Visual demonstration of aliasing in planar nuclear medicine imaging: The importance of correct collimator selection by nuclear medicine practitioners

Aliasing artefact is an imaging distortion phenomenon experienced in a wide variety of medical imaging modalities. This case report illustrates its occurrence during planar gamma camera nuclear medicine imaging under non-clinical conditions using experimental incorrect selection of collimators. In accordance with provision of an optimal service, nuclear medicine practitioners are recommended to have sufficient technical expertise along with knowledge of gamma camera operation. The purpose, construction and interaction of collimators used during planar imaging are presented herein with specific regards to the aliasing phenomenon. Furthermore, this case report recommends the careful planning of worklists to avoid frequent collimator changes to reduce the risk of human error.     

The effect of repeated strontium-89 chloride therapy on bone pain palliation in patients with skeletal cancer metastases

One hundred and eighteen patients with painful skeletal metastases of malignant diseases (predominantly prostate, breast and lung cancer) were treated with 150 MBq of strontium-89 chloride (Metastron, Amersham, UK) intravenously. The results were evaluated according to a score considering pain relief, mobility, analgesic intake and general feeling. In only five patients (4.2%) was no improvement observed; mild improvement was noted in 48 (40.7%), and substantial or complete improvement in 56 (47.5%) and 9 (7.6%), respectively. The mean painless period after a single ⁸⁹SrCl dose was 3.3±2.28 months (in patients with prostate, lung, breast and other types of cancer it was 3.65±2.11, 3.29±1.27, 3.08±0.48 and 3.44±1.36 months, respectively). During a 3-year study, ⁸⁹SrCl treatment was successively repeated up to 5 times in some patients (total number of Metastron applications was 256) who benefited from the first Metastron administration and did not show signs of myelosuppression. Even after repeated treatment, relief was consistent and the duration of the period without pain increased (in particular in patients with breast cancer, in whom the period of relief was prolonged from 3.08±0.48 months after the first dose to 5.33±2.36 months after the fifth ⁸⁹SrCl administration). The increased painless period was not observed after repeated treatment in the patient group comprising miscellaneous types of cancer, and the degree of improvement was less apparent. During the course of successive ⁸⁹SrCl treatments, transient signs of myelosuppression indicated by a decrease in white cell and thrombocyte counts of at least 25% were observed 10 times after Metastron administration (twice in two patients), i.e. in 3.9% of all ⁸⁹SrCl administrations; these transient haematological changes of moderate grade were closely connected with Metastron administration. Palliative treatment of metastatic skeletal pain with ⁸⁹SrCl improves the quality of life in most patients suffering from prostate, lung and breast cancer and may be safely repeated with the same benefit and without significant myelosuppression. The beneficial effect of ⁸⁹SrCl treatment seems to be less pronounced in other types of cancer with painful skeletal metastases. Received 9 February and in revised form 20 May 1998     

89Sr诱发K562癌细胞凋亡及其相关基因表达研究

目的 探讨^89Sr诱发K562癌细胞凋亡放射毒理效应的分子机理。方法 采用分子病理和定量病理技术研究^89Sr内照射诱导的K562癌细胞凋亡，剂量效应关系和重要相关基因bcl-和bax在其中的表达。结果 K562细胞经^89Sr内照射6和24h，提取DNA，琼脂糖凝胶电泳图谱上出现典型的“阶梯状”区带，伴有“拖尾”，而对照组未见“阶梯状”区带，荧光双标记流式细胞仪法定量检测，^89Sr内照射6，9，12，24和48h后，K562细胞凋亡率和坏死率均较对照组有明显升高（P＜0．01），随着^89Sr内照射时间的延长，累积剂量的提高，均无显著变化（P＞0．05），免疫组织化学染色显示，对照组K562细胞中bcl-2和bax蛋白均有表达，bcl-2蛋白表达阳性细胞率82．8％，bax为44.4%,bcl-2/bax比值1.86;^89Sr内照射24h后的K562细胞中，bcl-2蛋白表达阳性细胞率31.4%,bax为38.2%,bcl-2/bax比值0.82，与对照组相比，差异显著（P＜0．05）；RT－PCR显示bcl-2 mRNA在对照组K56细胞中高表达；^89Sr内照射12h后已有明显的下调，24h后则非常显著。结论 ^89Sr内照射K562细胞后，细胞凋亡与细胞坏死并存，且^89Sr诱导K5622细胞的凋亡可能是通过bcl-2 mRNA及其蛋白表达降低，bcl-2/bax比值下降而调控的。     

