脾脏影像学资料

1,脾脏影像诊断学,放射学院 刘林祥,2,脾脏影像检查技术,X线：价值有限，血管造影USCT：为更清楚显示小病变，可应用5mm的层厚和层距平扫发现可疑应增强,3,MR 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 holdAxial GRE T1WI chemical shift in-phase and out-of-phase imaging performed during a breath holdAxial 3D GRE breath-hold sequence such as volumetric interpolated breath-hold examination (VIBE) with pre-contrast and dynamic enhanced,4,MR Imaging Technique,Lower than liver on T1WI and higher on T2WIImages obtained immediately after enhancement usually demonstrate different circulations as regions of alternating high and low signal intensity, resulting in a serpentine or arciform patternBecomes homogeneous approximately 6090s after contrast material administration,5,Anatomy,The largest ductless gland and the largest single lymphatic organ in the bodymesodermal in originto the circulatory system as the lymph nodes functions include immunologic surveillance, red blood cell breakdown, and splenic contraction for blood volume augmentation during hemorrhageA wide range of pathology can affect the spleen,6,Anatomy,An intraperitoneal organ with a smooth serosal surface and attached to the retroperitoneum by fatty ligamentssurfaces: diaphragmatic (phrenic) and visceral Visceral surface is divided into an anterior or gastric ridge and a posterior or renal portionSplenic artery and vein emerge from the splenic hilum in the form of six or more branches; the splenic artery is remarkable for its large size and tortuosity. slightly superior to the vein,7,Microscopic Anatomy,divided into two compartments, the red and white pulps, separated by the marginal zoneThe white pulp is made up of T and B lymphocytes and located centrallyThe red pulp is composed of rich plexuses of tortuous venous sinuses,8,脾的大小,新月形或内缘凹陷的半月形，密度均匀略低于肝前后径710宽径46上下径1115,9,动脉期强化不均匀静脉期和实质期密度逐渐均匀一致,10,20,60,30,10,Arciform normal enhancement pattern,Axial 3D GRE VIBE Immediately after administration of contrast material Arciform normal enhancement pattern,11,脾的异常CT表现,平扫脾增大数目：多、副、无密度异常低密度：肿瘤、脓肿、囊肿、梗死、挫伤高密度：外伤血肿、错构瘤、钙化,对比增强病灶强化：血管瘤、淋巴瘤、转移瘤环状强化：脓肿病灶无强化：囊肿、梗死,12,MRI影像分析,横断面大小、形态与CT相似冠状面显示脾的大小、形态及其与邻近器官的关系优于横断面T1WI信号低于肝T2WI信号高于肝血管流空无信号,副脾、多脾及异位脾，信号强度始终与脾相同脾肿瘤呈稍长T1长T2信号如肿瘤伴出血坏死，则为混杂信号囊性病变呈圆形长T1低信号和长T2高信号脾内出血的信号与出血时间有关脾内钙化呈黑色低信号,13,Normal Variants: Accessory Spleen,10%Solitary or multiple and no more than 4cmcommon location is the splenic hilum Should distinguished from enlarged LNAxial out-of-phase image Accessory spleen at the hilum,14,Polysplenia,Association with abdominal situs and cardiovascular anomalies. more common in femalesNumerous small splenic masses in hypochondrium Axial in-phase GRE image shows situs inversus with multiple masses in the right upper quadrant,15,Polysplenia,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 quadrant,16,脾外伤,易发生外伤，脾包膜下、脾实质内和脾周围出血据脾破裂时间，早发性脾破裂和迟发性脾破裂可因感染、肿瘤、血液病等引起自发性脾破裂急性脾破裂可出现剧烈左上腹疼痛并向背部放射迟发性脾破裂，症状可隐匿数天至出现大出血,17,脾外伤,平片和透视左上腹脾区致密块影；结肠脾曲因血肿压迫而下移；左膈抬高，活动受限。