1、1脾臟影像診斷學2脾臟影像檢查技術 X線：價值有限，血管造影 US CT：為更清楚顯示小病變，可應用5mm的層厚和層距 平掃發現可疑應增強3MR Imaging Technique Coronal T2WI half-Fourier rapid acquisition with relaxation enhancement (RARE) Axial FSE T2WI or long echo time inversion-recovery imaging performed during a breath hold Axial GRE T1WI chemical shift in-phase

2、and out-of-phase imaging performed during a breath hold Axial 3D GRE breath-hold sequence such as volumetric interpolated breath-hold examination (VIBE) with pre-contrast and dynamic enhanced4MR Imaging Technique Lower than liver on T1WI and higher on T2WI Images obtained immediately after enhanceme

3、nt usually demonstrate different circulations as regions of alternating high and low signal intensity, resulting in a serpentine or arciform pattern Becomes homogeneous approximately 6090s after contrast material administration 5Anatomy The largest ductless gland and the largest single lymphatic org

4、an in the body mesodermal in origin to the circulatory system as the lymph nodes functions include immunologic surveillance, red blood cell breakdown, and splenic contraction for blood volume augmentation during hemorrhage A wide range of pathology can affect the spleen6Anatomy An intraperitoneal or

5、gan with a smooth serosal surface and attached to the retroperitoneum by fatty ligaments surfaces: diaphragmatic (phrenic) and visceral Visceral surface is divided into an anterior or gastric ridge and a posterior or renal portion Splenic artery and vein emerge from the splenic hilum in the form of

6、six or more branches; the splenic artery is remarkable for its large size and tortuosity. slightly superior to the vein 7Microscopic Anatomy divided into two compartments, the red and white pulps, separated by the marginal zone The white pulp is made up of T and B lymphocytes and located centrally T

7、he red pulp is composed of rich plexuses of tortuous venous sinuses 8脾的大小 新月形或內緣凹陷的半月形，密度均勻略低于肝 前后徑710 寬徑46 上下徑11159動脈期強化不均勻靜脈期和實質期密度逐漸均勻一致1020603010Arciform normal enhancement pattern Axial 3D GRE VIBE Immediately after administration of contrast material Arciform normal enhancement pattern11脾的異常CT

8、表現平掃平掃 脾增大 數目：多、副、無 密度異常 低密度：腫瘤、膿腫、囊腫、梗死、挫傷 高密度：外傷血腫、錯構瘤、鈣化對比增強對比增強 病灶強化：血管瘤、淋巴瘤、轉移瘤 環狀強化：膿腫 病灶無強化：囊腫、梗死12MRI影像分析 橫斷面大小、形態與CT相似 冠狀面顯示脾的大小、形態及其與鄰近器官的關系優于橫斷面 T1WI信號低于肝 T2WI信號高于肝 血管流空無信號 副脾、多脾及異位脾，信號強度始終與脾相同 脾腫瘤呈稍長T1長T2信號 如腫瘤伴出血壞死，則為混雜信號 囊性病變呈圓形長T1低信號和長T2高信號 脾內出血的信號與出血時間有關 脾內鈣化呈黑色低信號13Normal Variants:

9、Accessory Spleen 10% Solitary or multiple and no more than 4cm common location is the splenic hilum Should distinguished from enlarged LN Axial out-of-phase image Accessory spleen at the hilum 14Polysplenia Association with abdominal situs and cardiovascular anomalies. more common in females Numerou

10、s small splenic masses in hypochondrium Axial in-phase GRE image shows situs inversus with multiple masses in the right upper quadrant15Polysplenia Coronal GRE cine and axial in-phase GRE images A cardiac anomaly in the form of pulmonary stenosis and small masses in the left upper quadrant16脾外傷易發生外傷

11、，脾包膜下、脾實質內和脾周圍出血據脾破裂時間，早發性脾破裂和遲發性脾破裂可因感染、腫瘤、血液病等引起自發性脾破裂急性脾破裂可出現劇烈左上腹疼痛并向背部放射遲發性脾破裂，癥狀可隱匿數天至出現大出血17脾外傷平片和透視左上腹脾區致密塊影；結腸脾曲因血腫壓迫而下移；左膈抬高，活動受限。可伴有其他外傷，如氣胸、氣腹、肋骨骨折脾動脈造影重度：脾破裂，大血管分支破裂中度：脾內、外有較多的對比劑外溢輕度：脾內血腫，呈小范圍無血管區改變或少量對比劑外溢18脾外傷CT脾挫裂傷表現為脾內不規則形的低密度區，還可伴有小點、片狀高密度影脾血腫表現為團塊狀高密度影包膜下血腫呈半月形高密度影，隨出血時間延長，血腫逐漸變為

