Single-photon Emission Computed Tomography CT Research Articles

The Role of Echocardiography in the Diagnosis of Infective Endocarditis and its Complications

Infective endocarditis (IE) remains associated with high morbidity and mortality rates despite advances in medical technology, diagnostics, and treatment. Hospital mortality for IE reaches up to 22%, with a five-year mortality rate of 40%. Globally, the incidence of IE has increased, with recent figures indicating 13.8 cases per 100,000 annually, up from 1.5–11.6 per 100,000 reported between 1990 and 2010. A retrospective cohort study in a tertiary care center in Korea demonstrated a significant rise in the monthly incidence of IE from 2.0 in 2005 to 3.8 in 2017. This increase is attributed to the enhanced utilization of diagnostic tools such as echocardiography, computed tomography (CT), and positron emission tomography (PET). The 2015 European Society of Cardiology (ESC) guidelines incorporated complementary imaging modalities like Single Photon Emission Computed Tomography-CT (SPECT/CT), 18F-FDG PET/CT, and Cardiac CT, alongside traditional transthoracic and transesophageal echocardiography. The 2023 ESC guidelines further expanded these algorithms to include Cardiac CTA, MRI, PET/CT, and WBC SPECT. However, transthoracic, and transesophageal echocardiography remain the primary and essential diagnostic tools for suspected IE. This review examines the role of echocardiography in diagnosing IE, highlighting typical ultrasound findings, valve damage, and associated complications. Ultrasound is pivotal for early detection and prognosis of IE, identifying vegetations, abscesses, pseudoaneurysms, and fistulas. New vegetations typically appear irregular and oscillate, with transthoracic echocardiography detecting vegetations larger than 5mm with 90% sensitivity. Detailed echocardiographic assessment provides critical insights for the surgical management of IE and enhances the understanding of IE’s complex pathology.

Preoperative identification of small parathyroid adenomas-better done by fluorocholine positron emission tomography/computed tomography.

Preoperative localization imaging studies are crucial for safe and successful parathyroidectomy in patients with primary hyperparathyroidism (pHPT), especially in focused approaches. A common imaging sequence is ultrasound followed by scintigraphy. These techniques, but not 18F-fluorocholine positron emission tomography/computed tomography (PET/CT), show lower detection rates in multiglandular disease (MGD), which is associated with smaller adenomas. In this study, we evaluate the accuracy of these modalities in small parathyroid adenomas (PAs) and discuss the potential sequence of preoperative localization diagnostics. Patients undergoing parathyroidectomy for pHPT were retrospectively categorized into small adenoma (specimen diameter <10 mm) and large adenoma. The groups were compared for accuracy of preoperative imaging studies, short-term and long-term outcomes. Among 147 patients retrospectively analyzed in this study, 38 small PAs were found. Preoperative correct quadrant prediction for small adenomas was significantly lower for ultrasound (P=0.03) and single-photon emission computed tomography/CT (SPECT/CT) (P<0.01) but not for choline PET/CT. While PET/CT was performed significantly more often in small PAs (P<0.01), it showed highly significant superiority over the other imaging modalities in accurate preoperative localization in both small (P<0.0001) and large PAs (P<0.01). There was no difference in calcium and parathyroid hormone (PTH) levels at latest follow-up with slightly more recurrences in small adenomas (P=0.08). Choline PET/CT showed a better diagnostic yield especially for small and multiple adenomas and was better in prediction of the correct localization. It could therefore serve as a second-line imaging modality.

Small Chyle Leak Localized on Lymphoscintigraphy with Single-Photon Emission Computed Tomography-Computed Tomography.

Chylothorax refers to the accumulation of triglyceride-rich fluid (chyle) within the pleural space. We described a case of spontaneous chylothorax in an infant. Lymphoscintigraphy was performed with 99 m-Tc sulfur colloid which showed tracer accumulation into thoracic cavity, and single-photon emission computed tomography/CT (SPECT/CT) revealed leak in the thoracic duct at D8 vertebral level as the cause. We, thus, emphasize the role of lymphoscintigraphy with SPECT/CT in identification of cause and guiding the management of chylothorax, especially when surgical treatment is planned.

