The role of SPECT-CT in the lymphoscintigraphic identification of sentinel nodes in patients with oral cancer

Conclusion: SPECT-CT may improve the localization of sentinel nodes (SNs) in patients with oral squamous cell carcinoma (OSCC). Compared with planar lymphoscintigraphy SPECT-CT detected more SNs and provided additional anatomical and spatial information about their localization. New generation SPECT with higher resolution CT scanners are expected to provide more accurate information about the localization of SNs. Objective: To assess the role of combined SPECT-CT in SN identification in the clinically negative neck of patients with OSCC. Materials and methods: Lymphoscintigraphy comprising planar and SPECT-CT acquisition was performed in 34 consecutive patients with OSCC stage I and II (T1-2N0M0) prior to sentinel node biopsy (SNB) and selective neck dissection. The number of SNs and anatomical location was recorded according to lymphoscintigraphy and operative findings. Results: SNB was conducted in 33 patients. SNs were identified in 94% (32/34) of the patients using SPECT-CT. In 91% (29/32) of the patients SNs were harvested from all of the levels involved on SPECT-CT. SPECT-CT imaging demonstrated extra SNs compared with planar lymphoscintigraphic imaging in 47% (15/32) of patients. In seven cases the anatomical level of SN according to SPECT-CT was reclassified during surgery. The overall incidence of lymph node metastases was 19% (6/32). There were no false negative SNs.     

Posttherapeutic <Superscript>131</Superscript>I SPECT-CT offers high diagnostic accuracy when the findings on conventional planar imaging are inconclusive and allows a tailored patient treatment regimen

Purpose  The purpose of this prospective study was to determine the diagnostic impact and influence on patient treatment of posttherapeutic ¹³¹I SPECT-CT when the findings on planar posttherapeutic whole-body scintigraphy (ptWBS) were inconclusive. Materials and methods  A total of 53 SPECT-CT scans were performed in 41 patients with thyroid cancer after high-dose ¹³¹I therapy (2.944 to 7.526 GBq ¹³¹I) because of diagnostic uncertainty on ptWBS. Physiological uptake in the salivary glands, gastric mucosa, gut, nasal mucosa, urinary tract and liver were considered to be normal. Any other foci of increased ¹³¹I uptake, except iodine uptake clearly located in the thyroid bed, were considered to be abnormal. The data were evaluated on a lesion and a patient basis. Results  Regarding neck lesions, SPECT-CT provided a diagnostic impact in 26/90 lesions (28.9%) and confirmed the diagnosis in 64/90 lesions (71.1%). On a patient basis, SPECT-CT changed N status in 12/33 patients (36.4%), provided a diagnostic impact in 21/33 patients (63.6%) and led to a treatment change in 8/33 patients (24.2%). Regarding lesions distant from the neck, SPECT-CT confirmed the diagnosis in 62/71 lesions (87.3%) and had a diagnostic impact in 9/71 lesions (12.7%). On a patient basis, SPECT-CT changed M status in 4/19 patients (21.1%), had a diagnostic impact in 14/19 patients (73.7%) and led to a treatment change in 2/19 patients (10.5%). Considering all patients, SPECT-CT led to a treatment change in 10/41 patients (24.4%). Conclusion  Integrated SPECT-CT is a useful tool, especially in cases of diagnostic uncertainty and helps to individualize patient management.     

Myeloperoxidase Activity Imaging Using <Superscript>67</Superscript>Ga Labeled Substrate

Purpose The aim of the study is to assess the feasibility of imaging specific activity of myeloperoxidase (MPO), a leukocyte enzyme with important roles in inflammation and atherosclerosis, by single photon emission computed tomography (SPECT) using a novel ⁶⁷Ga-labeled radiotracer obtained by conjugating desferrioxamine (DF) and hydroxyindolyl acetic acid in vivo. Materials and Methods A reducing substrate of MPO (I) was synthesized by reacting commercially available DF with 2-(5-hydroxy-1H-indol-3-yl) acetic acid in the presence of a coupling agent [dicyclohexyl carbodiimide (DCC)]. The chelating unit was labeled with ⁶⁷Ga, and its interaction with MPO was characterized using MALDI-TOF and UV–vis. Mice with Matrigel implants containing human MPO were used to model diseased tissues rich in MPO. Three hours after the injection of ⁶⁷Ga–I, SPECT/computed tomography (CT) imaging was performed on a high-resolution Gamma Medica X-SPECT system. Biodistribution studies were performed six hours after the injection of the radiotracer. Results The feasibility of compound I oligomerization in the presence of MPO and MPO-mediated cross-linking with proteins was initially confirmed in vitro. In vivo, a 2.7-fold increase in target-to-muscle ratio could be measured in MPO-containing Matrigel implants in mice. Biodistribution experiments demonstrated a 60% increase of radioactivity in MPO-containing vs. control (contralateral) Matrigel implants. Conclusion ⁶⁷Ga–I can be used to image MPO activity in a model system. The accumulation mechanism is based on a differential pharmacokinetics because of the size increase resulting from ⁶⁷Ga–I interaction with the target enzyme. M. Querol and J. W. Chen contributed equally to this work.     

