Without and With Dynamic Gadolinium Enhancement

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1 MRI of Focal Splenic Lesions bdominal Imaging Pictorial Essay Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved C D E M N E U T R Y L I M C I G O F I N G ntonio Luna 1 Ramón Ribes 2 Pilar Caro 3 Luis Luna 1 Eugenia umente 4 Pablo R. Ros 5 Luna, Ribes R, Caro P, Luna L, umente E, Ros PR Keywords: CT, lymphoma, MRI, spleen DOI: /JR Received ugust 6, 2004; accepted after revision March 15, Department of Radiology, MR Unit, Clinica Las Nieves, Sercosa, Carmelo Torres 2, Jaén 23007, Spain. ddress correspondence to. Luna (aluna70@sercosa.com). 2 Department of Radiology, MR Unit, Reina Sofia Hospital, Córdoba 14004, Spain. 3 MR Unit, Dadisa, Recinto Inferior Zona Franca, Cádiz 11001, Spain. 4 MR Unit, Ressalta, Hospital San Juan de Dios, Córdoba 14012, Spain. 5 Department of Radiology, righam and Women s Hospital, Harvard Medical School, oston, M JR 2006; 186: X/06/ merican Roentgen Ray Society MRI of Focal Splenic Lesions Without and With Dynamic Gadolinium Enhancement OJECTIVE. Our purpose was to identify the MR features of focal splenic lesions with an emphasis on enhancement patterns. The addition of a contrast-enhanced dynamic sequence to unenhanced MR images improves the study of focal splenic lesions. The analysis of the MR features along with the clinical history permits either the characterization of the most common splenic lesions or improvement in the detection of malignant diseases. CONCLUSION. Dynamic contrast-enhanced MRI improves the detection and characterization of focal splenic lesions. tate-of-the-art MRI sequences, S including the use of dynamic contrast-enhanced series on immediate and delayed acquisitions, permit the characterization of the most common splenic lesions, such as cysts, small hemangiomas, and hamartomas; and improvement in the detection of malignant diseases such as lymphoma and metastases. Nevertheless, percutaneous or surgical biopsy is necessary when malignancy is suspected or focal lesions with atypical MRI features are present. ppendix 1 lists the classification of focal splenic lesions discussed in this article. Technique lthough unenhanced MRI detects most cysts and hemangiomas, it is usually not sensitive enough for the detection of less common splenic lesions. The use of a dynamic contrast-enhanced gradient-echo sequence improves the detection of focal splenic lesions, mainly in the acquisition obtained immediately after contrast administration, allowing a better differentiation between normal and abnormal spleen [1] because of differences in blood supply. Our standard protocol includes a turbo gradient-echo axial T1- weighted sequence; an axial and coronal breath-hold turbo spin-echo T2-weighted sequence; an axial STIR sequence; and a 3D fatsuppressed gadolinium-enhanced dynamic series with immediate (12 sec after contrast injection) and 1- and 5-min delayed contrastenhanced acquisitions. Normal Variants Notches, clefts, and accessory spleens (spleniculi) can be misinterpreted as splenic nodules. The identical signal intensity of these pseudolesions to splenic parenchyma in all sequences allow their characterization. MRI appearance of these nodules is similar to that of splenosis. Polysplenia Syndrome Polysplenia syndrome is a congenital disorder associating thoracoabdominal abnormalities and complete situs ambiguous (Fig. 1), which typically shows multiple splenic nodules. Infectious Lesions MRI surpasses enhanced CT in the evaluation of fungal infections [2]. Candida albicans, spergillus fumigatus, and Cryptococcus neoformans are responsible for the majority of these infections in immunocompromised patients. cute Candida abscesses appear on fat-suppressed turbo spinecho T2-weighted images (Fig. 2) as small hyperintense subcapsular lesions that do not usually show peripheral enhancement in the acute stage because of the immunocompromised state of these patients; or in the chronic stage because of fibrotic changes [3]. acterial abscesses, which are usually larger than fungal ones, are frequently associated with endocarditis and typically show peripheral and perilesional enhancement on contrast-enhanced sequences [4] (Fig. 3). Hydatid cysts are secondary to infection by JR:186, June