可伴有其他外伤，如气胸、气腹、肋骨骨折脾动脉造影重度：脾破裂，大血管分支破裂中度：脾内、外有较多的对比剂外溢轻度：脾内血肿，呈小范围无血管区改变或少量对比剂外溢,18,脾外伤CT,脾挫裂伤表现为脾内不规则形的低密度区，还可伴有小点、片状高密度影脾血肿表现为团块状高密度影包膜下血肿呈半月形高密度影，随出血时间延长，血肿逐渐变为等密度乃至低密度灶脾包膜破裂见脾周或并上腹腔积液（积血）增强扫描有助于显示较轻的病变,19,Trauma MRI,Imaging characteristics of splenic hematomas follow those of heme and heme products, with evolution like hematomas in other parts of the bodyCompared to splenic signal intensity, acute hematomas demonstrate prolonged T2. Blood products evolve over time into methemoglobin, deoxyhemoglobin, and other paramagnetic degradation products with concomitant signal intensity changes,20,脾外伤,急性脾破裂CT平扫在稍高密度的膈下液体中见脾轮廓断裂快速注射对比剂，脾的活组织与周围的血液分界清楚,21,脾外伤、破裂,根据脾的形态，提示脾实质裂伤脾周液体的CT值超过50HU，表明腹腔内存在出血,22,脾外伤,脾血肿被膜下血肿在注射对比剂后清晰,23,24,25,26,Trauma,Coronal T2WIhalf-Fourier RAREC- 3D VIBE An acute or subacute subcapsular hematoma,27,脾肿瘤,原发脾肿瘤少见，恶性以淋巴瘤多，良性以血管瘤多脾恶性淋巴瘤CT可见脾增大，脾内单发或多发稍低密度灶，边界不清。增强扫描病灶轻度不规则强化，与正常脾实质分界清楚脾海绵状血管瘤CT平扫为边界清楚的低密度区，增强早期显示病灶周边结节状强化，延迟扫描对比剂逐渐向中心充填，最后病灶呈等密度脾血管瘤在T2WI呈明显高信号，Gd-DTPA增强多明显强化。淋巴瘤表现为单个或多个大小不等的圆形肿块，边界不清，在T1WI及T2WI表现为不均匀性混杂信号,28,Inflammation,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 multilocularLow signal intensity on T1WI and high signal intensity on T2WIMinimal peripheral enhancement when the capsule develops,29,Inflammation,Splenic abscessAxial T2W IRE+ T1WI fast multiplanar spoiled GREAIDShyperintense on T2WI hypointense on T1WI,30,Candidiasis,The most common infection involving the liver and spleen in immunocompromised MRI be superior to CT in detection of microabscesses secondary to candidiasismultiple hypointense, ring-enhancing lesions less than 1 cm on enhanced images,31,Candidiasis,E+ 3D VIBEimmunocompromisedMultiple small, hypointense lesions,32,Histoplasmosis,Although seen in patients with competent immune systems, the prevalence of histoplasmosis is greater in immunocompromised patientsMRI demonstrates the acute and subacute phases of disease as scattered hypointense lesions on both T1WI and T2WIOld granulomas can be calcified, causing characteristic signal intensity changes with blooming artifacts on MRIThis appearance is best appreciated on GRE T1WI, especially those obtained with a long echo time,33,Histoplasma capsulatum,Axial E+ 3D VIBET2WI IR Scattered low signal intensity lesionsrepresent infection of spleen,34,Axial T1WI and T2WIold calcified splenic histoplasmomaA low signal ntensity lesion with characteristic blooming,35,Sarcoidosis,A granulomatous systemic disease of unknown etiology that can involve numerous sites, infrequently involving the spleenNodular sarcoidosis demonstrate low signal intensity with all MRI sequencesLesions are most conspicuous on T2WI FS or early phase enhanced imagesSarcoidosis lesions enhance in a minimal and delayed pattern,36,Sarcoidosis,multiple small, hypointense, focal splenic lesions, represent sarcoidosisnot enhance on early phase but enhance on delayed phase,37,脾肿瘤,非何杰金淋巴瘤平扫见脾大注射对比剂后可见多发低密度区,38,非何杰金淋巴瘤,境界清楚的低密度病灶，注射对比剂后周边强化,39,非何杰金淋巴瘤,多发微小低密度病灶，对比增强后清楚化学治疗后消失,40,41,42,43,脾囊肿,分为先天性和后天性，真性和假性真性囊肿见于单纯性囊肿和多囊脾，假性囊肿见于外伤出血和炎症之后。脾包虫囊肿多见于流行区CT和MRI表现类似于肝肾囊肿寄生虫性囊肿常可见囊肿壁弧形钙化，外伤性囊肿内由于出血和机化，囊内密度高于水,44,脾囊肿,囊肿壁钙化，考虑为寄生虫性,45,Benign Neoplasms or Cysts,True splenic cysts are epithelial cell lined, as opposed to pseudocystsInclude epidermoid and parasitic cystsMRI characteristics follow those of cysts in other organs of the body, with lack of tissue architecture and high water contentlonger T1 and T2 relative to normal splenic tissueno enhancement following administration of GDDTPA MRI is useful when US and CT results are equivocal,46,Splenic cyst,Axial E+ T1WI 3D VIBE T2WI half-Fourier RARETypical features,47,脾梗死,常见原因是左心系统血栓脱落，脾周围器官的肿瘤和炎症引起脾动脉血栓并脱落，某些血液病和淤血性脾增大多无症状，少数可有上腹疼痛脾动脉造影见受累动脉中断，并见三角形无血管区，尖端指向脾门MRI梗塞区的信号强度根据梗塞时间长短不同急性和亚急性梗塞区在T1WI和T2WI分别为低信号和高信号区慢性期梗塞区瘢痕和钙化形成，T1WI和T2WI均为低信号,48,脾梗死,CT脾内三角形低密度影，尖端指向脾门，边界清楚。