Use of coronary calcium score scans from stand-alone multislice computed tomography for attenuation correction of myocardial perfusion SPECT

Purpose To evaluate the use of CT attenuation maps, generated from coronary calcium scoring (CCS) scans at in- and expiration with a 64-slice CT scanner, for attenuation correction (AC) of myocardial perfusion SPECT images. Methods Thirty-two consecutive patients underwent ^99mTc-tetrofosmin gated adenosine stress/rest SPECT scan on an Infinia Hawkeye SPECT-CT device (GE Medical Systems) followed by CCS and CT angiography on a 64-slice CT. AC of the iteratively reconstructed images was performed with AC maps obtained: (a) from the “Hawkeye” low-resolution X-ray CT facility attached to the Infinia camera (IRAC); (b) from the CCS scan acquired on a 64-slice CT scanner during maximal inspiration (AC_INSP) and (c) during normal expiration (AC_EXP). Automatically determined uptake values of stress scans (QPS, Cedars Medical Sinai) from AC_INSP and AC_EXP were compared with IRAC. Agatston score (AS) values using AC_INSPversus AC_EXP were also compared. Results AC_INSP and AC_EXP resulted in identical findings versus IRAC by visual analysis. A good correlation for uptake values between IRAC and AC_INSP was found (apex, r=0.92; anterior, r=0.85; septal, r=0.91; lateral, r=0.86; inferior, r=0.90; all p<0.0001). The correlation was even closer between IRAC and AC_EXP (apex, r=0.97; anterior, r=0.91; septal, r=0.94; lateral, r=0.92; inferior, r=0.97; all p<0.0001). The mean AS during inspiration (319±737) and expiration(317±778) was comparable (p=NS). Conclusion Attenuation maps from CCS allow accurate AC of SPECT MPI images. AC_EXP proved superior to AC_INSP, suggesting that in hybrid scans CCS may be performed during normal expiration to allow its additional use for AC of SPECT MPI.     

Preserving functional lung using perfusion imaging and intensity-modulated radiation therapy for advanced-stage non-small cell lung cancer

PURPOSE: To assess quantitatively the impact of incorporating functional lung imaging into intensity-modulated radiation therapy planning for locally advanced non-small cell lung cancer (NSCLC). METHODS AND MATERIALS: Sixteen patients with advanced-stage NSCLC who underwent radiotherapy were included in this study. Before radiotherapy, each patient underwent lung perfusion imaging with single-photon-emission computed tomography and X-ray computed tomography (SPECT-CT). The SPECT-CT was registered with simulation CT and was used to segment the 50- and 90-percentile hyperperfusion lung (F50 lung and F90 lung). Two IMRT plans were designed and compared in each patient: an anatomic plan using simulation CT alone and a functional plan using SPECT-CT in addition to the simulation CT. Dosimetric parameters of the two types of plans were compared in terms of tumor coverage and avoidance of normal tissues. RESULTS: In incorporating perfusion information in IMRT planning, the median reductions in the mean doses to the F50 and F90 lung in the functional plan were 2.2 and 4.2 Gy, respectively, compared with those in the anatomic plans. The median reductions in the percentage of volume irradiated with >5 Gy, >10 Gy, and >20 Gy in the functional plans were 7.1%, 6.0%, and 5.1%, respectively, for F50 lung, and 11.7%, 12.0%, and 6.8%, respectively, for F90 lung. A greater degree of sparing of the functional lung was achieved for patients with large perfusion defects compared with those with relatively uniform perfusion distribution. CONCLUSION: Function-guided IMRT planning appears to be effective in preserving functional lung in locally advanced-stage NSCLC patients.     

SPECT-CT融合图像评价乳腺癌骨转移的增益价值

目的：探讨SPECT-CT融合图像评价乳腺癌骨转移的增益价值.方法：回顾分析经病理证实为乳腺癌、排除其他恶性肿瘤病史且行全身骨显像（whole-body bone scintigraphy,WBBS）及局部SPECT-CT（single photon emission computed tomograpby-computed tomography）融合图像检查的53例女性患者的临床资料,根据患者综合表现诊断为肿瘤骨转移、无肿瘤骨转移和不能确定,以手术病理或随访结果为最终诊断标准.分别计算并比较WBBS、SPECT-CT融合图像对病例及病灶诊断的灵敏度、特异度、阳性预测值、阴性预测值、正确诊断百分率、肿瘤骨转移诊断符合率和无肿瘤骨转移诊断符合率.结果：53例患者中确诊为肿瘤骨转移者27例,无肿瘤骨转移者26例;在共计177个病灶中,95个病灶确诊为肿瘤骨转移,82个病灶确诊为无肿瘤骨转移.WBBS对病例和病灶诊断的灵敏度、特异度、阳性预测值、阴性预测值分别为92.6％和93.7％、61.5％和73.2％、71.4％和80.2％、88.9％和90.9％;正确诊断百分率、肿瘤骨转移诊断符合率、无肿瘤骨转移诊断符合率分别为56.6％（30/53）和72.1％（111/177）、51.9％（14/27）和61.1％（58/95）、61.5％（16/26）和73.2％（60/82）.SPECT-CT融合图像对病例和病灶诊断的灵敏度、特异度、阳性预测值、阴性预测值分别为96.3％和98.9％、84.0％和95.1％、86.7％和95.9％、95.7％和98.7％;正确诊断百分率、肿瘤骨转移诊断符合率、无肿瘤骨转移诊断符合率分别为90.6％（48/53）和97.2％（172/177）、96.3％（26/27）和98.9％（94/95）、88.5％（23/26）和95.1％（78/82）,均高于WBBS（病例分析：x2分别为15.725、13.886和5.026,P值分别为0.000、0.000和0.025;病灶分析：x2分别为55.618、42.632和14.809,P值均为0.000）.结论：评价乳腺癌骨转移时,SPECT-CT融合图像较WBBS更具有增益价值.     