18F]mFBG PET-CT for detection and localisation of neuroblastoma: a prospective pilot study

PurposeMeta-[18F]fluorobenzylguanidine ([18F]mFBG) is a positron emission tomography (PET) radiotracer that allows for fast and high-resolution imaging of tumours expressing the norepinephrine transporter. This pilot study investigates the feasibility of [18F]mFBG PET-CT for imaging in neuroblastoma.MethodsIn a prospective, single-centre study, we recruited children with neuroblastoma, referred for meta-[123I]iodobenzylguanidine ([123I]mIBG) scanning, consisting of total body planar scintigraphy in combination with single-photon emission computed tomography-CT (SPECT-CT). Within two weeks of [123I]mIBG scanning, total body PET-CTs were performed at 1 h and 2 h after injection of [18F]mFBG (2 MBq/kg). Detected tumour localisations on scan pairs were compared. Soft tissue disease was quantified by number of lesions and skeletal disease by SIOPEN score.ResultsTwenty paired [123I]mIBG and [18F]mFBG scans were performed in 14 patients (median age 4.9 years, n = 13 stage 4 disease and n = 1 stage 4S). [18F]mFBG injection was well tolerated and no related adverse events occurred in any of the patients. Mean scan time for [18F]mFBG PET-CT (9.0 min, SD 1.9) was significantly shorter than for [123I]mIBG scanning (84.5 min, SD 10.5), p < 0.01. Most tumour localisations were detected on the 1 h versus 2 h post-injection [18F]mFBG PET-CT. Compared to [123I]mIBG scanning, [18F]mFBG PET-CT detected a higher, equal, and lower number of soft tissue lesions in 40%, 55%, and 5% of scan pairs, respectively, and a higher, equal, and lower SIOPEN score in 55%, 30%, and 15% of scan pairs, respectively. On average, two more soft tissue lesions and a 6-point higher SIOPEN score were detected per patient on [18F]mFBG PET-CT compared to [123I]mIBG scanning.ConclusionResults of this study demonstrate feasibility of [18F]mFBG PET-CT for neuroblastoma imaging. More neuroblastoma localisations were detected on [18F]mFBG PET-CT compared to [123I]mIBG scanning. [18F]mFBG PET-CT shows promise for future staging and response assessment in neuroblastoma.Trial registrationDutch Trial Register NL8152.

Comparison of BMIPP-SPECT/CT to 18FDG-PET/CT for Imaging Brown or Browning Fat in a Preclinical Model.

Obesity is a leading cause of preventable death and morbidity. To elucidate the mechanisms connecting metabolically active brown adipose tissue (BAT) and metabolic health may provide insights into methods of treatment for obesity-related conditions. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18FDG-PET/CT) is traditionally used to image human BAT activity. However, the primary energy source of BAT is derived from intracellular fatty acids and not glucose. Beta-methyl-p-iodophenylpentadecanoic acid (BMIPP) is a fatty acid analogue amenable to in vivo imaging by single photon emission computed tomography/CT (SPECT/CT) when radiolabeled with iodine isotopes. In this study, we compare the use of 18FDG-PET/CT and 125I-BMIPP-SPECT/CT for fat imaging to ascertain whether BMIPP is a more robust candidate for the non-invasive evaluation of metabolically active adipose depots. Interscapular BAT, inguinal white adipose tissue (iWAT), and gonadal white adipose tissue (gWAT) uptake of 18FDG and 125I-BMIPP was quantified in mice following treatment with the BAT-stimulating drug CL-316,243 or saline vehicle control. After CL-316,243 treatment, uptake of both radiotracers increased in BAT and iWAT. The standard uptake value (SUVmean) for 18FDG and 125I-BMIPP significantly correlated in these depots, although uptake of 125I-BMIPP in BAT and iWAT more closely mimicked the fold-change in metabolic rate as measured by an extracellular flux analyzer. Herein, we find that imaging BAT with the radioiodinated fatty acid analogue BMIPP yields more physiologically relevant data than 18FDG-PET/CT, and its conventional use may be a pivotal tool for evaluating BAT in both mice and humans.