增强后无强化快速注射对比剂，肿大的脾内可见局限性低密度区，脾被膜轻度凹陷,49,脾梗死,脾脏完全梗死，周围脾实质接受被膜血管的血供,50,Splenic Infarction,Seen in the setting of arterial emboli such as in sickle cell anemia, Gaucher disease, hematologic malignancies, cardiac emboli, torsion, collagen vascular disease, and portal hypertensionPeripheral wedge-shaped defects that exhibit decreased signal intensity on both T1WI and T2WI and do not enhance after intravenous contrast material administration,51,Splenic Infarction,Axial E+ 3D VIBE nonenhancing wedge-shaped area of infarction,52,Splenic artery aneurysms,Secondary to multiple causes such as medial degeneration with superimposed atherosclerosis, congenital causes, mycotic causes, portal hypertension, fibromuscular dysplasia, and pseudoaneurysms from trauma and pancreatitisMRI allows effective diagnosis and characterization of these lesions3D GRE sequences such as VIBE or dedicated 3D MR angiographic sequences are the best for evaluating these lesions,53,Splenic artery aneurysms,E+ 3D GRE VIBEAneurysmal dilatation of distal end of splenic artery,54,Splenic vein thrombosis,Most commonly secondary to pancreatitisAt least 20% with chronic pancreatitisCompression and fibrosis caused by pancreatitisErosion of a pseudocyst into the splenic veinMay result in gastric varices and at times either esophageal or colonic varicesan intraluminal filling defect after iv. contrastE+ MRA has the potential to replace ia. DSA as the standard method of assessing the portal venous anatomy,55,Splenic vein thrombosis,Axial venous phase E+ 3D GRE VIBE Thrombus filling the splenic vein Appears as an area of signal void,56,Arteriovenous malformations,Can occur anywhere in the human body but rarely occur in the spleenA 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 malformations as multiple signal voids with all nonenhanced pulse sequencesArteriovenous malformations demonstrate serpentine enhancement after intravenous injection of gadolinium contrast material,57,Arteriovenous malformations,Axial T2-weighted inversion-recovery and contrast-enhanced 3D VIBE imagesA splenic lesion that appears as an area of signal voidThe lesion demonstrates serpentine enhancement on the enhanced image and represents an arteriovenous malformation,58,Hematologic DisordersSickle Cell Disease,Common in the black population with a prevalence of 0.2% (homozygous form) and 8%10% (heterozygous form)The spleen is the organ most commonly involved by sickle cell diseaseAppears as a nearly signal void area due to iron deposition from blood transfusion Autosplenectomy is often found in patients with homozygous sickle cell disease,59,Sickle Cell Disease,T2WI half-Fourier RAREDecreased signal intensity is due to repeated blood transfusion,60,Sickle Cell Disease,Axial E+T1WI GRE A very small spleen is indicative of autosplenectomy,61,Extramedullary hematopoiesis,A compensatory response to deficient bone marrow cells predominantly affects the spleen and liverAlthough usually shows diffuse infiltration microscopically, may be focal masslike involvement of liver and spleenSignal intensity depends on evolution of hematopoiesisActive lesions show intermediate signal intensity on T1WI, high signal intensity on T2WI, and some enhancement Older lesions show low signal intensity on T1WI and T2WI