features suggest
seminomatous lesion. Small right hydrocele (stars) is also seen.
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Fig. 1B —43-year-old man with left testicular seminoma. Coronal
T2-weighted (A) and contrast-enhanced T1-weighted (B) images
show multinodular intratesticular mass lesion (arrows). Tumor is
homogeneous and of low signal intensity on T2-weighted image (A)
compared with normal testicular parenchyma. After gadolinium administration,
there is enhancement of tumor septa (B). Imaging features suggest
seminomatous lesion. Small right hydrocele (stars) is also seen.
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Fig. 1C —43-year-old man with left testicular seminoma.
Photomicrograph of histologic section shows seminoma of classic type. Tumor
cells are uniform with abundant clear cytoplasm and are arranged in nests
outlined by fibrous bands. (H and E, x400)
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MRI Technique
MRI was performed on a 1.5-T unit (Gyroscan or Intera, Philips Medical
Systems) with the patient in the supine position. A 17-cm circular surface
coil was placed over the scrotum. Axial spin-echo T1-weighted imaging (TR/TE,
650/15; slice thickness, 3 mm; gap, 0.5 mm; field of view, 240 x 270 mm;
and matrix, 180 x 256 mm) was performed. This sequence with the addition
of frequency-selective fat suppression was repeated whenever the supervising
radiologist noted a lesion with high T1 signal intensity. No change of this
high signal intensity on the fat-suppressed sequence was attributed to the
presence of subacute hemorrhage, whereas a signal loss was considered
diagnostic for the presence of fat. Axial, coronal, and sagittal fast
spin-echo T2-weighted images (4,000/100; slice thickness, 3 mm; gap, 0.5 mm;
field of view, 240 x 270 mm; and matrix, 180 x 256 mm) were also
obtained. Unenhanced axial turbo spin-echo T1-weighted images (525/15; slice
thickness, 8 mm; gap, 0.8 mm; field of view, 240 x 270 mm; matrix, 256
x 256 mm) using the body coil covering the area from the aortic
bifurcation to the renal hila were obtained to assess for the presence of
retroperitoneal lymphadenopathy. Gadopentetate dimeglumine (Omniscan, GE
Healthcare) was administered IV in all cases (0.2 mmol/kg) and spin-echo
T1-weighted images covering the scrotal area in the axial, coronal, and
sagittal planes using the same parameters as the unenhanced images were
obtained.
MR Image Interpretation
MR image interpretation was performed by two radiologists with 4 and 2
years of experience in MRI of the scrotum. These radiologists did not have
knowledge of the histopathologic findings. MR image interpretation included
tumor detection and lesion characterization. Signal intensity of the lesions
was compared with that of normal testicular parenchyma. The homogeneity or
heterogeneity of the lesion signal was estimated, and the presence of tumor
capsule was sought. Areas of hyperintensity on T2-weighted images not
enhancing after gadolinium administration were considered as areas of
necrosis. The presence of hemorrhage or fat within the tumors was also
recorded. Bandlike structures of low signal intensity on T2-weighted images
enhancing after gadolinium administration were recognized as fibrovascular
septa. Finally, patterns of contrast enhancement were recorded.
On the basis of these findings, we made a step forward to differentiate
seminomas from nonseminomatous testicular tumors. Seminomas, because of their
cellular uniformity and nodular histologic characteristics (Fig.
1A,
1B,
1C), were expected to exhibit
signal homogeneity of low intensity on T2-weighted images. The presence of
septa within the tumor was also considered to characterize seminomatous
lesions. These septa were expected to enhance more than tumor tissue after
gadolinium administration. NSGCTs were expected to have heterogeneous signal,
with areas of hemorrhage or necrosis adding to their heterogeneity, especially
after gadolinium administration, probably because of their extremely
heterogeneous histologic appearance (Fig.
2A,
2B,
2C,
2D). The coexistence of fat
within these lesions was also considered compatible with the diagnosis of a
nonseminomatous lesion (Fig.
3A,
3B,
3C,
3D).
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Fig. 2A —26-year-old man with teratocarcinoma of right testicle.
Transverse (A) and sagittal (B) T2-weighted images depict left
testicular mass (arrow, A; long arrow, B) with
markedly heterogeneous signal. Tumor is surrounded by low-signal-intensity
halo (long arrow, B), corresponding histologically to a
fibrous capsule. There is invasion of the tunica albuginea by the tumor
(short arrow, A).