Estimation of deadtime in imaging human subjects

Deadtime count loss may cause significant errors in quantitative measurements performed by scintigraphic techniques. Deadtime depends on the scattering condition, and may vary among patients. The aim of this study was to estimate deadtime in imaging a human subject. A cylindrical phantom filled with various concentrations of technetium-99m solution was imaged with a gamma camera, and deadtime was assessed assuming the gamma camera to be a non-paralysable system (multi-dose method). Deadtime for the cylindrical phantom was also estimated using a point source to monitor counting efficiency (reference source method). Radionuclide angiography of the chest was performed in 38 patients with a reference source in the field of view, and temporal changes in count loss were assessed. The deadtime for each patient was calculated by the reference source method. The deadtime for the cylindrical phantom was estimated as 6.96±0.09 μs by the reference source method and was almost identical to that obtained by the multi-dose method (6.93 μs). Deadtime ranged from 6.01 to 9.58 μs in radionuclide angiography, and was positively correlated with the ratio of body weight in kg to body height in cm (y=8.566 x+5.611, r=0.869). Count loss was successfully corrected using the deadtime predicted with the regression line. In summary, the deadtime in imaging a human subject has a wide range and is related to the constitution of the subject. Correction for count loss using a deadtime predicted for each patient may be helpful in improving the reliability of quantitative nuclear medicine. Received 16 December and in revised form 28 April 1998     

Strontium-89 for palliation of pain from bone metastases in patients with prostate and breast cancer

We have used strontium-89 chloride (⁸⁹Sr) for the palliative treatment of metastatic bone pain. Seventy-six patients (50 males with prostate carcinoma and 26 females with breast cancer) were treated with 148 MBq of ⁸⁹Sr. Sixteen patients were retreated, receiving two or three doses; the total number of injected doses was consequently 95. The Karnofsky performance status was assessed and pain and analgesia were scored on scales of 9 and 5 points, respectively. The efficacy of ⁸⁹Sr was evaluated at 3 months of treament. Three levels of response were considered: good – when there was an increase in the Karnofsky status and a decrease in the pain score (equal to or higher than 4) or analgesic score (equal to or higher than 1); partial – when there was an increase in the Karnofsky status and a decrease in the pain score (2 or 3 points) without significant changes in the analgesic score; no response – if no variation or deterioration in these parameters was observed. In prostate cancer patients, the response was good in 64% of cases and partial in 25%, and there was no response in the remaining 11%. In breast cancer patients, the response was good in 62% of cases and partial in 31%, and there was no response in the remaining 8%. Duration of the response ranged from 3 to 12 months (mean 6 months). In the patients who were retreated the effectiveness was as good as after the first dose of ⁸⁹Sr. A decrease in the initial leucocyte and platelet counts was observed after the 1st month of treatment, with a gradual partial to complete recovery within 6 months. It is concluded that ⁸⁹Sr is an effective agent in palliative therapy for metastatic bone pain in patients with prostate or breast carcinoma. If required, retreatment can be administered safely and with the same efficacy as is achieved by the first dose. Received 13 March and in revised form 6 June 1997     

Motion detection and correction using multi-rotation 180° single-photon emission tomography for thallium myocardial imaging

