Reliability and accuracy of straightforward measurements for liver volume determination in ultrasound and computed tomography compared to real volumetry.

To evaluate the suitability of volume index measurement (VI) by either ultrasound (US) or computed tomography (CT) for the assessment of liver volume. Fifty-nine patients, 21 women, with a mean age of 66.8 ± 12.6 years underwent US of the liver followed immediately by abdominal CT. In US and CT imaging dorsoventral, mediolateral and craniocaudal liver diameters in their maximum extensions were assessed by two observers. VI was calculated by multiplication of the diameters divided by a constant (3.6). The liver volume determined by a manual segmentation in CT ("true liver volume") served as gold standard. True liver volume and calculated VI determined by US and CT were compared using Bland-Altman analysis. Mean differences of VI between observers were - 34.7% (- 90.1%; 20.7%) for the US-based and 1.1% (- 16.1%; 18.2%) for the CT-based technique, respectively. Liver volumes determined by semi-automated segmentation, US-based VI and CT-based VI, were as follows: 1.500 ± 347cm3; 863 ± 371cm3; 1.509 ± 432cm3. Results showed a great discrepancy between US-based VI and true liver volume with a mean bias of 58.3 ± 66.9%, and high agreement between CT-based VI and true liver volume with a low mean difference of 4.4 ± 28.3%. Volume index based on CT diameters is a reliable, fast and simple approach for estimating liver volume and can therefore be recommended for clinical practice. The usage of US-based volume index for assessment of liver volume should not be used due to its low accuracy of US in measurement of liver diameters.

Simple diameter measurement as predictor of liver volume and liver parenchymal disease.

To investigate the accuracy of liver diameters for estimation of liver size and to evaluate their application as tool for assessment of parenchymal liver disease. In the course of a population-based study, (SHIP) one thousand nine hundred thirty-nine volunteers underwent magnetic resonance imaging (MRI) of the liver including 3D gradient echo MRI sequences. Maximum liver diameters were measured in cranio-caudal (CC), anterior-posterior (AP), medial-lateral (ML) orientation. Diameters were compared with true liver volume assessed by liver segmentation. Additionally, age-dependent reference values for diameters were defined. Finally, accuracy of liver diameters was assessed to discriminate volunteers with healthy livers and participants with parenchymal changes, measured by MRI and laboratory. Reference values of liver diameters within the healthy population (n = 886) were defined as follows (mean ± standard deviation, confidence interval CI in cm): CC 17.2 ± 2, CI 13.6/21.2; AP 15.8 ± 1.9, CI 12.6/19.8; ML 19.7 ± 2.3, CI 15.8/24.6. There was a poor correlation using linear regression between liver diameter and true liver volume; CC 0.393, AP 0.359; ML 0.137. The AP direction shows the best correlation to discriminate between healthy and pathologic liver changes; AUC 0.78; p < 0.001, CC AUC 0.53; p < 0.001 and ML AUC 0.52; p = 0.008. Measurement of liver diameter, especially in the anterior-posterior direction is a simple option to detect chronic liver disease but less suitable for prediction of liver volume.

Bone block augmentation from the iliac crest for treatment of deep osteochondral defects of the knee resembles biomechanical properties of the subchondral bone.

PURPOSE: Bone block augmentation from the iliac crest can be used for reconstruction of the osteochondral unit to restore the underlying subchondral bone upon restoration of the cartilaginous layer via matrix-induced chondrocyte transplantation. To critically understand the successful restoration of the defect, biomechanical and histological analysis of the implanted bone blocks is required. The aim of the study was to analyse the ability of the bone block technique to restore huge bone defects by mimicking the physiological subchondral zone. METHODS: The experiments were performed using lateral femoral condyles and iliac crest bone grafts from the same cadavers (n = 6) preserved using the Thiel method. CT scans were made to evaluate bone pathology. Bone mineral density of all specimens was evaluated in the femoral head prior to testing. A series of tests were conducted for each pair of specimens. A static compression test was performed using an electro dynamic testing machine with maximal strength and failure behavior analyzed. Biomechanical tests were performed in the medial-lateral direction for iliac crest and for femoral condyles with and without removal of the cartilage layer. Histological analysis was performed on decalcified specimens for comparison of the condyle at lesion site and the graft. RESULTS: No significant difference in failure load could be found for iliac crest (53.3-180.5 N) and femoral condyle samples upon cartilage removal (38.5-175.1 N) (n.s.). The femoral condyles with an intact cartilage layer showed significantly higher loads (118.3-260.4N) compared to the other groups indicating that native or regenerated cartilage can further increase the failure load (p < 0.05). Bone mineral density significantly influenced failure load in all study groups (p < 0.05). Histological similarity of the cancellous bone in the femoral condyle and in the iliac crest was observed. However, within the subchondral zone, there was a higher density of sponge like organized trabeculae in the bone samples from the iliac crest. Tide mark was only detected at the osteochondral interface in femoral condyles. CONCLUSION: This study demonstrated that, bone blocks derived from the iliac crest allow a biomechanical appropriate and stable restoration of huge bony defects by resembling the subchondral zone of the femoral condyle. Therefore, bone augmentation from the iliac crest combined with matrix-induced autologous chondrocyte transplantation seems to be a reasonable method to treat these challenging injuries.

