The clinical utility of nuclear medicine imaging for the detection of occult gastrointestinal haemorrhage

Acute gastrointestinal bleeding is often intermittent and the bleeding source may be difficult to locate, resulting in delay of potentially life-saving treatment. The aim of this study was to determine the clinical utility of 99mTc labelled red blood cell imaging and [99mTc]pertechnetate (Meckel's scan) imaging in a series of 137 patients admitted over a 5 year period to hospital for management of acute gastrointestinal bleeding. Of the 137 patients, 70 had positive 99mTc red blood cell studies. Eleven of 24 patients who had imaging performed beyond 3 h had positive scans that would otherwise have been missed. Only 47 patients had a definite final diagnosis at the time of hospital discharge, of which six were negative on 99mTc red blood cell imaging. The correct site of bleeding was localized in seven of 21 patients with foregut bleeding, and 15 of 20 patients with colonic bleeding. Endoscopy yielded a diagnosis in 13 of the 47 patients (28%). Eleven patients had Meckel's scans but all were negative. Angiography was diagnostic in one of 17 patients studied. 99mTc red blood cell imaging is a useful test in the management of acute gastrointestinal bleeding. Imaging beyond 3 h may further improve the bleeding detection rate. This test, however, may be an unreliable means of localization of bleeding, particularly in the foregut.     

Distribution of cranial MRI abnormalities in patients with symptomatic and subclinical CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare, inherited cause of early stroke and dementia, with a poor prognosis. This study was performed to clarify lesion appearance and pattern of lesion distribution in CADASIL. 20 members of a single family were tested for the CADASIL gene mutation and studied with cranial MRI. Scans were evaluated for lesion load and pattern of lesion distribution. 19 patients had cranial MRI, of whom 11 had normal MRI scans, were clinically unaffected and tested negative for the CADASIL gene mutation. The remaining eight patients had abnormal cranial MRI scans: seven patients were positive for the CADASIL gene mutation and one (untested) patient was severely clinically affected. Three of the patients who tested positive for the CADASIL gene mutation were clinically unaffected at the time of imaging. All eight patients with abnormal cranial MRI had subcortical white matter abnormalities, mostly in frontal and temporal lobes. Lesions involving the corpus callosum were present on sagittal T2 weighted images in four of five clinically affected and one of three clinically unaffected patients. Lesions involving the deep grey nuclei and the brain stem were common. On T1 weighted images, lesions were either poorly defined (confluent white matter hypointensity) or well defined (cystic infarcts or enlarged perivascular spaces). Atrophy was infrequent. Familiarity with the range of cranial MRI appearances may aid diagnosis of CADASIL. Recognition of cranial imaging features in asymptomatic CADASIL patients could prompt earlier diagnosis.     

MR扩散加权成像在甲状腺疾病诊断及监测中的应用研究进展

甲状腺疾病是临床常见的疾病,在内分泌系统疾病发病率最高,早发现、早诊断对指导临床治疗具有重要意义,其影像诊断是临床和影像科医生关注的重点和难点。MR扩散加权成像通过检测水分子扩散运动可实现对器官结构及功能改变的检测,近年来MR扩散加权成像在甲状腺疾病中诊断及监测的应用价值越来越受到认可。对近5年扩散加权成像技术的发展及其在甲状腺疾病中的应用作一综述。     

动脉自旋标记MRI脑血流灌注成像在亚临床期肝性脑病患者的研究

目的 用动脉自旋标记(ASL)MRI灌注成像技术评价亚临床肝性脑病(SHE)患者基底节区的脑血流灌注模式.方法 对16例经神经心理试验诊断为SHE的患者和13例年龄和教育程度相匹配的健康志愿者进行MRI平扫和ASL灌注成像,分别测量双侧尾状核头、苍白球、壳核、丘脑和额叶白质的脑血流量(CBF),并以同侧额叶白质作为参照进行统计分析.结果 SHE患者各感兴趣区与白质的比值均高于对照组:CBF值右侧分别为0.88±0.17,1.01±0.06,0.96±0.13和0.93±0.10,左侧分别0.91±0.15,1.00±0.07,0.94±0.12和0.97±0.11,志愿者相应部位CBF值右侧分别为0.81±0.04,0.95±0.04,0.88±0.04和0.90±0.04,左侧分别为0.81±0.02,0.94±0.04,0.87±0.05和0.92±0.04.结论 ASL脑血流灌注成像探测到SHE患者基底节区的脑血流灌注是增加的.SHE患者基底节区灌注增加是血流从皮质到基底节区的重新分布.     