2 Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig. 1 3-month-old girl with polysplenia syndrome. fter chest radiography showed dextrocardia, MRI was performed to rule out associated malformations. and, xial unenhanced () and delayed contrast-enhanced () turbo gradient-echo T1-weighted sequences show mirror-image location of upper abdominal viscera and vessels. Right hypochondrium is occupied by multiple independent splenic nodules of different sizes that show homogeneous enhancement in delayed phase. Findings correspond to polysplenia syndrome associated with situs ambiguous. Fig year-old man with HIV infection and acute hepatosplenic candidiasis., xial fat-saturated turbo spin-echo T2-weighted image shows multiple round hyperintense lesions in liver and spleen (arrowheads) representing Candida albicans microabscesses., xial contrast-enhanced turbo spin-echo T1-weighted delayed phase image shows homogeneous enhancement of hepatic lesions and scarce enhancement of splenic lesions (arrowheads), with only one of them detectable. Fat-saturated turbo spin-echo T2-weighted images make lesions appear more conspicuous. Echinococcus granulosus that appear as single or multiple cysts with or without wall calcifications (Fig. 4). Healed granulomas are better depicted by CT than MRI because they are completely calcified. Cysts Cysts are the most common benign focal splenic masses [2]. They can be divided into epithelial or true cysts, which are lined with epithelium and may show septations and peripheral calcifications (Fig. 5); and false cysts or pseudocysts that can be posttraumatic or secondary to pancreatitis and usually have a more heterogeneous appearance than true cysts (Fig. 6) JR:186, June 2006

3 MRI of Focal Splenic Lesions Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved Vascular Lesions Focal Vascular Lesions enign tumors Hemangioma is the second most common focal lesion and the most common benign tumor of the spleen [5]. Most hemangiomas are smaller than 2 cm [4], well-defined, homogeneous, hypo- to isointense on T1-weighted images, and most commonly hyperintense on T2-weighted images compared with splenic parenchyma (Fig. 6). On dynamic contrast-enhanced Fig year-old man with Staphylococcus aureus abscess secondary to endocarditis. and, xial gradient-echo unenhanced () and immediate postcontrast () 2D fat-suppressed T1-weighted images show peripheral enhancement of huge cysticappearing lesion. Clinical data and peripheral enhancement on enhanced MRI sequences led to diagnosis of splenic abscess. studies, they usually show peripheral enhancement with centripetal, delayed progression [5] (Fig. 7), although the typical nodular, peripheral enhancement of hepatic hemangiomas is uncommon [2, 5]. Smaller hemangiomas may also show homogeneous enhancement on immediate postcontrast acquisitions (Fig. 8), remaining enhanced on delayed images [2]. Therefore, any small splenic lesion that is hyperintense on T2- weighted images and shows homogeneous or peripheral enhancement on immediate postcontrast images should be considered a hemangioma. Larger hemangiomas are heterogeneous with areas of hemorrhage and thrombosis and enhance in a centripetal fashion with persistent nonenhancing areas [5] (Fig. 9). Therefore, larger hemangiomas need follow-up or biopsy to rule out angiosarcoma. Littoral cell angioma and hemangioendothelioma are rare, benign, vascular tumors that can show siderotic nodules [5]. Fig year-old woman with splenic hydatid cyst., Septated hyperintense splenic mass is seen on coronal turbo spin-echo T2-weighted image. Smaller peripheral cyst represents daughter cyst (arrow). (Fig. 4 continues on next page) JR:186, June

