Low-dose Non-contrast CT Research Articles

Risk Factors of Asymptomatic Kidney Stone Passage in Adults with Recurrent Kidney Stones.

Kidney stones are a common health problem and are characterized by a high risk of recurrence. A certain number of kidney stones passed asymptomatically. Data regarding the frequency of asymptomatic spontaneous stone passages are limited. To assess the frequency of asymptomatic spontaneous stone passage and its covariates, we conducted a post-hoc analysis of the prospective randomized NOSTONE trial. All asymptomatic spontaneous stone passages were identified by comparing the total number of kidney stones on low-dose non-contrast CT imaging at the beginning and end of the study, considering symptomatic stone passages and surgical stone removal. The statistical analysis focused on the association of independent variables and the number of asymptomatic spontaneous stone passages using linear regression analyses. Of the 416 randomized patients, 383 with both baseline and end-of-study CT were included in this analysis. The median follow-up period was 35 months, the median patient age was 49 years (IQR:40 - 55), and 20% of the patients were female. A total of 442 stone events occurred in 209 out of 383 (55%) patients: 217 out of 442 (49%) were symptomatic spontaneous stone passages, 67 out of 442 (15%) were surgically removed stones, and 158 out of 442 (36%) were asymptomatic spontaneous stone passages. The median size of asymptomatic stones (2.4 mm; IQR:1.95-3.4) and the size of symptomatic stones (2.15 mm; IQR:1.68-2.79) that passed spontaneously were not significantly different (p=0.37). The number of asymptomatic spontaneous stone passages was significantly associated with a higher number of stones on CT at randomization (P=0.001). Limitations include the lack of data on stone size at the time of passage and overrepresentation of White men. Asymptomatic stone passage was common in patients with recurrent calcium-containing kidney stones. The higher the number of stones at presentation, the more likely it was that a kidney stone would spontaneously pass over time without causing any symptoms.

Renal colic

Renal colic accounts for 5-10% of all emergency department visits, making it acommon condition in acute medicine. The typical clinical presentation is an early indication of urolithiasis. Diagnostic measures include laboratory tests, ultrasound, and low-dose noncontrast computed tomography (CT) scans. Kidney, ureter, bladder (KUB) plain film radiography has been widely replaced by low-dose noncontrast CT with similar radiation dosage. In special patient groups such as children or pregnant women, ionizing radiation should be avoided if possible. General measures involve pain management (non-steroidal anti-inflammatory agents, opioids) and empirical antibiotic treatment for suspected bacterial infection. Depending on the location/size of the stone, pharmacological stone expulsion therapy may be considered. In cases of obstructive pyelonephritis or acute renal insufficiency, early urinary drainage (JJ stent/nephrostomy) is recommended. Definitive stone removal may be performed primarily in some cases (rather small and rather distal ureterolithiasis). It is common to schedule stone removal as asecondary intervention.

Correlation Diagnostic Contribution of SPECT/CT Imaging to 99mTc-DTPA Dynamic Scintigraphy in Patients with Different Renal Pathologies

Introduction: Dynamic renal scintigraphy with 99mTechnetium diethylenetriaminepentaacetic acid (99mTc-DTPA) is a widely performed imaging method to evaluate kidney function of patients with various renal pathologies. However the one-stop-shop combination with subsequent SPECT/CT imaging is a rarely discussed topic. Objective: The aim of the study was to evaluate the diagnostic benefits of SPECT/CT imaging to 99mTc-DTPA dynamic renal scintigraphy. Materials and Methods: A group of 32 patients (21 females and 11 males) who underwent dy- namic nephroscintigraphy with subsequent SPECT/CT was retrospectively studied. A dose of 185MBq (5mCi) 99mTc-DTPA was intravenously applied. A low-dose non-contrast CT protocol was used for attenuation correction and anatomical correlation. Results: Impaired relative renal function in various degrees of left kidney was detected in 18 patients (56%) and of right kidney in 14 patients (44%). SPECT/CT imaging identified the particular cause for the renal dysfunction in the analyzed subjects. The hybrid imaging demonstrated urolithiasis in 11 patients, postoperative ureteral strictures in 5 patients, diagnosed urological cancer in 4 patients and external compression of ureter in 2 patients as a possible obstructive cause. Congenital renal anomalies were the identified causes of impaired renal function in 10 patients – hypoplastic kidney in 4 patients, duplex kidney in 2 patients, multiple cortical cysts in 2 patients, aberrant vessel obstructing the pyeloureteral segment in 1 patient and horseshoe kidney in 1 patient. Conclusion: Dynamic renal scintigraphy combined with SPECT/CT is a very useful clinical tool, by providing not only functional but also anatomical information of the urinary tract, especially in the evaluation of obstructive uropathies and congenital renal abnormalities, that has the potential to change clinical management.