The clinical role of nuclear medicine in rheumatoid arthritis patients. A comparison with other diagnostic imaging modalities.

In patients with rheumatoid arthritis (RA) synovitis activity is the dominant clinical variable that determines the therapeutic approach. At present, the amount of painful and swollen joints assessed by physical examination, is generally used to measure the degree of synovitis activity. A gold standard for the assessment of synovitis activity is not available. The availability of an objective and reproducible method to evaluate synovitis activity in RA would be of great value in patient management and in examination of therapeutic effects. An advantage of the use of radiopharmaceuticals in detection of arthritis activity, compared with other imaging techniques, is the possibility to depict all joints in a single image. Furthermore the technique may image joints which are difficult to assess clinically or radiographically and may also detect joint inflammation in an early phase. In this overview different scintigraphic techniques are compared with each other and with other diagnostic imaging modalities.     

Pulmonary abnormalities in immunocompromised patients: comparative detection with parallel acquisition MR imaging and thin-section helical CT

PURPOSE: To compare parallel acquisition magnetic resonance (MR) imaging with thin-section helical computed tomography (CT) for depiction of pulmonary abnormalities suggestive of pneumonia in immunocompromised patients. MATERIALS AND METHODS: The institutional review board approved this study; prior consent was obtained. Thirty consecutive neutropenic patients (10 women, 20 men; mean age, 51 years +/- 15 [standard deviation]; range, 25-75 years) with fever of unknown origin or clinical signs and symptoms of lung infection were examined with breath-hold single-shot half-Fourier turbo spin-echo MR imaging. To reduce image blurring and increase MR signal in the lungs, the echo time was shortened with generalized autocalibrating partially parallel acquisition (GRAPPA). Patients underwent thoracic CT (four detector rows and 1-mm section thickness [4 x 1 mm]; pitch, 6) as reference standard. Pulmonary abnormalities (ill-defined nodules, ground-glass opacity areas, and consolidation), their location and distribution, and lesion characteristics were analyzed at MR imaging by three readers, blinded to results of CT, in consensus. Frequencies were calculated for each feature; paired Wilcoxon rank sum test was used to examine whether differences between CT and MR imaging features were statistically significant (alpha < .05). Bonferroni adjustments were performed. Overall sensitivity, specificity, and positive and negative predictive values were determined. RESULTS: Twenty-two patients had pulmonary abnormalities at CT. In 21 (95%) patients, pneumonia was correctly diagnosed with MR imaging. One false-negative finding occurred in a patient with ill-defined nodules smaller than 1 cm at CT. One false-positive finding with MR imaging was the result of blurring and respiratory artifacts (sensitivity, 95%; specificity, 88%; positive predictive value, 95%; negative predictive value, 88%). There was no significant difference in lesion location and distribution. CONCLUSION: With parallel imaging (GRAPPA technique) and fast MR imaging, detection of pulmonary abnormalities is almost as good as with CT. MR imaging has a slight disadvantage in its lower capability to assist in characterization of specific internal features, such as cavitations.     

MR脑血流灌注成像在亚临床肝性脑病中的应用

目的用MR灌注成像技术评价亚临床肝性脑病(SHE)患者的脑血流灌注模式。方法对12例经神经心理试验诊断为SHE的患者和10例年龄和教育程度相匹配的健康志愿者进行MR平扫和灌注成像,分别测量双侧尾状核头、苍白球、壳核、丘脑和额叶白质的脑血容量(CBV)、脑血流量(CBF)和平均通过时间(MTT),并以同侧额叶脑白质作为参照进行统计分析。结果SHE患者各感兴趣区与白质的比值:CBV值分别是1.32±0.25、1.19±0.46、1.51±0.20、1.69±0.53;CBF值分别为1.64±0.50、1.61±0.65、2.06±0.61、2.23±0.75;MTT值分别是0.83±0.17、0.76±0.20、0.78±0.19、0.78±0.17。志愿者相应部位CBV值为1.32±0.33、1.02±0.29、1.44±0.37、1.66±0.57;CBF值为1.36±0.24、1.08±0.28、1.55±0.51、1.58±0.64;MTT值为0.95±0.18、0.91±0.19、0.93±0.15、0.93±0.13。SHE患者较正常组MTT明显缩短,双侧丘脑、右侧尾状核头达到统计学意义的降低(P<0.05);CBF明显升高,左侧苍白球达到统计学意义的升高(P<0.05);CBV无明显变化。结论SHE患者基底节区灌注增加是血流从皮质到基底节区的重新分布,这是对运动前区、运动区功能缺陷及注意力缺陷的代偿反应,与皮质-基底节-丘脑-皮质环路密切相关。     