Head-to-head comparison of ventilation/perfusion single photon emission computed tomography/computed tomography and multidetector computed tomography angiography for the detection of acute pulmonary embolism in clinical practice.

Computed tomography angiography (CTA) and ventilation/perfusion (V/Q) single photon emission computed tomography/CT (SPECT/CT) images have been widely used to detect PE, but few studies have performed a direct comparison between them. We aimed to evaluate the performance of these tests in the same group of patients, selected from the routine practice of a general hospital. Patients with suspected acute PE were prospectively submitted to CTA and V/Q SPECT/CT. General radiologists and nuclear physicians, respectively, interpreted the images. Data regarding age, sex, time between examinations, symptoms, and Wells score were also recorded. The final diagnosis was decided through a consensus among the clinicians, taking into account clinical, laboratory, follow-up, and all imaging procedures data. Twenty-eight patients (15 male, 13 female, and median age of 51.5years) were studied. Median duration of the onset of symptoms was 4 (1-14)days, and the median Wells score was 3.5 (1.5-6). Sensitivity, specificity, positive and negative predictive values, and accuracy were 84.6%, 80.0%, 78.6%, 85.7%, and 82.1% for V/Q SPECT/CT, and 46.1%, 100%, 100%, 68.2%, and 75.0% for CTA. The overall agreement between the methods was 57.1%. Of the 22 patients with negative CTA, 10 (45.4%) had positives V/Q SPECT/CT and seven of them classified as true positives. Our results suggest that V/Q SPECT/CT is more sensitive and accurate than CTA when interpreted by general radiologists and nuclear medicine physicians.

Diagnostic value of single-photon emission computed tomography-CT foot and ankle studies.

The aim of this study is to determine the impact of foot and ankle single-photon emission computed tomography (SPECT) CT on patient management. A retrospective review over a 7-year period investigating whether the study identified or confirmed a source of symptoms. The electronic patient record was reviewed to see whether the test was helpful to the onward management of the patient. In total 44 patients were included and pathology was identified in 40 of the 44 patients, with four having normal studies. SPECT CT was deemed helpful in the management of 39 of the patients with the positive usefulness overall calculated as 89%. The remaining five patients where the test was not helpful have been discussed. SPECT-CT is a helpful imaging test in the diagnosis of foot and ankle disorders with 89% of studies being diagnostically useful.

DaPeCa-8: drawing the map of lymphatic drainage in patients with invasive penile cancer – evidence from SPECT/CT and sentinel node surgery

Background Anatomy of the lymphatic drainage guides the extent of inguinal lymph node dissection in penile cancer. Objective To prospectively assess the lymphatic drainage of penile cancer with single-photon emission computed tomography CT (SPECT-CT) and implications for the extent of inguinal lymph node dissection. Methods We assessed the lymphatic drainage of 62 patients with at least unilateral clinical lymph node-negative (cN0) status with SPECT-CT at our tertiary referral centre. We evaluated 122 cN0 inguinal basins and compared them to the histopathological outcome. The inguinal regions were divided into ten different Daseler zones on SPECT-CT. The surgical team filled in a corresponding scheme at sentinel node biopsy and sent lymph nodes from each Daseler zone individually for histopathological examination. Results SPECT-CT successfully visualized lymphatic drainage in 116 of the 122 cN0 inguinal basins (95.1%). The vast majority of sentinel nodes and all metastatic nodes were located in central and superior inguinal zones, including six metastatic nodes in lateral superior zones. Minimal lymphatic drainage was seen to the inferior Daseler zones and no metastatic deposits were located here. No direct pelvic drainage was observed. Conclusions Penile cancer lymphatic drainage is primarily to sentinel in the superior and central zones of Daseler. Colleagues practicing a modified inguinal lymph node dissection as a standard in cN0 patients are encouraged to include all these zones, while the inferior zones can be omitted. This study confirms the absence of lymphatic drainage directly to the pelvic region and supports the practice of omitting pelvic nodes from sentinel node biopsy.