Role of CT attenuation correction gated SPECT MPI in prediction of pulmonary hypertension

ObjectiveTo elucidate the value of gated SPECT-MPI using CT attenuation correction (AC) for prediction of pulmonary hypertension (PHT) in coronary patients by estimation of reliability of non-contrast CT in measurement of main pulmonary artery diameter (MPAd) as well as by assessment of potential predictive role of gated parameters as beneficial accessory findings. BackgroundContrast-enhanced CT is known as an accurate tool for assessment of MPAd to predict PHT. [1] The low-dose non-contrast CT which is used for AC in MPI study, however, has an unclear value in precise vascular diameter measurement; it is also uncertain whether gated parameters could help to predict PHT. Methods and patientsA total of 207 patients, who had a transthoracic echocardiography and MPI with an interval of maximum one month, underwent this retrospective study. PHT was defined as a RVSP ≥36 mmHg by echocardiography; peak tricuspid regurgitation velocity (PTRV) was also calculated to use as a criterion for PHT. Of all subjects, 120 had RVSP ≥ 36 and 87 showed RVSP < 36; there also were 191 and 16 patients with PTRV ≤ 3.4 m/s and >3.4 m/s, respectively. Comparison was made unconnectedly between each group regarding the echocardiography results with the MPI parameters, with and without CT-AC, including MPAd derived from CT as well as RV/LV uptake ratio, shape index and septal wall motion and thickening scores to define the best indicators of PHT. ResultsThere was a significant association between established benchmark of PHT in echocardiography (RVSP), with MPAd derived from non-contrast CT as well as with LV shape index from gated study and RV/LV uptake ratio acquired from non-AC SPECT-MPI. Also, stress and rest RV/LV uptake ratio, MPAd, LV end-systolic and LV end-diastolic shape indexes are significantly higher in patients with RVSP ≥ 36 mmHg compare to patients with RVSP < 36 mmHg. ConclusionsGated-SPECT-MPI using CT-AC can predict PHT by reliable estimation of MPAd as well as by defining RV/LV uptake ratio and shape index, providing an added clinical value for this invaluable modality in cardiac patients.

The Presence of an Arteria Lusoria Should Be Checked When Reporting 18 F-FCH PET/CT Performed to Localize Hyperfunctioning Parathyroid Glands.

Nonrecurrent inferior laryngeal nerve (NRILN) is a rare anatomical variant, which significantly increases the risk of nerve injury during neck surgery, for example, thyroidectomy or parathyroidectomy (PTX). The absence of the brachiocephalic trunk and presence of arteria lusoria (AL) are strong predictors of NRILN in the right neck. FCH PET/CT is now a recognized imaging modality in hyperparathyroidism (HPT). We report 2 patients with primary or renal HPT in whom FCH PET detected right HFPTs and low-dose noncontrast CT evidenced AL. The NRILN was thus preserved during PTX. We recommend searching for AL on FCH PET/CT (even low-dose) in HPT before PTX.

Comparison of Low-Dose Non-contrast CT in Detecting Anatomical and Surgically Important Variants of Paranasal Sinuses to Standard Dose Non-contrast CT: Experience from a Tertiary Care Hospitalin Sub-Himalayan Region of Northern India.

