Anna L. Falkowski

Initial Results of a Single-Source Dual-Energy Computed Tomography Technique Using a Split-Filter: Assessment of Image Quality, Radiation Dose, and Accuracy of Dual-Energy Applications in an In Vitro and In Vivo Study.

ObjectiveThe aim of this study was to investigate the image quality, radiation dose, and accuracy of virtual noncontrast images and iodine quantification of split-filter dual-energy computed tomography (CT) using a single x-ray source in a phantom and patient study. Materials and MethodsIn a phantom study, objective image quality and accuracy of iodine quantification were evaluated for the split-filter dual-energy mode using a tin and gold filter. In a patient study, objective image quality and radiation dose were compared in thoracoabdominal CT of 50 patients between the standard single-energy and split-filter dual-energy mode. The radiation dose was estimated by size-specific dose estimate. To evaluate the accuracy of virtual noncontrast imaging, attenuation measurements in the liver, spleen, and muscle were compared between a true noncontrast premonitoring scan and the virtual noncontrast images of the dual-energy scans. Descriptive statistics and the Mann-Whitney U test were used. ResultsIn the phantom study, differences between the real and measured iodine concentration ranged from 2.2% to 21.4%. In the patient study, the single-energy and dual-energy protocols resulted in similar image noise (7.4 vs 7.1 HU, respectively; P = 0.43) and parenchymal contrast-to-noise ratio (CNR) values for the liver (29.2 vs 28.5, respectively; P = 0.88). However, the vascular CNR value for the single-energy protocol was significantly higher than for the dual-energy protocol (10.0 vs 7.1, respectively; P = 0.006). The difference in the measured attenuation between the true and the virtual noncontrast images ranged from 3.1 to 6.7 HU. The size-specific dose estimate of the dual-energy protocol was, on average, 17% lower than that of the single-energy protocol (11.7 vs 9.7 mGy, respectively; P = 0.008). ConclusionsSplit-filter dual-energy compared with single-energy CT results in similar objective image noise in addition to dual-energy capabilities at 17% lower radiation dose. Because of beam hardening, split-filter dual-energy can lead to decreased CNR values of iodinated structures.

Do Chondral Lesions of the Knee Correlate with Bone Tracer Uptake by Using SPECT/CT?

PURPOSE To evaluate the correlation of bone tracer uptake as determined with single photon emission computed tomography (SPECT)/computed tomography (CT) and the size and severity of chondral lesions detected with magnetic resonance (MR) imaging of the knee. MATERIALS AND METHODS MR imaging and SPECT/CT images of 63 knee joints in 63 patients (mean age ± standard deviation, 49.2 years ± 12.7) with chondral or osteochondral lesions were prospectively collected and retrospectively analyzed after approval by the ethics committee. Chondral lesions were graded on MR images by using a modified Noyes grading scale (grade 0, intact; grade 1, fibrillations; grade 2, <50% defect; grade 3, >50% defect; and grade 4, grade three plus subchondral changes) and measured in two dimensions. Technetium 99m hydroxymethane diphosphonate SPECT/CT bone tracer uptake was volumetrically quantified by using validated software. Maximum values of each subchondral area (patellofemoral or medial and lateral femorotibial) were quantified, and a ratio was calculated in relation to a reference region in the femoral shaft, which represented the bone tracer uptake background activity. Grades and sizes of chondral lesions and bone tracer uptake were correlated by using an independent t test and analysis of variance (P < .05). RESULTS Bone tracer uptake was low (mean relative uptake, 1.64 ± 0.95) in knees without any present chondral lesion. In knees with grade 3 and 4 chondral lesions, the relative ratio was significantly higher (3.62 ± 2.18, P = .002) than in knees with grade 1 and 2 lesions (2.95 ± 2.07). The larger the diameter of the chondral lesion, the higher the bone tracer uptake. Higher grades of chondral lesions (grades 3 and 4) larger than 4 cm(2) (4.96 ± 2.43) showed a significantly higher bone tracer uptake than smaller lesions (<1 cm(2), 2.72 ± 1.43 [P = .011]; and 1-4 cm(2), 3.28 ± 2.15 [P = .004]). CONCLUSION SPECT/CT findings significantly correlate with the degree and size of chondral lesions on MR images. Grade 3 and 4 chondral lesions of the knee, as well as larger lesions, correlate with a high bone tracer uptake.