Reference values of liver volume in Caucasian population and factors influencing liver size.

PURPOSE: To investigate factors influencing liver size and to determine reference values of liver volume (LV) for healthy subjects. METHODS: 2773 volunteers underwent magnetic resonance imaging (MRI) of the liver in the setting of the population based Study of Health in Pomerania. Based on measurement of maximum diameters in three orientations, LVs were calculated and correlated with demographic factors such as age, gender, and body mass index. In addition, LVs of healthy volunteers and participants with parenchymal liver diseases such as fatty liver disease, iron overload, fibrosis/cirrhosis were compared. Adjusted reference values of liver volumes were defined for the group of healthy participants. RESULTS: In general, mean LV (mean ±â€¯standard deviation) was 1505 ±â€¯385 cm3. Age, gender and body mass index correlated significantly with the liver volume (p ≤ 0.001). Parenchymal liver diseases significantly influence LV (with: 1624 ±â€¯420 cm3, n = 1525 and without parenchymal liver diseases: 1360 ±â€¯273 cm3; n = 1.248, p ≤ 0.001). Compared to LV of participants without liver diseases, LV was increased in volunteers with hepatic steatosis (1717 ±â€¯419 cm3; n = 1111), liver iron overload (1558 ±â€¯367 cm3; n = 553; p ≤ 0.001) as well as in participants with fibrosis/cirrhosis (1494 ±â€¯459 cm3; n = 383). CONCLUSIONS: LV is influenced by age, body mass index and parenchymal liver diseases. Reference values were established to aid in the diagnosis of parenchymal liver diseases.

Accuracy of simple approaches to assessing liver volume in radiological imaging.

OBJECTIVES: The purpose of the study was to evaluate the accuracy of measured diameters and calculated volume indices for determining liver size and to derive a simple approach for estimating liver volume. METHODS: Three hundred twenty-nine volunteers (cohort A) were grouped according to liver volume: small (n = 109), medium (n = 110), and large (n = 110). True liver volume was determined by magnetic resonance imaging (MRI) using manual segmentation. Maximum diameters (maxdiam) of the liver and distances in midclavicular line (MCL) were measured. Volume indices were calculated as a simple product of the measured diameters. The calculated volume indices were calibrated to predict true liver volume. Performance of the calibrated method was evaluated in a control group (cohort B) including randomly selected volunteers (n = 110) and a patient group with histopathologically proven parenchymal liver diseases (n = 28). RESULTS: In cohort A, there was strong correlation between diameters and true liver volume (r s = 0.631-0.823). Calculated volume indices had slightly better correlation (maxdiam r s = 0.903, MCL r s = 0.920). A calibration index was calculated from the volumes and diameters determined in cohort A. Application of this calibration on cohort B verified a very strong correlation between calibrated volume indices and true liver volume (maxdiam r s = 0.920, MCL r s = 0.909). In addition, the low mean difference between predicted liver volume (maxdiam = -70.9 cm(3);MCL = -88.4 cm(3)) and true liver volume confirms that the calibrated method allows accurate assessment of liver volume. CONCLUSIONS: Both simple diameters and volume indices allow estimating liver size. A simple calibration formula enables prediction of true liver volume without significant expense.

Percutaneous treatment of biliary complications in pediatric patients after liver transplantation.

PURPOSE: Evaluation of the efficiency and safety of the percutaneous treatment of biliary complications in pediatric liver transplant recipients. METHODS: We conducted a retrospective analysis of children who underwent biliary percutaneous interventions after pediatric liver transplantation (PLT) over a 4-year period. Kind of biliary complication, interval between liver transplantation and intervention, status of the vessels, procedural interventional management, technical and clinical success, course of cholestasis, PTBD-related complications and patient survival were analyzed. RESULTS: 23 percutaneous transhepatic biliary drainages (PTBD) were placed in 16 children due to 18 biliary complications. The drains were customized individually by shortening and cutting additional holes. PTBD placement was performed with technical and clinical success in all children. 4 children received PTBD to bridge the time to retransplantation and surgical revision. One child received PTBD for successful treatment of anastomotic leakage. Long-term dilation of biliary stenoses was performed in 13 children using PTBD. One of these 13 patients showed recurrent stenosis during a median follow-up of 295 days. Bilirubin values decreased significantly after PTBD placement for biliary stenosis. One patient suffered from bacteremia after PTBD replacement. CONCLUSION: PTBD treatment for biliary complications after PLT is effective and safe.