Computed tomography (CT) is the gold standard for diagnosing sinusitis and anatomical variations and a guide for paranasal sinus (PNS) surgeries. High doses of radiation lead to increased risk of head and neck malignancies, radiation-induced cataracts, hypothyroidism, and hyperthyroidism. The purpose of this study was to assess the effectiveness of low-dose CT as compared to standard-dose CT in the identification of anatomical variants of paranasal sinus and rhinosinusitis. This was a prospective cross-sectional study consisting of 72 patients who were divided equally into cases (underwent low-dose CT for PNS) and controls (underwent CT for PNS using standard dose protocols). Prevalence of anatomical variants and sinusitis were compared. Image quality was assessed using volume CT dose index (CTDIvol), dose length product (DLP), scan length, and noise. Subjective assessment was done by two radiologists, and scores were given. The comparison and analysis of the quantitative and qualitative variables were done. Anatomical variants were comparable among cases and controls, with post-sellar sphenoid being most common and paradoxical middle turbinate being least common surgically important variant. The difference in meanSD of CTDIvol (mGy), DLP (mGy-cm), effective dose (mSv), globe, and air noise between low and standard doses was statistically significant. A moderate agreement (with kappa 0.50) in cases and substantial agreement (with kappa 0.69) in controls was observed between both observers. Low-dose CT PNS and standard-dose CT PNS are comparable in delineating the paranasal sinus anatomy, with a 3.53× reduction of effective radiation dose to patients.

Fully Automated Longitudinal Assessment of Renal Stone Burden on Serial CT Imaging Using Deep Learning.

Purpose: Use deep learning (DL) to automate the measurement and tracking of kidney stone burden over serial CT scans. Materials and Methods: This retrospective study included 259 scans from 113 symptomatic patients being treated for urolithiasis at a single medical center between 2006 and 2019. These patients underwent a standard low-dose noncontrast CT scan followed by ultra-low-dose CT scans limited to the level of the kidneys. A DL model was used to detect, segment, and measure the volume of all stones in both initial and follow-up scans. The stone burden was characterized by the total volume of all stones in a scan (SV). The absolute and relative change of SV, (SVA and SVR, respectively) over serial scans were computed. The automated assessments were compared with manual assessments using concordance correlation coefficient (CCC), and their agreement was visualized using Bland-Altman and scatter plots. Results: Two hundred twenty-eight out of 233 scans with stones were identified by the automated pipeline; per-scan sensitivity was 97.8% (95% confidence interval [CI]: 96.0-99.7). The per-scan positive predictive value was 96.6% (95% CI: 94.4-98.8). The median SV, SVA, and SVR were 476.5 mm3, -10 mm3, and 0.89, respectively. After removing outliers outside the 5th and 95th percentiles, the CCC measuring agreement on SV, SVA, and SVR were 0.995 (0.992-0.996), 0.980 (0.972-0.986), and 0.915 (0.881-0.939), respectively Conclusions: The automated DL-based measurements showed good agreement with the manual assessments of the stone burden and its interval change on serial CT scans.

Decreased liver-to-spleen ratio in low-dose computed tomography as a biomarker of fatty liver disease reflects risk for myocardial ischaemia.

A strong association between fatty liver disease (FLD) and coronary artery disease is consistently reported. Our aim was to evaluate whether FLD diagnosed using low-dose non-contrast computed tomography (LDCT), as a by-product of myocardial perfusion imaging (MPI), is associated with myocardial ischaemia or left ventricular function parameters. We analysed 742 patients who had undergone MPI using single photon emission computed tomography (SPECT) and LDCT. A liver-to-spleen ratio (in Hounsfield units) of <1 was defined as FLD. Myocardial ischaemia was defined as a summed difference score (SDS) ≥3. Left ventricular size and systolic function were assessed from the electrocardiogram-gated SPECT. FLD patients were younger (63 vs. 68 years) and had a higher body mass index (34.6 vs. 29.0 kg/m2) and a higher SDS (2.65 vs. 1.63), P < 0.001 for all. Independently of several possible confounding factors including traditional risk factors, patients with FLD had a 1.70-fold risk of ischaemia (95% confidence interval 1.11-2.58, P = 0.014). Left ventricular end-diastolic volume (109 vs. 109 mL) and ejection fraction (61 vs. 61%) were comparable in those with and without FLD (non-significant for both). With the help of LDCT, it is possible to identify FLD, which is associated with an increased risk of myocardial ischaemia. Therefore, evaluation of FLD from LDCT is recommended along with MPI.