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Fig. 2B —26-year-old man with teratocarcinoma of right testicle.
Transverse (A) and sagittal (B) T2-weighted images depict left
testicular mass (arrow, A; long arrow, B) with
markedly heterogeneous signal. Tumor is surrounded by low-signal-intensity
halo (long arrow, B), corresponding histologically to a
fibrous capsule. There is invasion of the tunica albuginea by the tumor
(short arrow, A).
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Fig. 2C —26-year-old man with teratocarcinoma of right testicle.
Sagittal contrast-enhanced T1-weighted image shows heterogeneous enhancement
of tumor. Areas of hyperintensity within lesion on T2-weighted images that did
not enhance after gadolinium administration (arrows) proved
histologically to represent areas of necrosis. Imaging features in this case
suggest nonseminomatous lesion.
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Fig. 2D —26-year-old man with teratocarcinoma of right testicle.
Photomicrograph of histologic section shows heterogeneous tumor containing
squamous epithelium, cartilage, and embryonic body (center of
photo—mixed teratoma and embryonal carcinoma). (H and E, x100)
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Fig. 3B —29-year-old man with mature cystic teratoma of left testicle.
Transverse T1-weighted (B) and fat-suppressed T1-weighted (C)
images show areas (arrows) of high signal intensity and loss of
signal on fat-suppressed images, compatible with presence of fat.
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Fig. 3C —29-year-old man with mature cystic teratoma of left testicle.
Transverse T1-weighted (B) and fat-suppressed T1-weighted (C)
images show areas (arrows) of high signal intensity and loss of
signal on fat-suppressed images, compatible with presence of fat.
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The interobserver agreement on MR interpretation between the two
radiologists was quantified by using weighted kappa statistics. Evaluation of
MRI findings was retrospectively correlated with the histopathologic findings,
which were the standard of reference. The histologic sections of each case
were reviewed in retrospect by one pathologist with 25 years of experience in
scrotal pathology, and the histologic findings were correlated with the MR
diagnosis.
Results
Histologic examination of the surgical specimens disclosed the presence of
21 testicular neoplasms. Eleven were found to be nonseminomatous testicular
tumors, including mixed NSGCTs: teratocarcinoma (n =4); embryonal
carcinoma and seminoma (n =1); teratoma, embryonal carcinoma, and
yolk sac tumor (n = 1); teratoma, embryonal carcinoma,
choriocarcinoma, and yolk sac tumor (n = 1); embryonal carcinoma
(n = 1); mature cystic teratoma (n = 2); and yolk sac tumor
(n = 1). Ten neoplasms proved histologically to represent
seminomas.
MRI findings led to a correct histologic diagnosis in 19 (91%) of 21 cases.
MRI enabled the correct preoperative characterization of nine of 10 seminomas.
Three seminomas were recognized as multinodular, sharply defined, homogeneous
tumors of low signal intensity on T2-weighted images (Fig.
1A,
1B,
1C). The other six cases were
predominantly of low intensity on T2-weighted images but exhibited signal
heterogeneity with small areas of hemorrhage (Fig.
4A,
4B,
4C) in four cases and areas of
necrosis in two cases. In all cases of seminomas, fibrovascular septa were
detected within the tumors, showing greater enhancement than tumor tissue
after gadolinium administration (Fig.
5A,
5B,
5C,
5D).
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Fig. 4A —28-year-old man with seminoma of left testicle. Coronal
T2-weighted (A) and contrast-enhanced T1-weighted (B) images
depict large left testicular mass. Tumor is heterogeneous but mainly of low
signal intensity on T2-weighted image (A). There are multiple septa
(arrows, B) within the lesion, detected both on T2-weighted
and contrast-enhanced T1-weighted images, suggesting diagnosis of seminoma.
There is interruption of tunica albuginea by tumor (arrow, A),
suggestive of invasion, which was proven histologically. Star indicates right
testicle.
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Fig. 4B —28-year-old man with seminoma of left testicle. Coronal
T2-weighted (A) and contrast-enhanced T1-weighted (B) images
depict large left testicular mass. Tumor is heterogeneous but mainly of low
signal intensity on T2-weighted image (A). There are multiple septa
(arrows, B) within the lesion, detected both on T2-weighted
and contrast-enhanced T1-weighted images, suggesting diagnosis of seminoma.
There is interruption of tunica albuginea by tumor (arrow, A),
suggestive of invasion, which was proven histologically. Star indicates right
testicle.