Dual-energy computed tomography after endovascular aortic aneurysm repair: the role of hard plaque imaging for endoleak detection.

OBJECTIVES: To assess the diagnostic accuracy of dual-energy computed tomography (DECT) for detection of endoleaks and aneurysm sac calcifications after endovascular aneurysm repair (EVAR) using hard plaque imaging algorithms. MATERIALS AND METHODS: One hundred five patients received 108 triple-phase contrast-enhanced CT (non-contrast, arterial and delayed phase) after EVAR. The delayed phase was acquired in dual-energy and post-processed using the standard (HPI-S) and a modified (HPI-M) hard plaque imaging algorithm. The reference standard was determined using the triple-phase CT and contrast-enhanced ultrasound. All images were analysed separately for the presence of endoleaks and calcifications by two independent readers; sensitivity, specificity and interobserver agreement were calculated. RESULTS: Endoleaks and calcifications were present in 25.9 % (28/108) and 20.4 % (22/108) of images. The HPI-S images had a sensitivity/specificity of 54 %/100 % (reader 1) and 57 %/99 % (reader 2), the HPI-M images of 93 %/92 % (reader 1) and 96 %/92 % (reader 2) for detection of endoleaks. For detection of calcifications HPI-S had a sensitivity/specificity of 91 %/99 % (reader 1) and 95 %/97 % (reader 2), the HPI-M images of 91 %/99 % (reader 1) and 91 %/99 % (reader 2), respectively. CONCLUSION: Using HPI-M, DECT enables an accurate diagnosis of endoleaks after EVAR and allows distinguishing between endoleaks and calcifications with high diagnostic accuracy. KEY POINTS: • Dual-energy computed tomography allows the diagnosis of aortic pathologies after EVAR. • Hard plaque imaging algorithms can distinguish between endoleaks and aneurysm sac calcifications. • The modified hard plaque imaging algorithm detects endoleaks with high diagnostic accuracy.

Hand-carried and high-end ultrasound systems are equally inferior to abdominal radiography and multidetector computed tomography in the diagnosis of pneumoperitoneum.

PURPOSE: Pneumoperitoneum (PP) is a severe finding in emergency departments. Its quick and correct diagnosis is indispensable for the further treatment of patients. The aim of this study was to analyze the clinical value of abdominal ultrasound performed with a modern hand-carried ultrasound (HCU) device as well as with a high-end ultrasound (HUS) system in the diagnosis of PP in patients with acute abdominal pain. MATERIALS AND METHODS: 31 patients with acute abdominal pain were enrolled in this study irrespective of their underlying disease, and examination with a latest generation HCU and a newest generation HUS was performed. Diagnosis of PP was based on findings of multidetector computed tomography (MDCT) and abdominal radiography (AR) as the standard of reference. The study was carried out by two independent and experienced examiners unaware of the diagnosis made by MDCT or AR. RESULTS: In five (16 %) patients PP was identified by MDCT and AR. Examination with HCU was calculated with a sensitivity and specificity of 80 % and 81 %, respectively. Examination with HUS yielded a sensitivity and specificity of 80 % and 89 %, respectively. CONCLUSION: PP can be detected by HCU and HUS with almost equal accuracy in patients with acute abdominal pain but both methods are inferior compared to MDCT and AR. However, HCU and HUS can accelerate the triage of patients and help to make decisions regarding the necessity of further examinations without the need for radiation and while reducing economic and logistic resources. KEY POINTS: 1. Pneumoperitoneum (PP) is a severe finding in emergency departments. 2. Hand-carried (HCU) and high-end (HUS) ultrasound systems can be helpful in detecting PP. 3. Abdominal radiography (AR) and multidetector computed tomography (MDCT) are superior in detecting PP. 4. HCU and HUS can accelerate the triage of patients. 5. HCU and HUS can be helpful when making decisions regarding the necessity of further examinations.

Percutaneous transhepatic and transsplenic portal vein access: embolization of the puncture tract using amplatzer vascular plugs.