Appropriate Imaging Modalities in the Emergency Department for Assessment of Renal Stones

Introduction:Urolithiasis prevalence is approximately 15-20%, the third most common urological presentation to emergency departments (ED). In the ED, renal stones are usually diagnosed by clinical presentation, but imaging modalities play a role in confirmation and exclusion of hydronephrosis. 85% of stones are calcium oxalate/calcium phosphate, which are radio opaque, and 15% are radiolucent uric acid or cysteine stones. Non-contrast CT scans have 95% and 97% sensitivity and specificity rates, while x-rays have 57% and 76% respectively. In Wexford General Hospital, radiology prefers plain film x-rays prior to CT scans in assessing kidney stones.Method:The aim of this study was to assess the sensitivity of x-rays in patients undergoing low dose non-contrast CT for kidney stones and to apply this information to clinical practice. A retrospective audit was conducted using NIMIS/PACS from December 1, 2021-March 31,2022. All patients who underwent CT KUBS for evaluation of renal stones were included, and CT KUB findings were compared with initial x-ray findings.Results:A CT KUB was performed on 56 patients to assess renal stones, and 29 patients had renal stones. Among 29 patients, 21 had x-rays and CT scans performed, and 12 had x-ray findings that indicated renal stones, indicating 57% sensitivity. The study found 36 patients had x-rays for renal stones, but no CT scan was scheduled for 15 patients who might have undiagnosed radiolucent stones.Conclusion:Radiological imaging plays a central role in the management of suspected renal stones. CT KUB is a useful tool for evaluating patients with radio-opaque kidney stones as well as detecting radiolucent stones and renal pathologies that can be missed with plain radiographs. Low-dose CT KUB is recommended as a first-line investigation for renal stone patients to reduce radiation risks and unnecessary abdominal x-rays while assisting clinicians in accurately diagnosing patients and excluding other possible causes.

69-Year-Old Man With Dysuria and Right Lower Abdominal Pain

69-Year-Old Man With Dysuria and Right Lower Abdominal Pain

AB047. SOH22ABS079. Low-dose non-contrast computed tomography scan in suspected renal colic in adult: are we complying with guidelines?

Background: Adults with suspected renal colic should have low-dose non-contrast computed tomography (LDNCCT) kidney-ureter-bladder (KUB) within 24 hours of presentation as per the National Institute for Health and Care Excellence (NICE) guideline 29th July 2020. LDNCCT should be performed within 24 hours of presentation, unless it is contraindicated, to prevent delays to diagnosis and treatment. Delay in treatment of obstructed kidney can result in permanent damage to kidney function. Aim of this study was to assess the compliance to the existing NICE guidelines on getting LDNCCT for patients with suspected renal colic in our tertiary care university teaching hospital.

Augmented Reality-Assisted Biopsy of Soft Tissue Lesions.

Guided biopsy of soft tissue lesions can be challenging in the presence of sensitive organs or when the lesion itself is small. Computed tomography (CT) is the most frequently used modality to target soft tissue lesions. In order to aid physicians, small field of view (FOV) low dose non-contrast CT volumes are acquired prior to intervention while the patient is on the procedure table to localize the lesion and plan the best approach. However, patient motion between the end of the scan and the start of the biopsy procedure can make it difficult for a physician to translate the lesion location from the CT onto the patient body, especially for a deep-seated lesion. In addition, the needle should be managed well in three-dimensional trajectories in order to reach the lesion and avoid vital structures. This is especially challenging for less experienced interventionists. These usually result in multiple additional image acquisitions during the course of procedure to ensure accurate needle placement, especially when multiple core biopsies are required. In this work, we present an augmented reality (AR)-guided biopsy system and procedure for soft tissue and lung lesions and quantify the results using a phantom study. We found an average error of 0.75 cm from the center of the lesion when AR guidance was used, compared to an error of 1.52 cm from the center of the lesion during unguided biopsy for soft tissue lesions while upon testing the system on lung lesions, an average error of 0.62 cm from the center of the tumor while using AR guidance versus a 1.12 cm error while relying on unguided biopsies. The AR-guided system is able to improve the accuracy and could be useful in the clinical application.

Incidence of clinically significant perforation at low dose non-contrast CT and its value prior to same day CT colonography following incomplete colonoscopy.