4 Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig. 4 (continued) 46-year-old woman with splenic hydatid cyst. and C, xial gradient-echo unenhanced () and delayed contrast-enhanced (C) 3D T1-weighted images show cystic nature of mass. These are typical features of hydatid cysts, although similar appearances can be found in epithelial cysts or lymphangiomas. Diagnosis of hydatid cyst was established after splenectomy. C Fig year-old woman with splenic epithelial cyst. Huge cystic mass was discovered in left upper quadrant on sonography. MRI was performed to determine its organ of origin. and, xial unenhanced () and delayed contrast-enhanced () turbo gradient-echo T1-weighted images show huge homogeneous nonenhancing mass intimately related to spleen, which is shifted laterally. Mass corresponds to splenic epithelial cyst as confirmed after splenectomy JR:186, June 2006

5 MRI of Focal Splenic Lesions Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved Malignant neoplasms ngiosarcoma typically appears as multiple nodular heterogeneous masses, including siderotic nodules, with intense and heterogeneous enhancement [5]. In the uncommon case of whole spleen replacement, an increased risk for splenic rupture exists. Hemangiopericytoma rarely involves the spleen. Nonneoplastic lesions On MRI, splenic infarcts are more conspicuous on delayed contrast-enhanced images as defined perfusion defects [2]. typical feature is the rim sign or capsular enhancement caused by blood supply from capsular vessels [6]. Intrasplenic hematomas in the acute phase show high signal intensity on T1-weighted images [6]. Later, they Fig year-old man with pancreatic pseudocyst with splenic involvement. Patient had history of acute pancreatitis episodes. Huge complicated cyst was discovered during routine sonography study in upper abdomen. MRI was performed for further characterization of lesion. and, Sagittal unenhanced () and delayed contrast-enhanced () turbo field-echo T1-weighted images reveal bilobulated cystic mass surrounding and extending to spleen (asterisk). Note presence of fluid fluid level (arrows) within superior component of mass with hyperintense signal on T1-weighted sequence of dependent component, indicating hemorrhagic content. usually present as a cystic mass. Old, healed hematomas are commonly hypointense on T1- and T2-weighted images (Fig. 10). Diffuse Vascular Lesions Hemangiomatosis is a rare vascular tumorlike entity that has a similar appearance to angiosarcoma (Fig. 11). On MRI, lymphangioma usually presents as a multicystic lesion, although some of the cysts may be hyperintense on T1-weighted images (Fig. 12) because of their proteinaceous or hemorrhagic content [5]. lthough malignant degeneration of lymphangioma is rare, MRI is able to show intracystic solid components [5]. Peliosis usually presents in immunocompromised patients [5], and its most common MRI appearance is that of multiple cystic and hemorrhagic nodules, sometimes of hypervascular nature, associated with siderotic nodules (Fig. 13). Nonvascular Tumors enign Hamartoma is a rare nonneoplastic tumor that usually appears as a sharply defined, rounded, single solid lesion [2]. Its heterogeneous hyperintensity on T2-weighted images (Fig. 14) and its typical faint heterogeneous JR:186, June

6 Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved C Fig. 7 8-year-old boy with multiple small cavernous hemangiomas showing centripetal enhancement pattern., Coronal fat-saturated turbo spin-echo T2-weighted image shows multiple hyperintense splenic nodules. D, Immediate (), 1 min (C), and delayed (D) postcontrast gradient-echo T1-weighted images show progressive centripetal enhancement typical of hemangiomas. Note progressive peripheral enhancement on immediate- and 1-min postcontrast images and how nodules become almost completely isointense to splenic parenchyma on delayed acquisition. D enhancement on immediate postcontrast-enhanced images are key features in the differentiation between hamartomas and hemangiomas [7]. On delayed postcontrast images, hamartoma enhances in a relatively uniform and intense fashion (Fig. 14C) with central hypovascular areas [7]. Therefore, MRI is the preferable imaging technique for its distinction from hemangiomas JR:186, June 2006