PURPOSE: To report on first results of the embolization of transhepatic and transsplenic puncture tracts using an Amplatzer Vascular Plug (AVP) after percutaneous portal vein intervention. MATERIALS AND METHODS: Embolization of transhepatic and transsplenic puncture tracts with AVP was attempted in 5 patients (3 females; age range: 3 - 71 years). Portal vein access was gained by a transhepatic (n = 4) or transsplenic (n = 1) approach, and stenosis (n = 2) or thrombosis (n = 3) of the portal vein was successfully treated by percutaneous stenting or thrombus aspiration and thrombolysis using 6 to 10 French sheaths. Due to the relatively large bore and/or short transparenchymal puncture tracts, it was considered favorable to use AVPs as an embolic agent. The medical records, the radiological reports and images of these 5 patients were retrospectively evaluated. RESULT: In three cases one AVP II (diameter, 4 mm), in one case one AVP IV (diameter, 4 mm) and in one case two AVPs II (diameter, 8 and 6 mm) were used for embolization of the puncture tract. In all five cases embolization was technically successful. There was no bleeding from the puncture tract. During a median follow-up of 14 months (range, 21 days to 21 months), one patient developed a focal liver abscess adjacent to the AVP which was successfully treated by antimicrobial and drainage therapy. There were no further embolization-related complications. CONCLUSION: AVPs are suited to embolize large bore and/or short transhepatic and transsplenic puncture tracts effectively, safely, and precisely. Caution is required in patients with an increased risk for infectious complications. KEY POINTS: • Embolization of transhepatic and transsplenic puncture tracts with AVPs is feasible• Large and/or short puncture tracts can be effectively embolized with AVPs• The risk of infectious complications has to be considered Citation Format: • Dollinger M, Goessmann H, Mueller-Wille R et al. Percutaneous Transhepatic and Transsplenic Portal Vein Access: Embolization of the Puncture Tract Using Amplatzer Vascular Plugs. Fortschr Röntgenstr 2014; 186: 142 - 150.

[Percutaneous thrombus aspiration and thrombolysis for the treatment of acute portal vein thrombosis in a 5-year-old child]. / Akute Pfortaderthrombose bei einem 5-jährigen Kind: Rekanalisierung mittels perkutaner Thrombenaspiration und Thrombolyse.

Early portal vein thrombosis is a frequent and severe complication following pediatric liver transplantation. The clinical presentation is characterized by signs and symptoms of portal hypertension such as ascites and digestive hemorrhage. Primary treatment consists of heparin therapy. In the case of persistent or progressive thrombosis or symptoms, surgical thrombectomy or retransplantation should be considered. However, surgical intervention is associated with significant morbidity and mortality. We report on successful minimally invasive percutaneous thrombus aspiration and thrombolysis for the treatment of acute portal vein thrombosis in a 5-year-old child post liver transplantation.

Diagnosis of pericardial effusion with a new generation hand-carried ultrasound device in cardiothoracic intensive care unit patients.

BACKGROUND: Technological advances introduced hand-carried ultrasound (HCU) imagers in daily clinical workflow providing several benefits such as fast bedside availability and prompt diagnosis. PURPOSE: To evaluate the diagnostic yield of a latest generation HCU imager compared to contrast-enhanced multidetector computed tomography (MDCT) for the detection of pericardial effusion (PE) in cardiothoracic intensive care unit (ICU) patients. MATERIAL AND METHODS: Thirty-six patients from a cardiothoracic ICU were enrolled to this study irrespective of their underlying disease. All patients were examined with a new generation HCU for the presence of PE. Definite diagnosis of PE was based on findings of MDCT as standard of reference. Statistical analysis was performed using PASW 18. RESULTS: PE was identified in 20 patients by MDCT (prevalence 56%). The HCU examination was carried out technically successfully in all patients. Sensitivity, specificity, positive and negative predictive value of HCU for the diagnosis of PE were 75%, 88%, 88%, and 74%, respectively. CONCLUSION: HCU provides rapid, practical, reliable, and cost-effective diagnosis of PE in patients on cardiothoracic ICU.

Bedside diagnosis of pleural effusion with a latest generation hand-carried ultrasound device in intensive care patients.