Patient and organ motion is a potentially limiting factor in gamma camera single-photon emission tomography (SPET) imaging, as highlighted in stress thallium myocardial SPET, where the heart may exhibit a systematic axial motion (cardiac creep) following stress. Multi-rotation SPET has previously been described as a means of obtaining better raw data for motion detection and correction. This study describes the validation of a computerised motion detection algorithm applied to multi-rotation SPET, and reports measured motions in thallium myocardial stress SPET studies from a single-headed gamma camera. Forty-two patients underwent pharmacological stress (dipyridamole) with leg raising, with injection of 75 MBq thallium-201 and imaging after a 10-min delay to detect or evaluate coronary artery disease. Multi-rotation gamma camera SPET was performed with a single-headed gamma camera, with five sequential rapid (4.5 min) continuous SPET mode rotations over 180°. A one-dimensional cross-correlation alignment technique was applied to the projection images to perform motion detection and correction in the axial direction prior to combining the five data sets for tomographic reconstruction. Validation of the cross-correlation alignment analysis was carried out by performing imaging with measured whole-body axial motions in nine subjects, and by reproducibility measurements on multi-rotation data sets. The effect of the applied motion correction was evaluated by calculating mean differences between image pairs before and after shifting, and the general reliability of the automatic motion detection was checked to within one pixel by visual assessment of 160 image pairs. Validation measurements of the cross-correlation technique gave a mean absolute error of 1.5±0.4 mm (0.24±0.06pixels) with a maximum error of 3.7 mm (0.6 pixels). In 40 subjects undergoing pharmacological stress ²⁰¹Tl myocardial SPET imaging, the mean cardiac axial creep movement was calculated as 3.1±0.7 mm (0.49±0.11 pixels), with 13 out of 40 (32%) having a calculated motion of 1 pixel (6.3 mm) or more. The automatic image shift was visually judged to be within 1 pixel in all 160 image pair analyses, and the mean pixel value difference between image pairs was reduced following image shifting. It is concluded that multi-rotation 180° SPET imaging provides raw data which allow objective and accurate motion detection of cardiac motion in thallium stress myocardial imaging, whilst the one-dimensional cross-correlation technique demonstrates adequate accuracy and reliability to be applied as an automatic motion screening technique on these data. Received 14 March and in revised form 27 July 1998     

Optimization of collimators for imaging positron emitters by a gamma camera

The imaging of positron-emitting isotopes using a gamma camera requires special collimators. A ray-tracing method for simulating the point-spread function of collimators and, therefore, the total gamma camera system is presented. Simulated data obtained by this method showed good agreement with experimental data. Using this method, optimal lead and tungsten collimators for positron emitters were devised; at an object distance of B=100 mm, these yielded a pointspread function with an FWHM_tot=9.1 mm using an intrinsic resolution of FWHM_intr=8.0 mm.     

Longitudinal assessment of glomerular filtration rate by gamma camera and portable external detector

Noninvasive isotope chelate methods to assess glomerular filtration rate (GFR) are less accurate than blood sampling. However, some measurement errors would be expected to be constant for an individual, and repeat estimations may be less variable. In 18 patients, estimates of GFR were obtained by 2 gamma camera techniques and a portable external detector at a mean interval of 1 year, to assess accuracy in predicting a change of GFR. Errors in these techniques were not significantly better than those predicted from two independent estimates. Most GFR measurement error for noninvasive methods appears to be random.     

DWI在早期评价脑转移瘤伽玛刀疗效中的价值

目的 探讨磁共振扩散加权成像(DWI)在评估脑转移瘤伽玛刀治疗后早期疗效中的价值.方法 26例脑转移瘤患者,采用医科达公司Leksell Perfexion伽玛刀,周边剂量为14～21 Gy.所有患者在治疗前及治疗后1月均行常规MRI及DWI检查,并采用Functool 9.4.05a软件计算肿瘤体积、表观扩散系数(ADC)值及指数化表观扩散系数(eADC)值.结果 26个采用伽玛刀治疗的转移瘤病灶,其治疗前体积、ADC及eADC值分别为(5.685±4.582) cm3、(1.068±0.417)×10-3 mm2/s和0.377±0.128;而伽玛刀治疗后1月分别为(3.402±3.668) cm3、(1.355±0.472)×10-3mm2/s和0.286±0.103.采用配对样本t检验进行统计学分析发现,治疗前后体积(t=3.138,P=0.004)、ADC值(t=3.133,P=0.004)及eADC值(t=4.190,P=0.000)的变化均有显著统计学差异.结论 DWI可以早期反映脑转移瘤伽玛刀治疗后的变化,有助于转移瘤伽玛刀治疗后疗效的评估.     

The suitability of gamma camera coincidence systems for nitrogen 13-labeled ammonia myocardial perfusion imaging: A quantitative comparison with full-ring PET