12、等密度乃至低密度灶脾包膜破裂見脾周或并上腹腔積液（積血）增強掃描有助于顯示較輕的病變19Trauma MRI Imaging characteristics of splenic hematomas follow those of heme and heme products, with evolution like hematomas in other parts of the body Compared to splenic signal intensity, acute hematomas demonstrate prolonged T2. Blood products evolve o

13、ver time into methemoglobin, deoxyhemoglobin, and other paramagnetic degradation products with concomitant signal intensity changes20脾外傷 急性脾破裂 CT平掃在稍高密度的膈下液體中見脾輪廓斷裂 快速注射對比劑，脾的活組織與周圍的血液分界清楚21脾外傷、破裂 根據脾的形態，提示脾實質裂傷 脾周液體的CT值超過50HU，表明腹腔內存在出血22脾外傷 脾血腫 被膜下血腫在注射對比劑后清晰23242526Trauma Coronal T2WI half-Fourier

14、 RARE C- 3D VIBE An acute or subacute subcapsular hematoma 27脾腫瘤 原發脾腫瘤少見，惡性以淋巴瘤多，良性以血管瘤多 脾惡性淋巴瘤CT可見脾增大，脾內單發或多發稍低密度灶，邊界不清。增強掃描病灶輕度不規則強化，與正常脾實質分界清楚 脾海綿狀血管瘤CT平掃為邊界清楚的低密度區，增強早期顯示病灶周邊結節狀強化，延遲掃描對比劑逐漸向中心充填，最后病灶呈等密度 脾血管瘤在T2WI呈明顯高信號，Gd-DTPA增強多明顯強化。淋巴瘤表現為單個或多個大小不等的圓形腫塊，邊界不清，在T1WI及T2WI表現為不均勻性混雜信號28Inflammation

15、 Abscesses be found in 0.14-0.7% autopsy cases Prevalence increased due to increased number of immunosuppressed patients such as AIDS Solitary, multiple, or multilocular Low signal intensity on T1WI and high signal intensity on T2WI Minimal peripheral enhancement when the capsule develops 29Inflamma

16、tion Splenic abscess Axial T2W IR E+ T1WI fast multiplanar spoiled GRE AIDS hyperintense on T2WI hypointense on T1WI 30Candidiasis The most common infection involving the liver and spleen in immunocompromised MRI be superior to CT in detection of microabscesses secondary to candidiasis multiple hypo

17、intense, ring-enhancing lesions less than 1 cm on enhanced images 31Candidiasis E+ 3D VIBE immunocompromised Multiple small, hypointense lesions32Histoplasmosis Although seen in patients with competent immune systems, the prevalence of histoplasmosis is greater in immunocompromised patients MRI demo

18、nstrates the acute and subacute phases of disease as scattered hypointense lesions on both T1WI and T2WI Old granulomas can be calcified, causing characteristic signal intensity changes with blooming artifacts on MRI This appearance is best appreciated on GRE T1WI, especially those obtained with a l

19、ong echo time 33Histoplasma capsulatum Axial E+ 3D VIBE T2WI IR Scattered low signal intensity lesions represent infection of spleen34 Axial T1WI and T2WI old calcified splenic histoplasmoma A low signal ntensity lesion with characteristic blooming 35Sarcoidosis A granulomatous systemic disease of u

20、nknown etiology that can involve numerous sites, infrequently involving the spleen Nodular sarcoidosis demonstrate low signal intensity with all MRI sequences Lesions are most conspicuous on T2WI FS or early phase enhanced images Sarcoidosis lesions enhance in a minimal and delayed pattern 36Sarcoid

21、osis multiple small, hypointense, focal splenic lesions, represent sarcoidosis not enhance on early phase but enhance on delayed phase 37脾腫瘤 非何杰金淋巴瘤 平掃見脾大 注射對比劑后可見多發低密度區38非何杰金淋巴瘤 境界清楚的低密度病灶，注射對比劑后周邊強化39非何杰金淋巴瘤 多發微小低密度病灶，對比增強后清楚 化學治療后消失40414243脾囊腫 分為先天性和后天性，真性和假性 真性囊腫見于單純性囊腫和多囊脾，假性囊腫見于外傷出血和炎癥之后。脾包蟲囊腫