Sentinel node biopsy for oral and laryngopharyngeal squamous cell carcinoma: a retrospective study of 177 patients in Japan

Objective

Sentinel node (SN) biopsy in the head and neck region has not been widely used in Japan, except at a few facilities. However, almost all these facilities perform preoperative localization and intraoperative diagnosis by frozen section analysis of SN to select patients who must undergo neck dissection in a one-stage procedure. The objective of this study was to determine the actual status of SN biopsy at those facilities in Japan that have actively conducted this procedure, and to elucidate the usefulness and drawbacks of this technique in head and neck cancer.

Methods

We retrospectively reviewed 177 patients who had undergone SN biopsy at 7 facilities. The underlying pathology was laryngeal or hypopharyngeal cancer in 20 patients from one hospital, while the remaining 157 patients had oral cancer. Preoperative localization of SN was determined using conventional lymphoscintigraphy with or without single photon emission computed tomography with CT (SPECT-CT). Intraoperative localization and diagnosis of SN were performed by gamma probe and frozen section analysis.

Results

Conventional lymphoscintigraphy detected a mean of 2.6 SNs per patient in 137 patients with oral cancer, compared to 2.7 in 71 patients using SPECT-CT and 2.9 in 154 patients using the gamma probe. No significant differences were apparent between techniques. Forty of the 520 SNs (7.7%; 33 in oral cancer and 7 in laryngeal or hypopharyngeal cancer) were pathologically positive in the final diagnosis. Of these, 3 were not processed for frozen sectioning and were diagnosed only with hematoxylin and eosin staining. Among the others, 32 (86.5%) were diagnosed intraoperatively as showing metastasis. In terms of the false-negative rate, 144 patients were determined by SN biopsy to have no positive SNs. Of these, 2 patients had non-SN metastases found in their dissected neck and 8 patients without neck dissection showed late nodal recurrence. The false-negative rate was thus 6.9%.

Conclusion

Frozen section analysis, particularly multislice sectioning, offers a relatively reliable intraoperative diagnostic method. We were able to perform immediate neck dissection based on the results of multislice sectioning as a single-stage procedure.     

cN0喉癌前哨淋巴结的检测及意义

目的 应用核素法、染料法以及二者联合法检测cN0喉癌患者前哨淋巴结(SLN),并评价SLN对颈部淋巴结转移状况的预测价值.方法 41例cN0喉癌患者采用核素法、染料法和联合法示踪SLN.核素法为手术前于喉镜引导下在肿瘤周围注射99TCm-硫胶体(SC)进行SLN显像,手术中用γ探针探测放射性"热点";染料法为手术中注射亚甲蓝,示踪蓝染的SIN;联合法为将核素法和染料法联合应用的方法.结果 核素法、染料法和联合法对SLN的检出率分别为87.8%、70.7%和92.7%(P<0.01);核素法与联合法、染料法与联合法检出SIN数目的 差异有统计学意义(P<0.05,P<0.01),核素法与染料法检出SLN数目的 差异无统计学意义(P>0.05).病理结果示,有9例患者淋巴结转移,占22.0%.联合法检测SLN的灵敏度、准确度和阴性预测值分别为88.9%、97.4%和96.7%.结论 联合应用核素法和染料法可提高SEN检出的准确性,SLN的病理结果可以准确预测cN0喉癌患者颈部淋巴结的病理状态.     

Updates in postoperative imaging modalities following musculoskeletal surgery

Postoperative imaging following orthopaedic surgeries is essential in assessing complications post-surgery and also helps plan further treatment. Combining a high degree of clinical insight with appropriate imaging can guide the treating clinician to the correct diagnosis. Imaging is quite challenging because of surgery-related soft tissue changes, especially in the early postoperative period and the presence of metal implants resulting in image scatter and metal artifacts. Newer modalities and advances in imaging have helped overcome shortcomings and assess better, especially in procedures that involve implants. Collaborative decision-making involving radiologists and clinicians has shown to be beneficial and is the way forward. This narrative review discusses the utility of imaging in evaluating postoperative complications following musculoskeletal surgeries with specific relation to trauma, arthroplasty, and tumour by discussing commonly encountered clinical scenarios.