BACKGROUND: The aim of this study was to examine the quality of nitrogen 13-labeled ammonia (NH(3)) perfusion data from coincidence-capable gamma camera positron emission tomography (GC-PET) systems compared with that from full-ring positron emission tomography (FR-PET). METHODS AND RESULTS: The performance parameters of the GC-PET system were examined and found adequate for imaging at the activity levels used clinically. We studied 15 patients who underwent stress and rest N-13-labeled NH(3) perfusion imaging on FR-PET and GC-PET systems. Quantitative analysis of perfusion values showed that GC-PET uptake was significantly lower than FR-PET uptake in 67.6% of segments. Bland-Altman analysis showed that the mean difference between FR-PET and GC-PET values was from 5.3% to 5.9%. Stress FR-PET identified 49 segments as having impaired perfusion, 46 (93.9%) of which were also identified by GC-PET. Fifty-six additional segments were identified as abnormal by GC-PET. These findings indicated a general overestimation of defect size on GC-PET. Analysis of the degree of perfusion reduction also found that GC-PET tended to overestimate defect contrast. These findings are similar to those previously found by workers examining fluorine 18-fluorodeoxyglucose uptake by both techniques. CONCLUSIONS: Good concordance was shown between GC-PET and FR-PET systems for N-13-labeled NH(3) perfusion imaging, although further work is required to optimize the technique.     

Early detection of melanoma metastases with radioiodinated methylene blue

Melanin synthesised in melanoma cells presents a unique target to which the treatment can be selectively addressed, provided the pigment is recognised by a suitable drug. Methylene blue (MTB) possesses a high affinity for melanin and, therefore, accumulates preferentially in melanoma cells. Since not directly toxic to the tumour, MTB serves as a carrier for radioisotopes and, once taken up by melanoma cells, acts as a selectively localised source of radiation. Hence, radioderivatives of the compound can be used for both diagnosis and therapy of disseminated melanoma. Eleven patients with confirmed metastatic melanoma and one with a recent local recurrence were studied using radioiodinated (iodine-123 or iodine-131) MTB and a gamma camera. Biopsies of cutaneous lesions were taken to determine directly the compound uptake in tumours. This first clinical investigation concerning the diagnostic potential of radioiodinated MTB in patients with disseminated melanoma confirmed the existence of approximately 80% of internal lesions previously identified by routine methods and, additionally, enabled detection of unknown secondaries in 6 of 12 patients studied. There were no false-positive gamma camera images regardless of whether ¹²³I or ¹³¹I was used. ¹³¹I proved to be more suitable than ¹²³I for detecting melanoma metastases with radioiodinated MTB. Hazy images of the lesions treated with external beam radiation and/or some drugs suggest that initial radio- and chemotherapy might affect MTB uptake in melanoma metastases and reduce the clarity of the scintigrams obtained from a gamma camera. However, small, untreated internal lesions that cannot be visualised easily with the standard diagnostic methods are revealed with ¹³¹I-MTB regardless of their localisation. It is concluded that use of radioiodinated MTB in conjunction with gamma camera or positron emission tomographic imaging might prove to be a useful and accessible tool for the detection of early melanoma dissemination. Received 12 May and in revised form 3 June 1998     

Detection and localization of carcinoma within the prostate using high resolution transrectal gamma imaging (TRGI) of monoclonal antibody directed at prostate specific membrane antigen (PSMA)—Proof of concept and initial imaging results

Purpose

Molecular imaging methods may identify primary prostate cancer foci and potentially guide biopsy and optimal management approaches. In this exploratory study, safety and first human imaging experience of a novel solid state endocavity transrectal gamma-imaging (TRGI) device was evaluated.

Methods

Twelve patients received 5 ± 0.5 mCi In-111 capromab pendetide (ProstaScint^®) intravenously and the prostate of each was imaged 4 days later transrectally using an endoluminal cadmium zinc telluride (CZT)-based compact gamma camera (ProxiScan™, Hybridyne Imaging Technologies, Inc.). Immediate and 5–7-day post imaging safety assessments were performed. In those patients with a prostate cancer diagnosis (N = 10), single photon emission computed tomography (SPECT-CT) and magnetic resonance imaging (MRI) of the pelvis were also acquired. Images were reviewed and sites of suspected cancer were localized by prostate quadrant by consensus of two nuclear medicine physicians. Pathology from TRUS biopsy, or surgical pathology following prostatectomy (N = 3) when available, served as the gold standard.

Results

There were no serious adverse events associated with TRGI. No focal signal was detected in patients without a diagnosis of prostate cancer (N = 2). Of 40 quadrants evaluated in the cancer cohort (N = 10), 22 contained malignancy. In 8 of these 10 patients, the most focal site of uptake on TRGI corresponded to a prostatic quadrant with biopsy-proven malignancy. In 6 cancer-containing quadrants, TRGI was positive where SPECT-CT was negative; MRI showed a detectable abnormality in only 1 of these 6 quadrants. Qualitative image review of the planar TRGI images for prostate cancer localization was severely limited in some cases by scatter artifact within the vicinity of the prostate gland arising from physiologic urine and blood pool activity from nearby structures.