Isolated pancreatic tuberculosis: A case report and radiological comparison with cystic pancreatic lesions

Pancreatic tuberculosis is rare and can occur in the absence of evidence of tuberculosis elsewhere in the body. Here we review the radiological appearance of pancreatic tuberculosis and compare it with other cystic pancreatic lesions, including common lesions (pseudocysts, serous or mucinous cystadenomas, intraductal papillary mucinous neoplasm) and rare lesions such as solid pseudopapillary tumors, etc. Their typical localizations within the pancreas and their malignant potential are presented. Knowledge of these can assist radiologists and clinicians in selecting the best approach towards making the correct diagnosis.

Organ-based tube current modulation in a clinical context: Dose reduction may be largely overestimated in breast tissue.

AbstractObjectivesOrgan-based tube current modulation aims to reduce exposure to radiosensitive organs like the breasts by considering their anatomical location and altering tube current during rotation. Former phantom studies demonstrated a dose reduction of 20–37 %. Our study aimed to estimate the potential of dose reduction with this technique in relation to the actual location of breast tissue in a large clinical cohort.MethodsA 1-year cohort of chest CTs of females (N=1,263) was retrospectively evaluated. To estimate the relative dose effect, breast location was analysed by measuring the angle range of glandular tissue within the different dose zones. Relative exposure compared with constant tube current was calculated. Descriptive statistics and Wilcoxon-test were applied.ResultsOnly 63 % of angle range of glandular breast tissue was found inside the reduced dose zone. The estimated mean relative dose reduction was lower than observed in former phantom studies(16 % vs. 20–37 %) but still significant compared to constant tube current (p<0.0001).ConclusionsAlthough organ-based tube current modulation results in a significant reduction of breast exposure compared to non-modulated irradiation, the technique cannot unfold its full potential, because breast tissue is often located outside the reduced dose zone, resulting in significantly lower dose reduction than expected.Key Points• OBTCM results in significant dose reduction compared to constant tube current scans. • A substantial portion of glandular tissue lies outside the reduced dose zone. • Potential dose reduction using organ-based tube current modulation may be overestimated.

Pylephlebitis of a variant mesenteric vein complicating sigmoid diverticulitis

Pylephlebitis--suppurative thrombophlebitis of the portal and/or mesenteric veins--is a rare complication of abdominal infections, especially diverticulitis. It can lead to severe complications such as hepatic abscess, sepsis, peritonitis, bowel ischemia, etc., which increase the mortality rate. Here we present a case of suppurative thrombophlebitis of the inferior mesenteric vein, as a complication of sigmoid diverticulitis. The epidemiology, clinical and radiological features as well as treatment strategies are discussed. We also review the anatomy of the mesenteric vein given its anatomic variation in the present case and how this anatomic knowledge might influence the operative approach should surgery be necessary.

Comparison of image quality and radiation dose between split-filter dual-energy images and single-energy images in single-source abdominal CT