Routine low dose non-contrast CT of the abdomen and pelvis has been suggested prior to same day completion CT colonography (CTC) to assess for occult perforation at preceding incomplete colonoscopy, before further gaseous insufflation at CTC. The aim of our study is to examine the incidence of clinically significant perforation at low dose CT. We also examine the benefits of low dose pre-scan in assessing adequacy of bowel preparation and identifying any other relevant contraindications to CT colonography. We conducted a retrospective review of all low dose non-contrast CTs performed following failed colonoscopies over a 4-year period (n = 392). We also assessed the adequacy of bowel preparation on a scale of 1-5, in order of increasingly adequate preparation. Incidentally noted bowel pathology and contraindications to CT colonography were also recorded. No perforation was identified either prospectively or in the course of our retrospective review. However, 15 patients (3.8%) were found to have potential contraindications to CT colonography, including: acute diverticulitis, acute colitis, and poor bowel preparation. Overall, the bowel preparation was felt to be adequate (≥ 3) in 86% percent of patients. Two patients (0.5%) identified prospectively had their CT colonography postponed due to poor bowel preparation.

Baseline findings of the population-based, randomized, multifaceted Danish cardiovascular screening trial (DANCAVAS) of men aged 65-74 years.

The challenge of managing age-related diseases is increasing; routine checks by the general practitioner do not reduce cardiovascular mortality. The aim here was to reduce cardiovascular mortality by advanced population-based cardiovascular screening. The present article reports the organization of the study, the acceptability of the screening offer, and the relevance of multifaceted screening for prevention and management of cardiovascular disease. Danish men aged 65-74 years were invited randomly (1 : 2) to a cardiovascular screening examination using low-dose non-contrast CT, ankle and brachial BP measurements, and blood tests. In all, 16 768 of 47 322 men aged 65-74 years were invited and 10 471 attended (uptake 62·4 per cent). Of these, 3481 (33·2 per cent) had a coronary artery calcium score above 400 units. Thoracic aortic aneurysm was diagnosed in the ascending aorta (diameter 45 mm or greater) in 468 men (4·5 per cent), in the arch (at least 40 mm) in 48 (0·5 per cent) and in the descending aorta (35 mm or more) in 233 (2·2 per cent). Abdominal aortic aneurysm (at least 30 mm) and iliac aneurysm (20 mm or greater) were diagnosed in 533 (5·1 per cent) and 239 (2·3 per cent) men respectively. Peripheral artery disease was diagnosed in 1147 men (11·0 per cent), potentially uncontrolled hypertension (at least 160/100 mmHg) in 835 (8·0 per cent), previously unknown atrial fibrillation confirmed by ECG in 50 (0·5 per cent), previously unknown diabetes mellitus in 180 (1·7 per cent) and isolated severe hyperlipidaemia in 48 men (0·5 per cent). In all, 4387 men (41·9 per cent), excluding those with potentially uncontrolled hypertension, were referred for additional cardiovascular prevention. Of these, 3712 (35·5 per cent of all screened men, but 84·6 per cent of those referred) consented and were started on medication. Multifaceted cardiovascular screening is feasible and may optimize cardiovascular disease prevention in men aged 65-74 years. Uptake is lower than in aortic aneurysm screening.

Ultra-low-dose limited renal CT for volumetric stone surveillance: advantages over standard unenhanced CT.

To describe and validate a novel CT approach using volumetric analysis for renal stone surveillance. This prospective trial consisted of a standard low-dose non-contrast CT (SLD) of the abdomen and pelvis, immediately followed by an ultra-low-dose non-contrast CT (ULD) with reconstruction limited to the kidneys. A novel dedicated software tool was applied that automates stone volume, density, and maximum linear size. Manual linear stone size was measured by a radiology fellow and urology resident for comparison. CT dose and clinical charges were considered. Twenty-eight stones in 16 patients were analyzed. Mean effective dose of ULD CT was 0.57mSv, an average 92% lower than the SLD CT dose. For SLD, mean size ± SD (range) (mm) was 7.9 ± 6.2 (2.6-30.5) for Reader 1, 7.3 ± 6 (2.4-30.7) for Reader 2, and 9.3 ± 6.4 (3.7-33.1) for the automated software. For ULD, mean size ± SD (range) (mm) was 7.3 ± 6 (2.5-30.5) for Reader 1, 7.2 ± 6.1 (2.1-30.7) for Reader 2, and 9.1 ± 6.4 (4.2-32.8) for the automated software. Automated stone diameters were larger than manual diameters for 27/28 stones (mean difference, 23%); difference was ≥ 2mm in 30%. Average variability between manual measurements was 8.6% (SLD) and 7.8% (ULD), but was 0% for the automated technique. Our institutional charge for ULD renal CT is slightly less than renal US, and > 4× less than SLD CT. The Medicare global fee for the ULD renal CT is less than the SLD CT of the abdomen and pelvis. This focused stone surveillance CT protocol is lower cost and lower dose compared to the standard CT approach. Automated assessment of stone burden provides improved reproducibility over manual linear measurement and offers the advantages of 3D measurements and volumetry. We now offer and perform this protocol in routine clinical practice for stone surveillance.