Conclusions

TRGI is a safe imaging method that can potentially detect radiopharmaceutical uptake of primary prostate cancer and facilitate prostatic quadrant – localization of cancer. Further investigation of this technology is warranted.     

MRI对伽玛刀治疗脑转移瘤及瘤周水肿疗效的分析

目的MRI评估伽玛刀治疗前后脑转移瘤及瘤周水肿的改变。方法选取42例[男28例,女14例,平均年龄（59．8±12．3）岁]共75个病灶,分别于伽玛刀治疗前1天和治疗后3个月行增强MRI检查,通过计算肿瘤体积和水肿指数的改变来评价伽玛刀疗效。结果MRI显示治疗前肿瘤平均体积为7．0cm3,治疗后减小为3．3cm3;水肿指数由治疗前的9．9减小为4．3。局部肿瘤和水肿控制率分别达到90．7％和85．0％。结论伽玛刀对转移瘤及瘤周水肿有较高控制率,而且肿瘤体积影响伽玛刀疗效。     

Quantitative PET imaging of Met-expressing human cancer xenografts with <Superscript>89</Superscript>Zr-labelled monoclonal antibody DN30

Purpose  Targeting the c-Met receptor with monoclonal antibodies (MAbs) is an appealing approach for cancer diagnosis and treatment because this receptor plays a prominent role in tumour invasion and metastasis. Positron emission tomography (PET) might be a powerful tool for guidance of therapy with anti-Met MAbs like the recently described MAb DN30 because it allows accurate quantitative imaging of tumour targeting (immuno-PET). We considered the potential of PET with either ⁸⁹Zr-labelled (residualising radionuclide) or ¹²⁴I-labelled (non-residualising radionuclide) DN30 for imaging of Met-expressing tumours. Materials and methods  The biodistribution of co-injected ⁸⁹Zr-DN30 and iodine-labelled DN30 was compared in nude mice bearing either the human gastric cancer line GLT-16 (high Met expression) or the head-and-neck cancer line FaDu (low Met expression). PET images were acquired in both xenograft models up to 4 days post-injection (p.i.) and used for quantification of tumour uptake. Results  Biodistribution studies in GTL-16-tumour-bearing mice revealed that ⁸⁹Zr-DN30 achieved much higher tumour uptake levels than iodine-labelled DN30 (e.g. 19.6%ID/g vs 5.3%ID/g, 5 days p.i.), while blood levels were similar, indicating internalisation of DN30. Therefore, ⁸⁹Zr-DN30 was selected for PET imaging of GLT-16-bearing mice. Tumours as small as 11 mg were readily visualised with immuno-PET. A distinctive lower ⁸⁹Zr uptake was observed in FaDu compared to GTL-16 xenografts (e.g. 7.8%ID/g vs 18.1%ID/g, 3 days p.i.). Nevertheless, FaDu xenografts were also clearly visualised with ⁸⁹Zr-DN30 immuno-PET. An excellent correlation was found between PET-image-derived ⁸⁹Zr tumour uptake and ex-vivo-assessed ⁸⁹Zr tumour uptake (R ² = 0.98). Conclusions  The long-lived positron emitter ⁸⁹Zr seems attractive for PET-guided development of therapeutic anti-c-Met MAbs.     

乳腺专用γ显像的图像特征对乳腺病变的鉴别诊断价值

目的探讨乳腺专用γ显像（BSGI）的图像特征对乳腺病变的鉴别诊断价值。方法回顾性分析2014年7月至2015年6月行BSGI的272例中国女性乳腺疾病患者（共293个病灶）,观察BSGI图像上病灶形态、病灶边缘是否清晰、灰度分布是否存在“偏心核心”、乳腺影像报告和数据系统（BIRADS）结果以及最大肿瘤/非肿瘤比值（T/NT）。采用二变量秩相关分析及二分类Logistic回归分析法计算上述特征与病理结果的相关性。基于病灶计算所有图像特征的独立诊断效能以及上述显著相关特征的合并诊断效能,用MedCalc软件行Z检验比较上述特征的受试者工作特征曲线。结果病灶形态（OR=0.013,95%CI：3.664~21.846,P=0.000）、病灶边缘是否清晰（OR=2.121,95%CI：1.061~4.239,P=0.033）以及灰度分布是否存在“偏心核心”（OR=12.927,95%CI：5.415~30.863,P=0.000）与病理结果显著相关。三者的灵敏度、特异度分别为92.0%（172/187）和58.5%（62/106）、66.8%（125/187）和71.7%（76/106）、95.7%（179/187）和27.4%（29/106）。三者合并诊断效能最佳,灵敏度、特异度、阳性预测值、阴性预测值、准确率分别为88.2%（165/187）、81.1%（86/106）、89.2%（165/185）、79.6%（86/108）和85.7%（251/293）,较BIRADS以及最大T/NT（界值：1.75）更准确,且差异均有统计学意义（Z=4.079、4.090,均P<0.05）。结论病灶形态、病灶边缘是否清晰以及灰度分布是否存在“偏心核心”可作为BSGI鉴别诊断乳腺病灶的图像特征,三者联合诊断能提高BSGI在乳腺病变中的独立诊断价值。     