Effects of Stimulating Local and Distal Acupoints on Diabetic Gastroparesis: A New Insight in Revealing Acupuncture Therapeutics.

One of the most important aspects of clinical acupuncture practice, like diabetic gastroparesis, is the selection of suitable acupoints. Furthermore, it is critical to examine the therapeutic impact differences between distal and local acupoints, as well as the prescription of their combination. In this study, diabetic gastroparesis rats were treated by needling Zhongwan (CV12) and Zusanli (ST36), and then used Single Photon Emission Computed Tomography-CT (SPECT-CT) technology to assess the effects of promoting gastric motility. In addition, morphological observation, immunohistochemical examination, and biomarker assays, such as determination of growth factor 1, motilin, and ghrelin contents in serum samples, were performed to better understand the impact of certain various acupuncture treatments. All of the therapies improved the symptoms of diabetic gastroparesis rats, according to the findings. Stimulating these acupoints, on the other hand, can have a different therapeutic effect. In addition, needling local and distal acupoints together can have an antagonistic or synergistic impact on specific physiological and biochemical indexes such as gastric motility, ghrelin, gastrin, and growth factor 1, among others. Our findings demonstrated the benefits of acupoints and acupuncture in the management of diabetic gastroparesis, as well as a new insight into acupuncture therapeutics.

Focal nodular marrow hyperplasia: Imaging features of 53 cases.

To describe the characteristic imaging features of focal nodular marrow hyperplasia (FNMH). Retrospective review of all patients with a diagnosis of FNMH between January 2007 and September 2019. The study included 53 patients, 7 males and 46 females with a mean age of 58 years (range 12-95 years). All had MRI with conventional spin echo sequences showing a poorly defined round/oval lesion with mild T1W iso/hyperintensity compared to skeletal muscle, low T2W turbo spin echo (TSE) signal intensity (SI) compared to marrow fat and variable SI on STIR, but never associated with reactive marrow oedema. All 53 patients had follow-up MRI, with all lesions remaining stable or partially resolving. In-phase (IP) and out-of-phase (OP) chemical shift imaging (CSI) was obtained in 31 of these, with 28 (90.3%) showing >20% SI drop on the OP sequence, while 3 (9.7%) demonstrated <20% SI drop. CT was available in 26 cases, 17 (65.4%) showing mild medullary sclerosis. Single-photon emission computed tomography CT (SPECT-CT) was available in four cases and Flourodeoxyglucose positron emission tomography CT (FDG PET-CT) in 2, all showing increased uptake. Focal uptake was also seen in three of eight patients who had undergone whole body bone scintigraphy. Only one lesion was biopsied, confirming FNMH. The imaging appearances of FNMH have been described on various modalities, particularly MRI with emphasis on the role of IP and OP CSI typically demonstrating >20% SI reduction. FNMH should be recognised and treated as a 'do not touch' lesion which does not require biopsy or prolonged follow-up. We describe and clarify the imaging characteristics of FNMH on MRI, including CSI, CT and various nuclear medicine modalities. An imaging algorithm is suggested for allowing a non-invasive diagnosis.

Computed Tomography (CT) Protocols Associated with Cardiac and Bone Single-Photon Emission Computed Tomography/CT (SPECT/CT) in Korea.