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Fig. 4C —28-year-old man with seminoma of left testicle. Transverse
T1-weighted image depicts small hyperintense focus (arrow) within
mass, corresponding to area of hemorrhage. Star indicates right testicle.
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Fig. 5A —47-year-old man with left testicle seminoma invading
ipsilateral spermatic cord. Sagittal T2-weighted (A), coronal
T2-weighted (B), and contrast-enhanced T1-weighted (C) images
depict large tumor involving left testicle and invading epididymis and
spermatic cord. Tumor is inhomogeneous but mainly hypointense on T2-weighted
images. There are bandlike structures (arrows) within mass that are
of low signal intensity on T2-weighted images. These structures enhance more
than rest of tumor after gadolinium administration, indicating fibrovascular
septa.
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Fig. 5B —47-year-old man with left testicle seminoma invading
ipsilateral spermatic cord. Sagittal T2-weighted (A), coronal
T2-weighted (B), and contrast-enhanced T1-weighted (C) images
depict large tumor involving left testicle and invading epididymis and
spermatic cord. Tumor is inhomogeneous but mainly hypointense on T2-weighted
images. There are bandlike structures (arrows) within mass that are
of low signal intensity on T2-weighted images. These structures enhance more
than rest of tumor after gadolinium administration, indicating fibrovascular
septa.
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Fig. 5C —47-year-old man with left testicle seminoma invading
ipsilateral spermatic cord. Sagittal T2-weighted (A), coronal
T2-weighted (B), and contrast-enhanced T1-weighted (C) images
depict large tumor involving left testicle and invading epididymis and
spermatic cord. Tumor is inhomogeneous but mainly hypointense on T2-weighted
images. There are bandlike structures (arrows) within mass that are
of low signal intensity on T2-weighted images. These structures enhance more
than rest of tumor after gadolinium administration, indicating fibrovascular
septa.
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Fig. 5D —47-year-old man with left testicle seminoma invading
ipsilateral spermatic cord. Photomicrograph of histologic section shows
testicular seminoma. Neoplastic cells infiltrate spermatic cord. (H and E,
x100)
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The number of septa was variable, ranging from less than five to numerous,
the latter detected in cases of large neoplasms (Figs.
4A,
4B,
4C and
5A,
5B,
5C,
5D). Septal thickness was also
variable. In five seminomas, septa were thin, with thickness less than 3 mm,
and in the other four cases, thick septa with thickness greater than 3 mm were
found to coexist. Despite signal heterogeneity and presence of hemorrhage and
necrosis in the six seminomatous lesions, these tumors were correctly
characterized because of the presence of distinctive MRI features such as
predominantly low signal intensity on T2-weighted images and the presence and
enhancement of tumor septa.
Ten testicular lesions were correctly characterized on MRI as
nonseminomatous tumors. These lesions appeared as heterogeneous masses on
T2-weighted images and showed heterogeneous enhancement after gadolinium
administration (Fig. 2A,
2B,
2C,
2D). Areas of necrosis were
detected in six cases and areas of hemorrhage in seven. Included in the
category of nonseminomatous tumors were two lesions detected with areas of
high signal intensity and loss of signal on T1- and fat-suppressed T1-weighted
images (Fig. 3A,
3B,
3C,
3D), respectively, a finding
diagnostic for the presence of fat. The presence of enhancement in the last
two cases made it possible to diagnose these tumors as mature cystic
teratomas—proven histologically—allowing us to differentiate them
from an epidermoid cyst, which should always be considered in the presence of
a fatcontaining mass within the testicles
[15-17].
Nine of 10 nonseminomatous tumors and five of nine seminomas were surrounded
by a low-signal-intensity halo. This halo proved histologically to represent a
fibrous capsule.
MRI was incorrect in the preoperative diagnosis in one case of an embryonal
carcinoma and another case of an anaplastic seminoma. In the first case, a
testicular tumor was detected on T2-weighted images as relatively homogeneous
and of low signal intensity. Therefore, it was characterized as a seminoma
(Fig. 6), whereas in the
second case, the lesion was markedly inhomogeneous on T2-weighted images,
presenting large areas of necrosis and enhancing heterogeneously, therefore
resembling closely a nonseminomatous lesion (Fig.
7A,
7B). The MRI features in each
individual case for the seminomas and the nonseminomatous testicular tumors
are illustrated in Tables 1 and
2, respectively.
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Fig. 6 —23-year-old man with embryonal carcinoma of right testicle.