Abdominal Radiography With Digital Tomosynthesis: An Alternative to Computed Tomography for Identification of Urinary Calculi?

ObjectiveTo compare the accuracy of plain abdominal radiography (kidneys, ureter, and bladder [KUB]) with digital tomosynthesis (DT) to noncontrast computed tomography (NCCT), the gold standard imaging modality for urinary stones. Due to radiation and cost concerns, KUB is often used for diagnosis and follow-up of nephrolithiasis. DT, a novel technique that produces high-quality radiographs with less radiation and/or cost than low-dose NCCT, has not been assessed in this situation. Materials and MethodsSeven fresh tissue cadavers were implanted with stones of known size and/or composition and imaged with KUB, DT, and NCCT. Four blinded readers (2 urologists, 2 radiologists) evaluated KUBs for presence and/or location of calculi. They then re-evaluated with addition of tomograms to assess additional value. After a memory extinction period, readers evaluated NCCT images. Accuracy of detection was determined using nearest-neighbor match with generalized linear mixed modeling. ResultsTotal of 59 stones were identified on reference read. Overall, NCCT and DT were both superior to KUB alone (P < .001) while the difference between DT and NCCT was not significant (P = .06). When evaluating uric acid stones, NCCT and DT outperformed KUB (P < .01 and P < .05, respectively) while DT and NCCT were similar (P = .16). Intrarenal stones were better evaluated on DT and NCCT (P < .001 compared to KUB), while DT and NCCT were similar (P = 1.00). Accuracy was lower than anticipated across modalities due to use of the cadaver model. ConclusionOur study demonstrates DT is superior to KUB for identification of intrarenal calculi and could replace routine use of KUB or NCCT for detecting renal stones, even those composed of uric acid.

Low-dose noncontrast computed tomography in adults with acute appendicitis

Background: Computed tomography (CT) is now considered the imaging modality of choice for acute abdomen. However, with the increasing concern for exposure to ionizing radiation and its related risk of cancer in long run, low-dose CT has come up in recent studies with the attempt to minimize the effective radiation dose, yet giving the similar diagnostic yield. Aim: The aim of this study was to evaluate the diagnostic performance of low-dose noncontrast multidetector CT in adult patients with suspected acute appendicitis in relation to patients' body mass index. Materials and Methods: Eighty-three adult patients with suspected acute appendicitis were subjected to both standard and low-dose abdominal noncontrast CT (NCCT). The images were interpreted independently by two radiologists (blinded). Data collected were summarized and statistically analyzed. P Results: With low-dose NCCT abdomen, appendix was visualized in 80 patients (96.4%), with nonvisualization in 3 patients (3.6%), which was similar to standard dose. Low-dose NCCT has an overall sensitivity of 98.2% and a specificity of 100% in the diagnosis of acute appendicitis. Only one false-negative case and zero false-positive case was found, considering 6 mm as the cutoff value in appendiceal diameter with associated fat stranding. Alternative diagnoses were found in 22 (10 females and 12 males) patients. Conclusion: Low-dose NCCT abdomen was found highly accurate in diagnosing acute appendicitis with achievement of significant radiation dose reduction (about 88%) and thus can be recommended as a fast, safe, and cost-effective initial imaging technique in patients with right lower quadrant pain.