and may not show any enhancementusually exhibit reduced signal intensity on in-phase T1WI GRE compared with that on opposed-phase images owing to the presence of iron,62,Extramedullary hematopoiesis,The lesion has reduced signal intensity on the in-phase image compared with that on the out-of-phase imageThis difference is secondary to iron deposition,63,Hemangioma,The most common primary benign neoplasm of the spleenComposed of endothelium-lined vascular channels filled with bloodMost are hypointense to the spleen on T1WI and hyperintense on T2WIEarly nodular centripetal enhancement and uniform enhancement at delayed imaging,64,Splenic hemangioma,Axial T2WI FSE and E+ 3D VIBETypical MRI features,65,Diffuse hemangiomatosis,A rare benign vascular condition occurring as a manifestation of systemic angiomatosisAssociations with Klippel-Trnaunay-Weber, Turner, Kasabach-Merrittlike, and Beckwith-Wiedemann syndromes less commonly, confined to the spleenSometimes accompanied by severe disturbance of blood coagulation,66,Axial E+ 3D VIBE and T2WI of a Klippel-Trnaunay-Weber syndromeDiffuse angiomatosis of the spleen and chest wall,67,Hamartomas,Benign asymptomatic lesions, usually single, composed of a mixture of normal splenic structures such as white and red pulpCommonly associated with tuberous sclerosisHeterogeneously hyperintense relative to the spleen on T2WI and demonstrate diffuse enhancement on early postcontrast images and more uniform enhancement on delayed images,68,Hamartomas,Lesion with high signal intensity on T2WI, low signal intensity on T1WI, and more uniform enhancement on the delayed image,69,Splenic Sarcoma,Primary splenic angiosarcomas are extremely rare tumors with a very poor prognosis. highly aggressive and manifest with wide-spread metastatic disease or splenic ruptureLow signal intensity on T1WI and heterogeneous high signal intensity on T2WIHeterogeneous 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 particular value for timely diagnosis of this rapidly fatal disease,70,Angiosarcoma,E+ 3D VIBET2WI half-Fourier RARE Low on T1WIHigh on T2WIHeterogeneous enhancement,71,Lymphoma,The commonest malignant tumor of the spleenIt is important to detect splenic involvement because it can alter the managementLymphomatous deposits have T1 and T2 similar to those of normal splenic parenchymaEnhanced sequences are more sensitive for the evaluation of splenic lymphomaDiffuse involvement may be seen as large irregularly enhancing regionsMultifocal disease is also common and can be seen as multiple focal lesions that are hypointense relative to the uniformly or arciform enhancing spleen,72,Lymphoma,E+ 3D GRE VIBE Multifocal involvement of the spleen by multiple hypointense lymphomatous lesions,73,Metastases,Relatively uncommonUsually in widespread disseminated malignanciesIsolated splenic metastases also recognizedTypically as hyperintense masses on T2WI and hypo- to isointense masses on T1WIThe degree and characteristics of enhancement depend on the nature and type of the underlying primary neoplasm,74,Metastases,T2-WI half-Fourier RAREA patient who underwent left nephrectomy for renal cell carcinoma shows hyperintense splenic metastases,75,Splenic enlargement,Caused by various diseasesLymphomaMalariaLeukemiaportal hypertensionmetabolic diseases (eg, Gaucher disease),76,Portal hypert