ObjectivesTo compare image quality and radiation dose of abdominal split-filter dual-energy CT (SF-DECT) combined with monoenergetic imaging to single-energy CT (SECT) with automatic tube voltage selection (ATVS).MethodsTwo-hundred single-source abdominal CT scans were performed as SECT with ATVS (n = 100) and SF-DECT (n = 100). SF-DECT scans were reconstructed and subdivided into composed images (SF-CI) and monoenergetic images at 55 keV (SF-MI). Objective and subjective image quality were compared among single-energy images (SEI), SF-CI and SF-MI. CNR and FOM were separately calculated for the liver (e.g. CNRliv) and the portal vein (CNRpv). Radiation dose was compared using size-specific dose estimate (SSDE). Results of the three groups were compared using non-parametric tests.ResultsImage noise of SF-CI was 18% lower compared to SEI and 48% lower compared to SF-MI (p < 0.001). Composed images yielded higher CNRliv over single-energy images (23.4 vs. 20.9; p < 0.001), whereas CNRpv was significantly lower (3.5 vs. 5.2; p < 0.001). Monoenergetic images overcame this inferiority in CNRpv and achieved similar results compared to single-energy images (5.1 vs. 5.2; p > 0.628). Subjective sharpness was equal between single-energy and monoenergetic images and diagnostic confidence was equal between single-energy and composed images. FOMliv was highest for SF-CI. FOMpv was equal for SEI and SF-MI (p = 0.78). SSDE was significant lower for SF-DECT compared to SECT (p < 0.022).ConclusionsThe combined use of split-filter dual-energy CT images provides comparable objective and subjective image quality at lower radiation dose compared to single-energy CT with ATVS.Key points• Split-filter dual-energy results in 18% lower noise compared to single-energy with ATVS.• Split-filter dual-energy results in 11% lower SSDE compared to single-energy with ATVS.• Spectral shaping of split-filter dual-energy leads to an increased dose-efficiency.

Increased Magnetic Resonance Imaging Signal of the Lateral Patellar Facet Cartilage: A Functional Marker for Patellar Instability?

Background: In the knee joint, predisposition for patellar instability can be assessed by an abnormal Insall-Salvati index, tibial tuberosity–trochlear groove (TTTG) distance, and abnormal shape of patella and trochlea. Given the complex anatomic features of the knee joint with varying positions of the patella during motion, the presence of a single or even a combination of these factors does not inevitably result in patellar instability. After trocheoplasty in patients with trochlear dysplasia, assessment of trochlear cartilage and subchondral bone is limited due to postoperative artifacts. Identification of presence of edema in the patellar cartilage may be helpful to identify patellar instability before and after surgery in these patients. Purpose: To determine whether increased signal intensity of the lateral patellar facet cartilage or measurements of abnormal patellofemoral articulation are associated with patellar instability before and after trochleoplasty. Study Design: Case series; Level of evidence, 4. Methods: Twenty-two patients with clinical diagnosis of patellar instability who underwent trochleoplasty, with magnetic resonance imaging (MRI) of the knee before and after surgery, were identified. The following observations and measurements were obtained in preoperative imaging: Insall-Salvati ratio, tibial tuberosity–trochlear groove (TTTG) distance, patellar shape (Wiberg), trochlear shape (Hepp), and edema in the lateral patellar facet cartilage. At 3 to 12 months after surgery, the presence or absence of edema in the cartilage of the lateral facet of the patella, the trochlear shape, and TTTG distance were reassessed. Wilcoxon matched-pairs signed rank test and Student t test were used. Interreader agreement was calculated as the Cohen κ or paired Student t test. Results: Increased cartilage signal was present in 20 patients before trochleoplasty and in 4 after trochleoplasty. Insall-Salvati ratio was greater than 1.20 in 20 patients. Patellar shape was greater than type 2 in 18 patients. Trochlear shape was greater than type 2 in 21 patients before and 7 after trochleoplasty. Mean TTTG distance was 14 mm before and 10 mm after surgery. When results before and after surgery were compared, a significant difference was found for cartilage signal, TTTG distance, and trochlear shape. Agreement for observations was moderate to substantial, and no significant differences were found for interreader agreement (P > .05). Conclusion: Patellar cartilage at the lateral facet of the patella can be assessed after trochleoplasty despite postoperative artifacts in the trochlea. A decrease of patellar edema seems to be associated with improved femoropatellar articulation. Moreover, patellar edema may be used as a functional criterion of patellofemoral instability. This would provide additional information compared to morphologic criteria which just describe predisposing factors for femoropatellar instability.