Value of contrast CT in combination with PET/CT in mesothelioma staging: Optimal protocol for initial assessment

PurposeTo assess the value of contrast enhanced CT (ceCT) when added to positron emission tomography combined with the standard low-dose non-contrast CT (PET/CT) protocols for staging patients with malignant pleural mesothelioma (MPM). MethodsRetrospective analysis of 47 patients with pathologically proved MPM. All patients underwent PET/CT with low dose CT followed by ceCT. PET/CT and ce-CT were evaluated separately then in combination. All the results were validated either by histopathology and/or clinical-radiological follow-up. Staging was performed based on TNM system. ResultsFor T-stage, the sensitivities for PET/CT, ceCT and combined PET/CT-ceCT were 89.1%, 86.9%, and 97.5%, respectively, p=0.04. Regarding nodal stage, the sensitivity, specificity and accuracy for PET/CT were 88.5%, 90.5%, and 89.4%; for ceCT 73.1%, 95.2% and 82.9%; and for PET/CT-ceCT 96.2%, 95.2% and 95.7%, respectively. PET/CT-ceCT significantly associated with the sensitivity, p=0.05. Considering the metastatic disease, the sensitivity, specificity and accuracy for PET/CT were 81.3%, 96.8%, and 91.5%; for ceCT 56.3%, 90.3% and 78.7%; and for PET/CT-ceCT 93.8%, 96.8% and 95.7%, respectively. PET/CT-ceCT significantly improved the sensitivity (p=0.03) and accuracy (p=0.02). Furthermore, combined PET/CT-ceCT significantly identified patients not suitable for surgery. ConclusionThe addition of ceCT to PET/CT protocol has significantly contributed to the staging of MPM.

Urolithiasis in pregnancy

Clinicians are faced with multiple diagnostic and treatment challenges when managing pregnant women with urolithiasis. Anatomical and physiological changes during pregnancy have to be taken into account whilst simultaneously considering both the expectant mother and the foetus. Ultrasonography remains the first-choice imaging modality, notwithstanding its potentially poor diagnostic accuracy. There is currently no consensus on second-line investigation for suspected urolithiasis. Low-dose non-contrast CT is highly sensitive, but the long-term effects of ionizing radiation on the foetus remain unknown. As far as treatment is concerned, expectant therapy is the primary option for management in the majority of cases. Percutaneous nephrostomy or ureteric stent placements are safe temporizing measures in relieving an acutely obstructed system and should be expedited in the presence of sepsis. Studies have shown ureteroscopy to be safe and effective during pregnancy with no significant risk to the foetus. It is important for the clinician to explain clearly the risks associated with the investigation and management options to the pregnant patient, including an acknowledgement that some of these remain unquantified, or even unknown.

Skeletal Metastasis as Detected by 18F-FDG PET with Negative CT of the PET/CT: Frequency and Impact on Cancer Staging and/or Management.

The aim of our study is to assess the frequency of detection of PET-positive computed tomography (CT)-negative skeletal metastases (SM) and determine the impact of such detection on staging and/or management in patients who had FDG PET/CT as part of the cancer work-up. We retrospectively reviewed 2000 18F-FDG PET/CT scans of known cancer patients. A log was kept to record cases of suspected SM with or without bone changes from the low-dose non-contrast CT. The presence or absence of SM was evaluated based on available pathological and clinical data. The impact of detection of such lesions on cancer staging and/or management was evaluated by a board certified oncologist. Of the 2000 cases, 18F-FDG PET/CT suggested SM in 146/2000 (7.3%). Of those 146 cases, 105 (72%) were positive on both PET and CT. The remaining 41 (28%) had PET-positive CT-negative bone lesions. SM was confirmed in 36/41 (88%) PET-positive/CT-negative cases. This was based on biopsy, imaging, or clinical follow-up. The detection of PET-positive CT-negative SM did not change staging or management in 7/36 (19.4%). However, staging and/or management was affected in 29/36 (80.6%). SM is not uncommon in 18F-FDG PET/CT, as it accounts for 146/2000 (7.3%) of cases. PET demonstrated FDG-avid SM without a CT abnormality in at least 36/146 (25%). Patients staging and/or management changed in 29/36 (80.5%). We concluded that 18F-FDG PET is sensitive in the detection of SM with significant impact on staging and/or management.