Diffusion-weighted imaging of white matter abnormalities in patients with phenylketonuria

Phenylketonuria (PKU) is an autosomal recessive disorder caused by a deficiency of the enzyme phenylalanine hydroxylase (EC 1.14.16.1). Affected patients develop elevated plasma and tissue levels of phenylalanine and its related ketoacids. Untreated patients usually exhibit severe mental retardation and poor motor function, with characteristic T2 white matter signal abnormalities on conventional MR images. In the present study, we performed diffusion-weighted imaging in three PKU patients. All three patients demonstrated significantly restricted diffusion in all white matter areas examined.     

Scintigraphic studies in patients with medullary carcinoma of the thyroid

Findings on pre-operative thyorid scintiscans in 29 patients with medullary carcinoma of the thyroid were compared with results of palpation and pathological findings. Six patients had a normal uptake of ¹³¹I or ^99mTc in tumours 1.5–8 cm in diameter. When compared with 111 pre-operative scintiscans in other thyroid carcinomas, the frequency of normal uptake in medullary carcinomas was high, 19% versus 0–6%. Gallium-67 scintiscans were performed in nine patients. Six patients had extensive tumours, but accumulation of ⁶⁷Ga appeared in only one patient.     

Scintigraphic studies in patients with medullary carcinoma of the thyroid

Findings on pre-operative thyroid scintiscans in 29 patients with medullary carcinoma of the thyroid were compared with results of palpation and pathological findings. Six patients had a normal uptake of 131I or 99mTc in tumours 1.5--8 cm in diameter. When compared with 111 pre-operative scintiscans in other thyroid carcinomas, the frequency of normal uptake in medullary carcinomas was high, 19% versus 0--6%. Gallium-67 scintiscans were performed in nine patients. Six patients had extensive tumours, but accumulation of 67Ga appeared in only one patient.     

斑点追踪成像技术对冠心病患者长轴节段性室壁运动异常的评价

目的 :探讨斑点追踪成像技术(speckle tracking imaging,STI)评价长轴左室节段性室壁运动异常的临床价值。方法 :采用STI技术检测41例健康人及29例冠心病患者心尖四腔切面、两腔切面及三腔切面18节段的STI纵向峰值应变(LS),并与冠状动脉造影异常供血室壁节段结果及M型超声心动图检测室壁运动结果比较。结果:冠心病患者左室壁运动异常节段STI表现为LS的明显降低,18节段LS均较对照组减低(P0.01);冠心病组M型超声心动图表现为室壁运动幅度减低或消失,室壁增厚率减低或消失,18节段室壁运动幅度均较对照组减低(P0.01)。STI对冠心病的阳性检出率为87.3%(269/308),M型超声心动图对冠心病的阳性检出率为63.3%(195/308),二者差异有统计学意义(P0.05)。结论:STI技术能够早期、无创、快速、客观地定量和定性分析左室壁节段性运动异常,明显提高节段性室壁运动异常的检出率。     

WB-DWI在恶性肿瘤淋巴结转移中的应用

目的:探讨磁共振全身弥散加权成像(whole body diffusion-weighted imaging,WB-DWI)在恶性肿瘤淋巴结转移瘤中的应用价值。方法:对110例疑似恶性肿瘤淋巴结转移患者行WB-DWI检查,并于扫描后1周内对可疑骨转移部位及原发恶性肿瘤部位行常规MRI/CT检查。根据MRI/CT及临床综合诊断结果,将所有患者分为淋巴结转移组及非淋巴结转移组,对资料进行统计学分析,比较单独应用WB-DWI、MRI/CT及二者联合应用(WB-DWI+MRI/CT)在恶性肿瘤淋巴结转移中的诊断价值。分别测定淋巴结转移组及非淋巴结转移组的ADC值,比较其在良恶性病变鉴别诊断中的价值。结果:①将淋巴结按长径大小分为<2cm,2～3cm,>3cm,WB-DWI、MRI/CT及WB-DWI+MRI/CT对长径<2cm淋巴结转移的检出差异具有统计学意义。进一步两两比较,单独应用MRI/CT与WB-DWI+MRI/CT的差异具有统计学意义(χ2=6.519,P=0.011)。②ROC分析结果显示,WB-DWI+MRI/CT诊断恶性肿瘤淋巴结转移的特异度、诊断准确性、阳性预测值及阴性预测值诊断最高。③淋巴结转移组ADC值明显低于良性淋巴结病变组,在良恶性淋巴结转移鉴别诊断中具有一定作用。结论:WB-DWI是常规MRI、CT的有益补充,与MRI/CT的联合应用可以提高恶性肿瘤淋巴结转移的诊断率,结合ADC值测定,在恶性肿瘤淋巴结转移诊断和鉴别方面具有一定价值。     