Chronic Osteomyelitis Due to Tissierella carlieri: First Case

A 54-year-old woman sustained an open fracture of the right femoral shaft after a bicycle accident in 1985. Several operations were performed, the last including internal fixation using a plate and screws. In 2002, acute diverticulitis was treated with ciprofloxacin/metronidazole. In 2007, she presented with pain and swelling of the right thigh. Plain radiographs showed radiolucent femoral areas (Figure ​(Figure1a1a and b). Treatment was with debridement and removal of orthopedic hardware except for a difficult-to-remove screw fragment. Gentamicin beads were temporarily placed along the femur. Eight intraoperative specimens showed no growth after 10 days. Because of poor wound healing, a computed tomography scan was obtained, showing a sinus tract, femoral cortical defects, and intramedullary air (Figure ​(Figure1c–e).1c–e). Additional debridement was done; cultures of intraoperative biopsy specimens again remained sterile. Amoxicillin/clavulanate was prescribed for 2 weeks, and ciprofloxacin/rifampin was prescribed for 10 weeks.

Meniscal pathologies on MRI correlate with increased bone tracer uptake in SPECT/CT

ObjectivesTo assess the relationship of subchondral bone tracer uptake (BTU) on SPECT/CT and meniscal pathologies on MRI in patients with painful knees.MethodsTwenty-five patients who had MRI and SPECT/CT within 3 months without knee surgery or grade ≥3 cartilage lesions were prospectively included. Maximum values of each subchondral femorotibial area were quantified and a ratio was calculated in relation to a femoral shaft reference region, which represented the BTU background activity. Meniscal lesions were graded (intact/degeneration/tear) and meniscal extrusion (no/yes) was assessed using MRI by two musculoskeletal radiologists blinded to the SPECT/CT findings. One-tailed Spearman correlations served for statistics (p < 0.05).ResultsKnees with meniscal degeneration or tear showed a significantly higher BTU in the medial femorotibial compartment (p = 0.045) when compared to intact menisci. Meniscal degeneration was associated with an increased BTU in the lateral femorotibial compartment; however, this was not statistically significant (p = 0.143). Patients with an extruded meniscus showed significantly higher BTU compared to a non-extruded meniscus (p < 0.020).ConclusionsMedial femorotibial BTU in SPECT/CT was associated with meniscal pathologies. Highest BTU was found in patients with meniscal tears. SPECT/CT appears to be a useful imaging modality to identify patients with overloading or early osteoarthritis.Key Points•Meniscal degeneration and tears correlate significantly with increased BTU using SPECT/CT.•Medial meniscus extrusion is associated with an increased BTU in SPECT/CT.•SPECT/CT allows detection of overloading and early osteoarthritis.

Greater Trochanteric Pain Syndrome: Abductors, External Rotators

Abstract Chronic pain and tenderness at the greater trochanter characterizes trochanteric pain syndrome. For a long time, trochanteric bursitis was thought to be the only underlying pathology; however, investigations have shown that tendinopathy of the abductors is the main cause, followed by iliotibial band thickening and, to a lesser extent, abductor tendon tears. Trochanteric bursitis can be associated with it. On magnetic resonance imaging (MRI), peritrochanteric T2 abnormalities are evident in greater trochanteric pain syndrome. However, this is also frequently encountered in asymptomatic patients. In the postoperative setting, patients with total hip arthroplasties and transtendinous lateral or posterior surgical access are prone to tendon injury. Symptomatic patients typically present with tendon tears, whereas peritrochanteric fluid, thickening, and signal alterations of the abductors and fatty atrophy of the gluteus minimus muscle are often encountered in asymptomatic postoperative hips. MRI and ultrasound are proven and reliable imaging modalities in patients with greater trochanteric pain syndrome. Awareness of typical imaging findings, in particular in postoperative patients, are helpful in the evaluation of patients.