7 MRI of Focal Splenic Lesions Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old man with splenic capillary hemangioma showing homogeneous enhancement pattern. and, xial unenhanced () and immediate postcontrast () volumetric 3D gradient-echo T1-weighted images reveal homogeneous enhancement typical of splenic capillary hemangiomas. On delayed acquisition (not shown), although lesion showed some washout, it remained more enhanced than splenic parenchyma. Fig. 9 8-year-old boy with systemic angiomatosis and cavernous hemangioma with central scar. and, Unenhanced () and delayed contrast-enhanced () fat-saturated turbo spin-echo T1-weighted images show hypointense nodule that shows peripheral and heterogeneous internal enhancement after IV contrast administration, related to presence of central scar, in cavernous hemangioma. iopsy was not necessary as this patient had multiple hemangiomas in spleen, liver, and neck (not shown). Malignant Lymphoma is the most common splenic malignancy [4] and can present as multiple focal lesions or diffuse involvement or, more rarely, as a single mass (Fig. 15). oth Hodgkin s and non-hodgkin s lymphoma may present in the spleen as the primary site or as a part of systemic involvement. Immediate postcontrast MRI images surpass CT in their evaluation [2], although the role of MDCT is not established yet. Lymphomatous nodules tend to be isointense to splenic parenchyma on T1- and T2-weighted images (Fig. 12), although they can be hypointense on T2-weighted images [2, 6]. This feature is useful in their distinction from metastases, which are rarely hypointense on T2- weighted images [2]. Immediate postcontrast images show hypovascular nodules, which usually become isointense to the spleen within the first minute after contrast administration [4] (Fig. 16). Chloromas, most commonly associated with chronic lymphocytic leukemia, are rare. They appear as multiple ill-defined masses without enhancement on immediate postcontrast images [2] (Fig. 17). Metastases are commonly isointense to the spleen on unenhanced sequences [6], although they can be hyperintense on T2- weighted images, mainly when necrosis or cystic changes are present (Fig. 18). Hemorrhagic or melanoma metastases can show JR:186, June

8 Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved C Fig year-old man with splenic hematoma., xial T2-weighted image shows round hypointense mass in anterior portion of spleen, representing old, healed hematoma. and C, xial unenhanced () and delayed contrast-enhanced (C) gradient-echo T1-weighted images show hypointense mass on T1-weighted image with peripheral and heterogeneous internal enhancement. ppearance of lesion on MRI was diagnostic and did not change in several follow-up MRI studies. Fig year-old woman with diffuse splenic hemangiomatosis., Coronal turbo spin-echo T2-weighted image shows multiple hyperintense focal splenic lesions (arrowheads) and hypointense nodule representing siderotic nodule (arrow) in enlarged spleen. (Fig. 11 continues on next page) 1540 JR:186, June 2006

9 MRI of Focal Splenic Lesions Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig. 11 (continued) 41-year-old woman with diffuse splenic hemangiomatosis., xial unenhanced gradient-echo T1-weighted image shows hypovascular nodules with areas of magnetic susceptibility artifact (arrows) representing siderotic nodules. C, Postcontrast (1 min) gradient-echo T1-weighted image reveals subtle peripheral enhancement of both nodules (arrows). Superior nodule also presents heterogeneous internal enhancement. Heterogeneous splenic appearance is also possible in cases of angiosarcoma or littoral cell angioma. Fig year-old woman with splenic lymphangioma. Complex cystic mass was detected in previous routine sonography study and confirmed later on enhanced CT. and, xial unenhanced () and contrast-enhanced () gradient-echo T1-weighted images show subcapsular multilocular mass with hypo- (arrowheads) and hyperintense (arrow) nonenhancing areas, revealing their cystic nature. Hyperintense areas were secondary to proteinaceous content. Diagnosis was confirmed after splenectomy. Ghosting artifact was result of poor breath-holding. C high signal on T1-weighted images [2]. These last two features can be used to distinguish metastases from lymphoma, as lymphoma rarely shows necrosis or hemorrhage. Metastases are typically hypovascular on immediate postcontrast images, becoming isointense after the first postcontrast minute [2] (Figs D). Miscellaneous In cases of lysosomal storage disorders, such as Gaucher s and Niemann-Pick diseases, MRI may detect splenic nodules and JR:186, June