Transverse T2-weighted image shows small tumor (arrow) involving
right testicle. Lesion is relatively homogeneous and hypointense, suggesting
diagnosis of seminoma.
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Fig. 7A —28-year-old man with anaplastic seminoma of right testicle.
Coronal T2-weighted (A) and contrast-enhanced T1-weighted (B)
images show large inhomogeneous right testicular mass invading ipsilateral
epididymis (long arrow). Finding was confirmed on histology. Because
of mass heterogeneity, both on unenhanced and contrast-enhanced MR images, it
was incorrectly characterized as nonseminomatous lesion. There is also small
right hydrocele (short arrow, A). Star indicates left
testicle.
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Fig. 7B —28-year-old man with anaplastic seminoma of right testicle.
Coronal T2-weighted (A) and contrast-enhanced T1-weighted (B)
images show large inhomogeneous right testicular mass invading ipsilateral
epididymis (long arrow). Finding was confirmed on histology. Because
of mass heterogeneity, both on unenhanced and contrast-enhanced MR images, it
was incorrectly characterized as nonseminomatous lesion. There is also small
right hydrocele (short arrow, A). Star indicates left
testicle.
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The interobserver agreement between the readings of the two radiologists
was excellent (
= 1.0).
Discussion
The distinction of GCTs in seminomatous and nonseminomatous neoplasms is
important for determining treatment and prognosis. Seminomas have the best
prognosis among GCTs because of their high sensitivity to radiation and
chemotherapy. Nonseminomatous histologic features are associated with poor
prognosis because they are not as radio-sensitive as seminomas.
Classic seminomas histologically are usually homogeneously solid, lobulated
masses that may contain sharply circumscribed areas of necrosis.
Microscopically, tumor cells are uniform with abundant clear cytoplasm
characteristically arranged in nests outlined by fibrous bands; in 80% of
cases, these bands are infiltrated by lymphocytes and plasma cells, possibly
due to a host reaction to the tumor. The imaging features of seminomas reflect
their histologic characteristics and their uniform cellular nature.
On MRI, seminomas usually appear as multinodular tumors of uniform signal
intensity that are hypointense on T2-weighted images. Bandlike structures of
low signal intensity on T2-weighted images may be detected within these
tumors, corresponding to the fibrovascular septa. In our study, these septa
showed greater enhancement than tumor tissue after gadolinium administration.
These imaging features enabled a correct preoperative characterization for
nine of 10 seminomas in this study, even in the cases where areas of necrosis
or hemorrhage were found to coexist within the tumors. Imaging findings
described for dysgerminoma, the ovarian counterpart of seminoma, are similar
[13,
18-20].
These tumors are usually multilobulated, uniformly homogeneous, and have
prominent septa, which enhance after IV contrast material administration
[13,
18-20].
NSGCTs include a large group of histologically diverse neoplasms. Four
basic types have been recognized: embryonal carcinoma, teratoma,
choriocarcinoma, and yolk sac tumor. The combination of two or more types of
these neoplasms results in mixed GCTs. Some more common patterns are teratoma
and embryonal carcinoma; seminoma and embryonal carcinoma; and teratoma,
embryonal carcinoma, and yolk sac tumor.
Embryonal carcinoma has grossly a more variable appearance than seminoma
[3]. It is mainly a solid tumor
containing foci of hemorrhage and necrosis. Microscopically, it is composed of
undifferentiated cells or may show signs of early differentiation toward
embryonic structures, trophoblast, or extraembryonic endoderm or mesoderm in
the form of papillary or glandular formations. The tumor has a carcinomatous
appearance; the cells are more anaplastic, with prominent variation in size
and shape.
Teratoma, on the other hand, macroscopically, is predominantly cystic and
multiloculated [3]. Foci of
cartilage are usually present within the tumor. All types of tissues can be
seen microscopically, most commonly nerve, cartilage, and various types of
epithelium. These tumors are further divided into mature and immature
teratomas and those with malignant areas. Dermoids, representing the most
common teratomatous lesion in the ovary, constitute only a small minority of
testicular teratomas [3,
4].
Choriocarcinomas represent the most lethal form of testicular carcinomas.
These tumors are often small, usually hemorrhagic, and partially necrotic
[3]. Yolk sac tumor has a soft
consistency and a microcystic appearance
[3]. Therefore, nonseminomatous
testicular tumors are expected to appear as heterogeneous masses on MRI, with
areas of hemorrhage or necrosis showing heterogeneous enhancement after
gadolinium administration. Our differential diagnosis was based on criteria,
such as those described previously, and it was successful in 10 of 11
nonseminomatous testicular tumors. Tumor heterogeneity and heterogeneous
enhancement proved the most valuable findings in the characterization of a
nonseminomatous lesion.