Single-photon emission computed tomography/computed tomography (SPECT/CT) is an advanced hybrid nuclear medicine technology that generates both functional and anatomical images in a single study. As utilization of SPECT/CT in Korea has been increasing, the purpose of this study was to survey its application of cardiac and skeletal SPECT/CT imaging for protocol optimization. We surveyed CT protocols established for cardiac and skeletal SPECT/CT. We searched the guidelines for the CT protocols for SPECT/CT and reviewed the literature recently published. Among 36 hybrid SPECT scanners equipped with four or more multi-channel detector CTs (MDCTs), 18 scanners were used to perform cardiac studies at both very low current CT (30-80mA; 11.1%) and ultra-low current CT (13-30mA; 88.9%). Among the 33 canners, very low current (≤ 80mA) CT or low current CT (80-130mA) was used in 23.5%, and 41.8% for spine disorders, and in 36.4% or 30.3% for foot/ankle disorders, respectively. In the CT reconstructions, slice thickness of 5mm for cardiac studies was most commonly used (94.4%); thinner slices (0.6-1.0mm) for spine and foot/ankle studies were used in 24.2% and 45.5%, respectively. We also reviewed the international guidelines. The results and current recommendations will be helpful for optimizing CT protocols for SPECT/CT. Optimization of SPECT/CT protocols will be required for generating the proper strategy for the specific lesions and clinical purpose.

MP62-18 PRIMARY METASTASIS STAGING USING 18 F-PSMA-1007 PET-CT IN HIGH-RISK PROSTATE CANCER

MP62-18 PRIMARY METASTASIS STAGING USING ¹⁸ F-PSMA-1007 PET-CT IN HIGH-RISK PROSTATE CANCER

An On-Board Spectral-CT/CBCT/SPECT Imaging Configuration for Small-Animal Radiation Therapy Platform: A Monte Carlo Study.

This study investigated the feasibility of a highly specific multiplexed image-guided small animal radiation therapy (SART) platform based on triple imaging from on-board single-photon emission computed tomography (SPECT), spectral-CT, and cone-beam CT (CBCT) guidance in radiotherapy treatment. As a proof-of-concept, the SART system was built with the capability of triple on-board image guidance by utilizing an x-ray tube and a single cadmium zinc telluride (CZT) semiconductor photon-counting imager via a Monte Carlo simulation study. The x-ray tube can be set at a low tube current for imaging mode and a high tube current for radiation therapy mode, respectively. In the imaging mode, both x-ray and gamma-ray projection data were collected by the imager to reconstruct CBCT, SPECT and spectral CT images of small animals being treated. The modulation transfer function (MTF) of the pixelated CZT imager measured was 8.6 lp/mm. The overall performances of the CBCT and SPECT imaging of the system were evaluated with sufficient spatial resolution and imaging quality to be fitted into the SART platform. The material differentiation and decomposition capacities of spectral CT within the system were verified using K-edge imaging, image-based optimal energy weighted imaging, and image-based linear material decomposition methods. The triple imaging capability of the system was demonstrated using a PMMA phantom containing gadolinium, iodine and radioisotope 99mTc inserts. All the probes were clearly identified in the registered image. The results demonstrated that a novel SART platform with high-quality on-board CBCT, spectral-CT, SPECT image guidance is technically feasible by using a single semiconductor imager, thus affording comprehensive image guidance from anatomical, functional, and molecular levels for radiation treatment beam delivery.

Use of autologous 99mTechnetium-labelled neutrophils to quantify lung neutrophil clearance in COPD

RationaleThere is a need to develop imaging protocols which assess neutrophilic inflammation in the lung.AimTo quantify whole lung neutrophil accumulation in (1) healthy volunteers (HV) following inhaled lipopolysaccharide (LPS) or...