22、多見于流行區 CT和MRI表現類似于肝腎囊腫 寄生蟲性囊腫常可見囊腫壁弧形鈣化，外傷性囊腫內由于出血和機化，囊內密度高于水44脾囊腫 囊腫壁鈣化，考慮為寄生蟲性45Benign Neoplasms or Cysts True splenic cysts are epithelial cell lined, as opposed to pseudocysts Include epidermoid and parasitic cysts MRI characteristics follow those of cysts in other organs of the body, with lack

23、of tissue architecture and high water content longer T1 and T2 relative to normal splenic tissue no enhancement following administration of GDDTPA MRI is useful when US and CT results are equivocal 46Splenic cyst Axial E+ T1WI 3D VIBE T2WI half-Fourier RARE Typical features47脾梗死常見原因是左心系統血栓脫落，脾周圍器官的腫

24、瘤和炎癥引起脾動脈血栓并脫落，某些血液病和淤血性脾增大多無癥狀，少數可有上腹疼痛脾動脈造影見受累動脈中斷，并見三角形無血管區，尖端指向脾門MRI梗塞區的信號強度根據梗塞時間長短不同急性和亞急性梗塞區在T1WI和T2WI分別為低信號和高信號區慢性期梗塞區瘢痕和鈣化形成，T1WI和T2WI均為低信號48脾梗死 CT脾內三角形低密度影，尖端指向脾門，邊界清楚。增強后無強化 快速注射對比劑，腫大的脾內可見局限性低密度區，脾被膜輕度凹陷49脾梗死 脾臟完全梗死，周圍脾實質接受被膜血管的血供50Splenic Infarction Seen in the setting of arterial embol

25、i such as in sickle cell anemia, Gaucher disease, hematologic malignancies, cardiac emboli, torsion, collagen vascular disease, and portal hypertension Peripheral wedge-shaped defects that exhibit decreased signal intensity on both T1WI and T2WI and do not enhance after intravenous contrast material

26、 administration 51Splenic Infarction Axial E+ 3D VIBE nonenhancing wedge-shaped area of infarction 52Splenic artery aneurysms Secondary to multiple causes such as medial degeneration with superimposed atherosclerosis, congenital causes, mycotic causes, portal hypertension, fibromuscular dysplasia, a

27、nd pseudoaneurysms from trauma and pancreatitis MRI allows effective diagnosis and characterization of these lesions 3D GRE sequences such as VIBE or dedicated 3D MR angiographic sequences are the best for evaluating these lesions 53Splenic artery aneurysms E+ 3D GRE VIBE Aneurysmal dilatation of di

28、stal end of splenic artery54Splenic vein thrombosis Most commonly secondary to pancreatitis At least 20% with chronic pancreatitis Compression and fibrosis caused by pancreatitis Erosion of a pseudocyst into the splenic vein May result in gastric varices and at times either esophageal or colonic var

29、ices an intraluminal filling defect after iv. contrast E+ MRA has the potential to replace ia. DSA as the standard method of assessing the portal venous anatomy 55Splenic vein thrombosis Axial venous phase E+ 3D GRE VIBE Thrombus filling the splenic vein Appears as an area of signal void 56Arteriove

30、nous malformations Can occur anywhere in the human body but rarely occur in the spleen A machinery-type bruit in the upper left abdominal quadrant represents an important and simple diagnostic symptom found at clinical examination during auscultation MR imaging can demonstrate arteriovenous malforma

31、tions as multiple signal voids with all nonenhanced pulse sequences Arteriovenous malformations demonstrate serpentine enhancement after intravenous injection of gadolinium contrast material 57Arteriovenous malformationsAxial T2-weighted inversion-recovery and contrast-enhanced 3D VIBE imagesA splen

32、ic lesion that appears as an area of signal voidThe lesion demonstrates serpentine enhancement on the enhanced image and represents an arteriovenous malformation 58Hematologic DisordersSickle Cell Disease Common in the black population with a prevalence of 0.2% (homozygous form) and 8%10% (heterozyg