10 Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old woman with disseminated tuberculosis and hepatosplenic peliosis. and, xial T1 gradient-echo unenhanced () and immediate postcontrast () images show multicystic mass on spleen (arrows, ) with septal and peripheral enhancement and several liver lesions with peripheral enhancement or multicystic appearance (arrowheads, ). Liver lesions were not detectable on unenhanced image. Fig year-old boy with splenic hamartoma., Coronal fat-saturated turbo spin-echo T2-weighted image reveals heterogeneous hyperintense mass in inferior pole of spleen. and C, Unenhanced () and delayed contrast-enhanced (C) turbo spin-echo T1- weighted images show intense mildly heterogeneous enhancement within mass, which was hypointense on precontrast image. This is typical presentation of hamartoma. Larger hemangiomas may have similar appearance, and biopsy may be necessary for differentiation. lthough splenectomy was performed in this case, follow-up imaging may be acceptable strategy to assess benign origin of hamartomas. C 1542 JR:186, June 2006

11 MRI of Focal Splenic Lesions Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved infarcts [8] (Fig. 19). Splenic sarcoidosis appears as multiple tiny, hypovascular and hypointense nodules on all sequences [2]. Gamna-Gandy nodules or siderotic nodules C Fig year-old woman with left flank pain and primary splenic nodular non-hodgkin s lymphoma. Splenic mass was detected in previous sonography study, and MRI study was performed for its characterization., xial STIR image reveals irregular heterogeneous hypointense mass with extension beyond splenic margins (white arrows). and C, xial unenhanced () and immediate postcontrast (C) gradient-echo T1-weighted images show hypovascular mass on immediate image that becomes isointense to spleen on delayed acquisition (not shown). Notice presence of small peripheral siderotic nodules (arrowhead). are foci of iron deposits that result from splenic microhemorrhages. These nodules are usually smaller than 1 cm and hypointense on all sequences (Fig. 19). T2*- weighted and gadolinium-enhanced T1- weighted images increase their conspicuity, rendering MRI superior to sonography and CT in their detection [6]. Fig year-old man with weight loss, weakness, and multinodular non- Hodgkin s lymphoma., T2-weighted image shows normal spleen with no evidence of focal lesions. (Fig. 16 continues on next page) JR:186, June

12 Fig. 16 (continued) 56-year-old man with weight loss, weakness, and multinodular non-hodgkin s lymphoma. D, xial unenhanced (), immediate postcontrast (C), and delayed postcontrast (D) gradient-echo T1-weighted images show multiple small hypovascular nodules on immediate acquisition that are not detectable on delayed acquisition. Splenectomy was performed and multinodular non-hodgkin s lymphoma was confirmed. Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved C D Conclusion Dynamic enhanced sequences improve the evaluation of focal splenic lesions, allowing the characterization of cysts, smaller hemangiomas, hamartomas, and acute fungal infections and increasing the detection rate of metastases and lymphoma. iopsy remains necessary for the characterization of larger hemangiomas and other uncommon vascular lesions and when malignancy is suspected JR:186, June 2006