Primary Metastasis Staging Using&nbsp;18F-PSMA-1007 PET-CT in High-Risk Prostate Cancer: A Prospective Comparative Study of Advanced and Traditional Imaging Modalities

Background: Computed tomography (CT) and bone scintigraphy are the imaging modalities currently used for primary metastasis staging of high-risk prostate cancer (PCa). This trial compared these standard staging modalities with potentially more accurate imaging modalities: single photon emission computed tomography-CT (SPECT-CT), magnetic resonance imaging (MRI), prostate specific membrane antigen positron emission tomography (PSMA PET). Methods: This prospective, registered, single-centre, open-label, single-arm trial enrolled patients with primary high-risk PCa. Results of bone scintigraphy and CT were compared with 99mTc-HMDP SPECT-CT, 1.5T whole-body MRI using diffusion-weighted imaging and 18 F-PSMA-1007 PET-CT. Each imaging modality was reviewed by two independent experts blinded for the other modalities. The lesions were classified as benign, equivocal or malignant. Pessimistic and optimistic analyses were performed to resolve equivocal lesion status. Based on clinical data, including follow-up investigations, the best valuable comparator was defined at lesion level in multidisciplinary consensus meetings. Findings: 79 men were included and underwent all imaging modalities, except for one cancelled MRI due to claustrophobia. Mean age was 70 years and median PSA 12 ng/ml (range: 3-2000). Metastatic disease was detected in 27 (34%) patients. In pessimistic and optimistic analysis at patient, region and lesion levels, PSMA PET-CT was superior to all other modalities concerning sensitivity, and the area under curve values (AUC) at the bone region, while maintaining high specificity and demonstrating the highest inter-reader agreement. AUC for detection of bone metastasis for PSMA PET-CT was 0·94 (95%Cl;0·90-0·99) and 0·96 (95%CI;0·92-0·99) (reader 1, and reader 2, respectively) while AUC for all other modalities was in the range of 0·55-0·76. PSMA PET-CT revealed metastatic disease in 18/27 patients where standard imaging was negative. Interpretation: 18F-PSMA-1007 PET-CT outperformed other imaging methods in primary metastasis staging of high-risk PCa. We recommend further evaluation of this method as a new reference standard. Trial Registration number: (ClinicalTrials.gov NCT03537391). Funding Statement: This study was financially supported by grants from Finnish Government Research and Development Funds for Medical Research, Turku University Hospital and TYKS-SAPA Research Fund. Declaration of Interests: Dr. Anttinen reports grants from Profound Medical Inc, Finnish Urological Research Foundation and Finnish Urological Association, outside the submitted work. Dr. Ettala reports non-financial support from Ferring Pharmaceuticals Inc, SwanMedica and Pierre-Fabre Pharma Norden AB, and personal fees from Astellas, outside the submitted work. Dr. Sandell reports personal fees from Roche, outside the submitted work. Dr. Taimen reports personal fees from Roche, AstraZeneca and MSD, and non-financial support from MSD, all outside the submitted work. Dr. Bostrom reports grants from the Cancer Foundation Finland, personal fees from Profound Medical Inc and Janssen-Cilag Company, outside the submitted work. The other authors declare that there is no conflict of interest regarding the publication of this article. Ethical Approval Statement: The trial protocol, included in the Supplemental material, was approved by the ethics committee of the Hospital District of Southwest Finland, and written informed consent was obtained from all participants. The trial was performed in accordance with the principles of the Declaration of Helsinki.

Umbilical Varices: A Potential Pitfall in Gastrointestinal Bleed Scintigraphy Interpretation.

Tc-99m labeled red blood cell (RBC) scintigraphy is commonly used in the evaluation of acute gastrointestinal (GI) bleeding. On Tc-99m RBC studies, GI bleeding is seen as an initial focus of increased radiotracer activity that on subsequent images increases in intensity and changes position in a pattern that confirms to segments of bowel. We report a case of a patient with multiple episodes of GI bleeding referred to detect the source of bleeding. A Tc-99m labeled RBC scan was performed and the findings showed a focal abnormal hot spot in the mid quadrant of the abdomen, seen promptly in initial dynamic images. Subsequent static and single-photon emission computed tomography-CT (SPECT-CT) images found it to be umbilical varices. Most varices fill promptly as in this case and should not be misinterpreted as a focus of hemorrhage. SPECT-CT should be used in such cases so that that false-positive interpretation can be avoided.