Schultz-Lampel et al. [14]
succeeded in making a correct preoperative differentiation between seminomas
and nonseminomatous tumors in 42 (62%) of 67 patients with testicular
carcinomas in their study, although the exact criteria used for this
differentiation are not described. Johnson et al.
[12] in a study of 15 patients
with GCTs showed that MRI could be used to provide a preoperative histologic
classification of these tumors. By using T1- and T2-weighted sequences, the
authors correctly characterized 13 (87%) of 15 neoplasms. The presence of a
relatively homogeneous testicular mass of low signal intensity on T2-weighted
images was considered indicative of a seminomatous lesion. On the other hand,
a markedly heterogeneous mass with areas of necrosis or hemorrhage was
characterized as a nonseminomatous lesion. It is suggested from our study that
the presence of fibrovascular septa, seen on T1- or contrast-enhanced
T2-weighted images, is indicative of a seminomatous lesion.
Our MR protocol also included the administration of gadolinium chelate
compounds and study of the patterns of enhancement of germ cell testicular
neoplasms. In cases of seminomas, fibrovascular septa were found to enhance
more than tumor tissue. On the other hand, nonseminomatous testicular tumors
showed a markedly heterogeneous enhancement. Areas that did not enhance were
found histologically to represent areas of necrosis or hemorrhage. Using the
above criteria, this study enabled the differentiation between seminomatous
from nonseminomatous testicular tumors in 19 (91%) of 21 cases. The presence
of a tumor capsule, seen on both seminomas and nonseminomatous tumors, could
not be used in the preoperative differentiation of these tumors.
Imaging has an important role in the investigation of scrotal masses,
although physical examination represents the primary technique for the
evaluation of scrotal abnormalities. Sonography is the standard imaging
technique for the investigation of testicular lesions
[5,
21-25].
It is easily performed, inexpensive, and has been shown to be 100% sensitive
in the identification of scrotal masses. MRI of the scrotum has been used as
an alternative technique for the diagnosis of scrotal disease
[6-11,
26-28].
It is a diagnostic tool of high performance for morphologic assessment and
tissue characterization in the preoperative evaluation of scrotal masses.
MRI can reduce the incidence of diagnostic surgical explorations for
scrotal pathology. The technique has been proven highly accurate in the
differentiation of extratesticular from intratesticular disease
[10,
29-31],
providing good results in the distinction between benign and malignant
testicular masses [4,
32-34]
and allowing the accurate evaluation of the local extent of the disease in
cases of testicular carcinoma
[10]. MRI is particularly
recommended when sonographic findings are inconclusive or inconsistent with
the clinical findings [34,
35]. Moreover, this study
showed that MRI findings could be closely correlated with the histologic
characteristics of testicular neoplasms, providing a preoperative
classification of the histologic type of testicular tumors.
A potential criticism of our study is that although all patients underwent
sonography and MRI of the scrotum, no direct comparison between the results of
both techniques was performed. This was also a retrospective study of the MRI
characteristics of a small number of testicular tumors (n = 21) in an
attempt to pre-operatively differentiate seminomatous from nonseminomatous
testicular neoplasms, and perhaps there was some bias because most
radiologists are familiar with the imaging features of these neoplasms
[4,
5,
13]. The more important
question is whether MRI offers the ability to differentiate testicular
malignancies from benign intrascrotal lesions (such as focal testicular
infarction, epidermoid cyst, or granulomatous orchitis), obviating an unwanted
orchiectomy. This should be a point of a future research. Finally, a
limitation of our MR protocol was that it did not include dynamic
contrast-enhanced imaging to assess potential differences in enhancement
patterns between seminomas and nonseminomatous testicular tumors.
In conclusion, our study showed that MRI is able to provide a credible
preoperative differentiation of seminomatous from nonseminomatous testicular
tumors, with excellent interobserver agreement. The presence of an
intratesticular lesion of predominantly low signal intensity on T2-weighted
images with septa enhancing more than tumor tissue after contrast material
administration is more suggestive for the diagnosis of a seminomatous lesion.
Tumors that are heterogeneous both on unenhanced and contrast-enhanced images
are indicative of a nonseminomatous neoplasm.
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Abstract
Introduction