33、ous form) The spleen is the organ most commonly involved by sickle cell disease Appears as a nearly signal void area due to iron deposition from blood transfusion Autosplenectomy is often found in patients with homozygous sickle cell disease 59Sickle Cell Disease T2WI half-Fourier RARE Decreased sig

34、nal intensity is due to repeated blood transfusion 60Sickle Cell Disease Axial E+T1WI GRE A very small spleen is indicative of autosplenectomy 61Extramedullary hematopoiesis A compensatory response to deficient bone marrow cells predominantly affects the spleen and liver Although usually shows diffu

35、se infiltration microscopically, may be focal masslike involvement of liver and spleen Signal intensity depends on evolution of hematopoiesis Active lesions show intermediate signal intensity on T1WI, high signal intensity on T2WI, and some enhancement Older lesions show low signal intensity on T1WI

36、 and T2WI and may not show any enhancement usually exhibit reduced signal intensity on in-phase T1WI GRE compared with that on opposed-phase images owing to the presence of iron62Extramedullary hematopoiesis The lesion has reduced signal intensity on the in-phase image compared with that on the out-

37、of-phase image This difference is secondary to iron deposition 63Hemangioma The most common primary benign neoplasm of the spleen Composed of endothelium-lined vascular channels filled with blood Most are hypointense to the spleen on T1WI and hyperintense on T2WI Early nodular centripetal enhancemen

38、t and uniform enhancement at delayed imaging 64Splenic hemangioma Axial T2WI FSE and E+ 3D VIBE Typical MRI features65Diffuse hemangiomatosis A rare benign vascular condition occurring as a manifestation of systemic angiomatosis Associations with Klippel-Trnaunay-Weber, Turner, Kasabach-Merrittlike,

39、 and Beckwith-Wiedemann syndromes less commonly, confined to the spleen Sometimes accompanied by severe disturbance of blood coagulation 66 Axial E+ 3D VIBE and T2WI of a Klippel-Trnaunay-Weber syndrome Diffuse angiomatosis of the spleen and chest wall67Hamartomas Benign asymptomatic lesions, usuall

40、y single, composed of a mixture of normal splenic structures such as white and red pulp Commonly associated with tuberous sclerosis Heterogeneously hyperintense relative to the spleen on T2WI and demonstrate diffuse enhancement on early postcontrast images and more uniform enhancement on delayed ima

41、ges 68Hamartomas Lesion with high signal intensity on T2WI, low signal intensity on T1WI, and more uniform enhancement on the delayed image69 Splenic Sarcoma Primary splenic angiosarcomas are extremely rare tumors with a very poor prognosis. highly aggressive and manifest with wide-spread metastatic

42、 disease or splenic rupture Low signal intensity on T1WI and heterogeneous high signal intensity on T2WI Heterogeneous enhancement with multiple hyperintense nodular foci and hypointense regions MRI seems to be more precise in the overall assessment and staging of this type of tumor and is of partic

43、ular value for timely diagnosis of this rapidly fatal disease 70Angiosarcoma E+ 3D VIBE T2WI half-Fourier RARE Low on T1WI High on T2WI Heterogeneous enhancement71Lymphoma The commonest malignant tumor of the spleen It is important to detect splenic involvement because it can alter the management Ly

44、mphomatous deposits have T1 and T2 similar to those of normal splenic parenchyma Enhanced sequences are more sensitive for the evaluation of splenic lymphoma Diffuse involvement may be seen as large irregularly enhancing regions Multifocal disease is also common and can be seen as multiple focal les

45、ions that are hypointense relative to the uniformly or arciform enhancing spleen 72Lymphoma E+ 3D GRE VIBE Multifocal involvement of the spleen by multiple hypointense lymphomatous lesions 73Metastases Relatively uncommon Usually in widespread disseminated malignancies Isolated splenic metastases al

46、so recognized Typically as hyperintense masses on T2WI and hypo- to isointense masses on T1WI The degree and characteristics of enhancement depend on the nature and type of the underlying primary neoplasm 74Metastases T2-WI half-Fourier RARE A patient who underwent left nephrectomy for renal cell carcinoma shows hyperintense splenic metastases 75Splenic enlargement Caused by various diseases Lymphoma Malaria Leukemia portal hypertension metabolic diseases (eg, Gaucher disease) 76Portal hypertens