Differential diagnosis between metastatic tumors and nonsolid benign lesions of the liver using ferucarbotran-enhanced MR imaging

Purpose

To evaluate ability of ferucarbotran-enhanced MR imaging (MRI) in differentiating metastases from nonsolid benign lesions of the liver according to signal-intensity characteristics.

Materials and methods

Sixty-six consecutive patients, who had 138 focal hepatic lesions (26 cysts, 11 hemangiomas, and 101 metastases), underwent ferucarbotran-enhanced MRI. The signal-intensity pattern of each kind of lesion relative to the liver parenchyma on ferucarbotran-enhanced T2* and heavily T1-weighted gradient-echo images were assessed and categorized into the following three categories: high-intensity and iso-intensity, respectively (category A), high and low (category B), and iso- and low-intensity (category C). For category B, lesions were subdivided into two groups based on single-shot half-Fourier RARE images: category B1 (not significantly high-intensity) and category B2 (significantly high-intensity).

Results

Category A had 11 hemangiomas and 2 metastatic tumors, category B1 had 97 metastatic tumors, category B2 had 2 metastatic tumors and 9 cysts, and category C had 17 cysts. When a tumor with a signal intensity of category A was considered to be hemangioma, category B1 metastasis, and category B2 and C cyst, the diagnostic accuracy for differentiating these lesions was 97% (134/138).

Conclusion

The combination of signal-intensity pattern on ferucarbotran-enhanced T2*- and heavily T1-weighted gradient-echo MRI has ability to differentiate liver metastases from nonsolid benign lesions. However, T2-weighted single-shot half-Fourier RARE imaging should also be employed to achieve better performance.     

Iron deposition in multiple sclerosis lesions measured by susceptibility-weighted imaging filtered phase: a case control study

Purpose:

To investigate phase lesions identified on susceptibility‐weighted imaging (SWI)‐filtered phase images in patients with multiple sclerosis (MS), clinically isolated syndrome (CIS) and healthy controls (HC). To relate phase lesion characteristics to other clinical and MRI outcomes.

Materials and Methods:

95 relapsing‐remitting (RR), 40 secondary‐progressive (SP) MS patients, as well as 19 CIS patients and 49 age‐ and sex‐matched HC, were scanned on a 3T scanner. Phase‐, T1‐, and T2‐lesion characteristics were determined. Overlap of T1‐ and T2‐weigthed imaging (WI) lesions with phase lesions (T1P and T2P), as well as brain atrophy outcomes, was assessed.

Results:

MS patients showed significantly greater numbers and larger volume of phase lesions, compared with HC (P < 0.001). 23.6% of T2 lesions overlapped with phase lesions, whereas the same figure for T1 lesions was 37.3%. Conversely, 33.4% and 69.7% of phase lesions were not visible on T2‐ or T1‐WI, respectively. Phase, T1P and T2P lesions were not related to clinical outcomes, but phase lesions were related to ventricular enlargement.

Conclusion:

Phase lesions were present in both MS and CIS patients, and showed partial overlap with lesions observed using conventional MRI. The role of phase lesions in clinical progression remains unclear and should be further explored. J. Magn. Reson. Imaging 2012;36:73–83. © 2012 Wiley Periodicals, Inc.     