13 MRI of Focal Splenic Lesions Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old boy with acute myeloid leukemia. MRI was performed for staging after positive bone marrow biopsy. and, Unenhanced () and immediate postcontrast () 3D fat-suppressed gradient-echo T1-weighted images show multiple hypovascular nodules (arrows, ) not seen on unenhanced MRI. Nodules became isointense to spleen on delayed acquisition (not shown). Nodules represent chloromas, which tend to be more conspicuous, as in cases of lymphoma, on immediate postcontrast acquisition. In this case, lesions disappeared after chemotherapy. C D Fig year-old woman with treated colon adenocarcinoma and splenic metastasis., xial turbo spin-echo T2-weighted image shows heterogeneous mass with central hyperintense areas. D, xial unenhanced (), immediate postcontrast (C), and 5-min-delayed postcontrast (D) gradient-echo T1-weighted images reveal hypovascular mass on immediate acquisition difficult to detect on delayed acquisition, where remaining central hypovascular area can be seen. Note correlation between nonenhancing areas on delayed postcontrast acquisition and hyperintense areas on T2-weighted images, representing areas of necrosis. JR:186, June

14 Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig. 19 Other splenic lesions., 22-year-old woman with nodular splenomegaly in patient with Niemann-Pick disease type. xial fat-saturated T2-weighted image shows well-defined hypointense splenic nodule (arrow). Hyperintense splenic nodules on T2-weighted images were also seen in same patient (not shown). Diagnosis was established according to imaging and clinical criteria, results of hepatic and bone marrow biopsies, and levels of glucocerebrosidase and sphingomyelinase., 56-year-old man with alcoholic cirrhosis and Gamna-Gandy nodules. xial contrast-enhanced fat-saturated turbo spin-echo T1-weighted image shows cirrhotic liver and multiple millimetric hypointense nodules with associated susceptibility artifact within enlarged spleen. Siderotic nodules represent areas of microhemorrhages. References 1. Runge VM, Williams NM. Dynamic contrast-enhanced magnetic resonance imaging in a model of splenic metastasis. Invest Radiol 1998; 33: Nagasse LL, Richard C, Semelka RC, et al. Spleen. In: Semelka RC. bdomino-pelvic MRI. New York, NY: Wisley-Liss, 2002: Semelka RC, Kelekis NL, Sallah S, Worawattanakul S, scher SM. Hepatosplenic fungal disease: diagnostic accuracy and spectrum of appearances on MR imaging. JR 1997; 169: Robertson F, Leander P, Ekberg O. Radiology of the spleen. Eur Radiol 2001; 11: bbott RM, Levy D, guilera NS, et al. From the archives of the FIP: primary vascular neoplasms of the spleen: radiologic pathologic correlation. RadioGraphics 2004; 24: Ito K, Mitchell DG, Honjo K, et al. MR Imaging of acquired abnormalities of the spleen. JR 1997; 168: Ramani M, Reinhold C, Semelka RC. Splenic hemangiomas and hamartomas: MR imaging characteristics of 28 lesions. Radiology 1997; 202: Hill SC, Damaska M, Ling, et al. Gaucher disease: abdominal MR imaging findings in 46 patients. Radiology 1992; 184: JR:186, June 2006

15 MRI of Focal Splenic Lesions PPENDIX 1: Classification of Focal Splenic Lesions 1. Normal variants ccessory spleen (spleniculi) Splenic notches (fetal lobulations) 2. Polysplenia syndrome Downloaded from by on 01/28/18 from IP address Copyright RRS. For personal use only; all rights reserved 3. Infectious lesions Fungal abscesses acterial abscesses Echinococcosis Healed granulomas 4. Cysts Epithelial (true cysts) Pseudocysts (false cysts) 5. Vascular lesions Focal 1. enign tumors Hemangioma Littoral cell angioma Hemangioendothelioma 2. Malignant neoplasms ngiosarcoma Hemangiopericytoma 3. Nonneoplastic lesions Infarct Hematoma. Diffuse Hemangiomatosis Lymphangiomas, lymphangiomatosis Peliosis 6. Nonvascular tumors. enign Hamartomas Fatty tumors. Malignant Lymphomas Leukemia Metastases 7. Miscellaneous Storage diseases myloidosis Sarcoidosis Gamna-Gandy bodies Inflammatory pseudotumor Extramedullary hematopoiesis JR:186, June