Incidental Detection of Bilateral Large Urinary Bladder Diverticulae on Tc99m Ethylene Dicysteine Renography with Single-photon Emission Computed Tomography-Computed Tomography.

The complementary anatomical and functional information provided by hybrid imaging with single-photon emission computed tomography-CT (SPECT-CT) is a very useful imaging tool in selected cases where anatomical information is lacking as in the scenario of dynamic renal scintigraphy. The authors present a case of a 5-year-old male child with symptoms suggestive of cutis laxa with urinary tract infection. The child underwent dynamic renal scintigraphy with Tc99m ethylene dicysteine for cortical function and drainage assessment. Hybrid SPECT/CT proved valuable in the child in identification of the bilateral gross urinary bladder diverticulae.

SPECT image segmentation for estimation of tumour volume and activity concentration in 177Lu-DOTATATE radionuclide therapy

BackgroundDosimetry in radionuclide therapy has the potential to allow for a treatment tailored to the individual patient. One therapeutic radiopharmaceutical where patient-specific dosimetry is feasible is 177Lu-DOTATATE, used for the treatment of neuroendocrine tumours. The emission of gamma photons by 177Lu allows for imaging with SPECT (single photon emission computed tomography). One important step for dosimetry using this imaging technique is the SPECT image segmentation, which needs to be robust and accurate for the estimated quantities to be reliable. This work investigates different methods for automatic tumour delineation in 177Lu-DOTATATE SPECT images.Three segmentation methods are considered: a fixed 42% threshold (FT), the Otsu method (OM) and a method based on Fourier surfaces (FS). Effects of including resolution compensation in the iterative SPECT image reconstruction are also studied. Evaluation is performed based on Monte Carlo-simulated SPECT images from 24 h and 336 h post injection (p.i.), for determination of the volume, activity concentration and dice similarity coefficient. In addition, patient data are used to investigate the correspondence of tumour volumes when delineated in SPECT or morphological CT or MR images. Patient data are also used to examine the sensitivity to the operator-dependent initialization.ResultsFor simulated images from 24 h p.i. reconstructed without resolution compensation, a volume and activity-concentration root-mean-square error below 15% is typically obtained for tumours above approximately 10 cm3 when using OM or FS, while FT performs considerably worse. When including resolution compensation, the tumour volume becomes underestimated and the activity concentration overestimated. The FS method appears to be robust to noise, as seen for the 336 h images. The differences between the tumour volumes estimated from the SPECT images and the volumes estimated from morphological images are generally larger than the discrepancies seen for the simulated data sets.ConclusionsSegmentation results are encouraging for future dosimetry of tumours with volumes above approximately 10 cm3. Using resolution compensation in the reconstruction may have a negative effect on volume estimation.

The Incremental Prognostic Value of Cardiac Computed Tomography in Comparison with Single-Photon Emission Computed Tomography in Patients with Suspected Coronary Artery Disease