A general comparison of functional imaging in nuclear medicine with other modalities

New (noninvasive) diagnostic procedures in medicine (ultrasound [US], digital subtraction angiography [DSA], computed tomography [CT], nuclear magnetic resonance [NMR]) create a need for a review of the clinical utility of functional imaging in nuclear medicine. A general approach that is valid for all imaging procedures is not possible. For this reason, an individual assessment for each class of functional imaging is necessary, taking into account the complexity and sophistication of the various imaging procedures. This leads to a hierarchical order: first order functional imaging: imaging of organ motion (heart, lungs, blood); second order functional imaging: imaging of excretory function (kidneys, liver); and third and fourth order functional imaging: imaging of metabolism (except excretory function). First order functional imaging is possible fundamentally, although with limitations in detail, by all modalities. Second order functional imaging is not possible with US. Third and fourth order functional imaging is a privilege of nuclear medicine alone. Up to now, NMR has not proven clinically useful to produce metabolic images in its true sense. This is due to the fact that the signals used are too weak to provide metabolic information with satisfactory local resolution, even after administration of nonradioactive isotopes. First and second order functional imaging of nonradioactive procedures face severe disadvantages, including difficulties in performing stress investigations, which are essential for coronary heart disease, limited capability for true quantitative information (eg, kidney clearance in mL/min), side effects of contrast media and paramagnetic substances, and high costs. Therefore, nuclear medicine functional imaging turns out to be in a favorable clinical position, even in the presence of the competitive diagnostic modalities that have been developed in recent years.     

99Tcm-MIBI甲状腺显像鉴别甲状腺结节良恶性再认识

目的评价^99Tc^m-甲氧基异丁基异腈（MIBI）甲状腺亲肿瘤显像鉴别甲状腺结节良恶性的临床价值。方法106例甲状腺结节手术患者中101例先进行了甲状腺结节常^99Tc^mO4^-显像；106例患者均静脉注射^99Tc^m-MIBI 370 MBq后进行15min早期和2h延迟显像，结果与病理检查结果对比。结果13例甲状腺恶性肿瘤中的5例、93例良性结节中的23例^99Tc^m-MIBI显像阳性。^99Tc^m-MIBI显像诊断甲状腺恶性肿瘤的灵敏度为38．5％，特异性为75．3％，准确性为70．8％。甲状腺良恶性肿瘤显像的阳性率差异无显著性（x^2=0．49，P〉0．05）。结论^99Tc^m-MIBI显像不能鉴别甲状腺结节的良恶性，其临床意义有限。     

Magnetic resonance imaging of carotid artery abnormalities in patients with sphenoid sinusitis

Sphenoid sinusitis is unusual in children, but when it occurs, it can lead to serious intracranial complications. We show the value of MRI in demonstrating intracranial abnormalities due to sphenoid sinus infection, particularly those involving the internal carotid arteries and cavernous sinuses. We reviewed our imaging experience of sphenoid sinusitis and found four patients with ICA narrowing who had undergone MR evaluation including conventional and diffusion imaging. MR angiography was also performed in three patients to determine the extent of ICA narrowing. Narrowing of ICA was found in the cavernous segment in all patients and in the supraclinoid segment in three. Cerebral infarction was found in two patients. In one patient the cavernous sinus showed hyperintensity on diffusion-weighted images and hypointensity on apparent diffusion coefficient map, suggesting reduced diffusion. Although infrequent in children, sphenoid sinus infection should be considered as a possible cause of intracranial infection, particularly in teenagers. Early recognition of cavernous sinus involvement and ICA narrowing may lead to prompt treatment and hence a more favorable outcome.