New concepts in understanding evolution of desmoid tumors: MR imaging of 30 lesions

The objective of this study was to evaluate the appearance and the natural evolution of desmoid tumors on MR imaging, given histologic correlation. The MR images of 30 desmoids (20 primary and 10 recurrent) in 26 patients were scored for a multiplicity of morphological parameters, signal intensity (SI) on different pulse sequences, and behavior after contrast administration. Natural evolution was evaluated in 2 primary and 3 recurrent lesions, and correlated with evolution on histologic specimens. Desmoid tumors are mostly found in muscles of shoulder and hip girdle and are often fusiform with partially ill-defined margins. Rare subcutaneous desmoids have a more stellar morphology. Variable amounts of low-SI areas are present on all sequences. On T1-weighted images (T1-WI), most lesions are near homogeneous and isointense to muscle, whereas on T2-WI they are more heterogeneous with an overall SI equal to or slightly lower than fat. Histologic correlation reveals that SI on T2-WI cannot be explained solely by cellularity. After initial growth, spontaneous evolution of desmoids is characterized by shrinking and an increase in low-SI areas on T2-WI. While distal lesions shrink, the more recent lesions in asynchronous multicentric desmoids have a tendency to develop proximally in the same limb, and should not be confused with recurrences. Fast growth, extracompartmental spread, and bone involvement are often seen in recurrences. Follow-up MR imaging of desmoids indicates natural regression of desmoids and more aggressive behavior of recurrences, which may justify a more conservative therapeutic approach. Received 30 July 1996; Revision received 26 November 1996; Accepted 16 January 1997     

Benign versus malignant osseous lesions in the lumbar vertebrae: differentiation by means of bone SPET

Bone scanning is a well-accepted and frequently performed diagnostic procedure with a high sensitivity, especially when single-photon emission tomography (SPET) acquisitions are added. However, the differentiation of benign from malignant osseous lesions often poses difficulty. The purpose of this study was to find out whether the particular localisation of an intraosseous lesion in a lumbar vertebra is an indicator of its aetiology. Bone scintigraphy including planar whole-body scans as well as SPET imaging of the lumbar spine was performed in 109 patients. The diagnoses of osseous lesions in the lumbar vertebrae were made strictly on the basis of the findings of magnetic resonance imaging, computed tomography or plain radiography. Sixteen patients had to be excluded from the study because they did not undergo adequate radiological examination. To determine the particular localisation of vertebral lesions in the bone scan, two experienced nuclear medicine physicians examined the studies independently while blinded to the radiological results. Four anatomical regions were differentiated within the vertebra: the vertebral body, the pedicle, the facet joints and the spinous process. Clopper-Pearson analysis, which takes into account the number of examinations, yielded the following probability intervals for the malignancy of intraosseous lesions in the lumbar spine: vertebral body 36.8%–57.3%, pedicle 87.7%– 100%, facet joints 0.8%–21.4% and spinous process 18.7%–81.3%. It was concluded that lesions affecting the pedicle are a strong indicator for malignancy, whereas involvement of the facet joints is usually related to benign disease. Lesions affecting the vertebral body or the spinous process do not show a clear tendency towards either malignancy or benignity. In contrast to other studies, a significant probability of malignancy (35.6%) was observed in lesions affecting exclusively the vertebral body. Received 23 November 1999 and in revised form 12 February 2000     

Evaluation of patellar cartilage surface lesions: comparison of CT arthrography and fat-suppressed FLASH 3D MR imaging

The aim of this study was to evaluate the sensitivity and specificity of fat-suppressed fast low-angle shot (FLASH) 3D MR imaging in the detection of patellar cartilage surface lesions in comparison with CT arthrography. Fifty patients, with or without symptoms of chondromalacia, were prospectively examined by CT arthrography and fat-suppressed 3D gradient-echo MR imaging. All MR examinations were evaluated by three observers, two of them reaching a consensus interpretation. The lesions were graded according to their morphology and their extent. The CT arthrography was considered as the reference examination. For both sets of observers, the final diagnosis of chondromalacia was obtained in 92.5 %. The specificity was 60 % on a patient-by-patient basis. Fissures were missed in 83 and 60 %, respectively, but were isolated findings only in 2.5 % of the cases. Considering ulcers involving more than 50 % of the cartilage thickness, 65 and 88 %, respectively, were recognized. Fat-suppressed FLASH 3D is an adequate pulse sequence for the detection of patellar cartilage ulcers. It can be applied on a routine clinical basis, but it does not show as many fissures as CT arthrography and is less precise for grading of lesions. Received 30 July 1997; Revision received 23 December 1997; Accepted 29 December 1997