BackgroundCoronary computed tomographic angiography (CCTA) facilitates comprehensive evaluation of coronary artery disease (CAD), including plaque characterization, and can provide additive diagnostic value to single-photon emission computed tomography (SPECT). However, data regarding the incremental prognostic value of CCTA to SPECT remain sparse. We evaluated the independent and incremental prognostic value of CCTA, as compared with clinical risk factors and SPECT.Materials and methodsA total of 1,077 patients with suspected CAD who underwent both SPECT and cardiac CT between 2004 and 2012 were enrolled retrospectively. Presence of reversible or fixed perfusion defect (PD) and summed stress score were evaluated on SPECT. Presence, extent of coronary atherosclerosis and diameter stenosis (DS) were evaluated on CCTA. Plaque composition was categorized as non-calcified, mixed, or calcified according to the volume of calcified component (>130 Hounsfield Units). Patients were followed up for the occurrence of adverse cardiac events including cardiac death, non-fatal myocardial infarction, unstable angina, and late revascularization (>90 days after imaging studies).ResultsDuring follow-up (median 23 months), adverse cardiac events were observed in 71 patients (6.6%). When adjusted for clinical risk factors and SPECT findings, the presence of any coronary plaque, any plaque in ≥3 segments, coronary artery calcium score (CACS) ≥400, a plaque ≥50% DS, presence of non-calcified plaque (NCP) or mixed plaque (MP), and NCP/MP in ≥2 segments were independent predictors of adverse cardiac events; however, the presence of calcified plaque (CP) was not. Conventional CCTA findings, including CACS ≥400 and a plaque ≥50% DS, demonstrated incremental prognostic value over clinical risk factors and SPECT (χ² 54.19 to 101.03; p <0.001). Addition of NCP/MP in ≥2 segments resulted in further significantly improved prediction (χ² 101.03 to 113.29; p <0.001).ConclusionComprehensive CCTA evaluation of coronary atherosclerosis provides independent and incremental prognostic value in relation to SPECT evaluation of myocardial ischemia. Specifically, segmentally-analyzed plaque composition with CCTA provides further risk stratification in addition to CACS and DS.

The value of MRI combined with single photon emission computed tomography-CT for the diagnosis of nasopharyngeal carcinoma with early skull base bone invasion and the affect on clinical decision

Objective To analyze the value of MRI combined with single photon emission computed tomography-CT (SPECT-CT) for the diagnosis of nasopharyngeal carcinoma with early skull base bone invasion and the effect on clinical decision. Methods This retrospective study included 195 pathologically proven nasopharyngeal carcinoma patients with complete clinical and follow-up data, which did not find the signs of skull base bone invasion by CT and be subsequently performed MRI and SPECT-CT. The MRI and SPECT-CT images were respectively analyzed and the positive or negative judgment was made on whether there was skull base bone invasion. Clinical doctors made the routine clinical decision according to MR results, and then made the combined clinical decision based on the results of MR combined with SPECT-CT. The changes between 2 clinical decisions were analyzed. To assess the value of MR, SPECT-CT and combined examination in the diagnosis of skull base bone invasion on the basis of comprehensive clinical results (including symptoms, imaging and follow up, etc) as qualitative criteria. The diagnostic power of MRI, SPECT-CT and combined examination was analyzed by ROC. Results Compared with the routine clinical decisions, combined clinical decisions (44.6%, 87/195) were changed in 87 cases, including 21 cases with new diagnosis of skull base bone invasion, 46 cases with skull base invasion range increased and 87 cases with treatment plan changes. In 195 cases, 114 cases were confirmed to have the skull base bone invasion by comprehensive clinical results. When MRI was positive and SPECT-CT positive, MRI negative and SPECT-CT negative, MRI positive and SPECT-CT negative, MRI negative and SPECT-CT positive, the presence of skull base bone invasion respectively were 100.0% (74/74), 0 (58/58), 66.7% (16/24), 61.5% (24/39). MRI and (or) SPECT-CT positive was regarded as positive, it was used as the criterion of combined examination. For skull base bone invasion, MRI, SPECT-CT and combined examination had the sensitivities of 78.95% (90/114), 85.96% (98/114), and 100.00% (114/114), the specificities of 90.12% (73/81), 81.48% (66/81), 71.60% (58/81), the area under the ROC curve of 0.845, 0.837, 0.858; and the misdiagnosis rate of 16.41%, (32/195), 15.90% (31/195), 11.79% (23/195). Conclusion MRI combined with SPECT-CT can improve the accuracy of diagnosing skull base bone invasion and effectively affect the clinical decision of nasopharyngeal carcinoma. Key words: Nasopharyngeal neoplasm; Magnetic resonance imaging; Tomography, emission-computed, single-photon; Skull base