BACKGROUND: Further development established hand-carried ultrasound (HCU) imagers in daily clinical workflow providing several advantages such as fast bedside availability and prompt diagnosis. PURPOSE: To evaluate the diagnostic yield of a latest generation HCU imager compared to chest radiography (CR) for the detection of pleural effusion (PE) in intensive care patients. MATERIAL AND METHODS: Forty-eight hemithoraces of 24 patients on surgical intensive care units were enrolled in this study. All hemithoraces were evaluated using both HCU and CR. Definite diagnosis of PE was achieved using a high-end ultrasound system as standard of reference. Statistical analysis was performed using 2 × 2 tables and a McNemar test. A P value of <0.05 was considered statistically significant. RESULTS: PE was present in 35 of 48 hemithoraces (73%). The HCU examination was carried out technically successfully in all hemithoraces. Sensitivity and specificity of HCU for the diagnosis of PE was 91% and 100%, respectively, whereas sensitivity and specificity of CR was 74% and 31%, respectively. The difference between HCU and CR was statistically significant with respect to specificity but not sensitivity (P = 0.008 and P = 0.11, respectively). CONCLUSION: Due to its ease of use and its high diagnostic yield HCU systems of the latest generation constitute a helpful technique for the primary assessment of PE.

[Superior vena cava occlusion : Radiological placement of a central venous port system via femoral vein access]. / Okklusion der V. cava superior : Radiologische Implantation eines zentralvenösen Portsystems über einen femoralen Zugang.

We report on a young patient with cancer of unknown primary origin with occlusion of the superior vena cava due to mediastinal lymphadenopathy. In order to continue infusion of palliative chemotherapy a central venous port system was radiologically implanted via a right femoral vein access. The port reservoir was placed craniomedial to the right anterior superior iliac spine. This approach was considered convenient in respect to comfort in wearing trousers. In addition, at this site the port reservoir is easily accessible for medical staff. It was possible to draw blood via the port system and to infuse the chemotherapy without complications. The present case shows that in cases of occlusion of the superior vena cava radiological implantation of a central venous port system via a femoral vein access is a useful option.

Endovascular treatment of acute arterial hemorrhage in trauma patients using ethylene vinyl alcohol copolymer (Onyx).

PURPOSE: This study was designed to determine the feasibility and efficacy of endovascular embolization with liquid embolic agent ethylene vinyl alcohol copolymer (Onyx) in patients with acute traumatic arterial bleeding. METHODS: This is a retrospective review of 13 patients (9 men and 4 women; mean age 45 years) with severe trauma who underwent embolotherapy using Onyx from November 2003 to February 2009. Bleeding was located in the pelvis (5 patients), kidney (3 patients), mesenteric region (2 patients), retroperitoneal space (2 patients), neck (1 patient), and thigh (1 patient). In three cases (23.1%), Onyx was used in conjunction with coils. We evaluate the technical and clinical success, procedural and embolization time, occurrence of rebleeding, and embolotherapy-related complications, such as necrosis or migration of Onyx into nontarget vessels. RESULTS: In all patients, embolotherapy was technically and clinically successful on the first attempt. Control of bleeding could be reached with a mean time of 19 (range, 4-63) min after correct placement of the microcatheter in the feeding artery. No recurrent bleeding was detected. No unintended necrosis or migration of Onyx into a nontarget region was observed. During the follow-up period, three patients (23.1%) died due to severe intracranial hemorrhage, cardiac arrest, and sepsis. CONCLUSIONS: Transcatheter embolization with new liquid embolic agent Onyx is technically feasible and effective in trauma patients with acute arterial hemorrhage.

Multidetector computed tomography mesentericography for the diagnosis of obscure gastrointestinal bleeding.

PURPOSE: To evaluate the diagnostic yield of 16-row multidetector computed tomography (CT) mesentericography in patients with obscure gastrointestinal bleeding. MATERIALS AND METHODS: The radiological information system database was used to retrospectively identify all patients in whom CT mesentericography (CTM) was performed for the diagnosis of obscure gastrointestinal bleeding between July 2002 and September 2006. A subsequent prospective study was conducted between October 2006 and September 2009 to evaluate CTM in patients with major obscure gastrointestinal bleeding. The retrospectively identified patients (six patients) as well as the prospectively evaluated patients (seven patients) constitute the study population. Following mesenteric DSA the catheter was left in the superior mesenteric artery, the patient was transferred to the CT suite and CTM was carried out by scanning the abdomen after contrast material injection via the catheter. Active bleeding was suspected if a focal area of high attenuation consistent with contrast material extravasation was found within the bowel lumen. RESULTS: CTM detected the site of active bleeding in three of 13 patients (23 %). In the subpopulation of patients who were prospectively evaluated, CT mesentericography identified the site of active bleeding in one of seven patients (14 %). Depiction of active bleeding by CTM prompted surgical intervention in each case and surgery confirmed the findings of CT mesentericography. CONCLUSION: Due to the relatively low rate of positive findings and inherent drawbacks, we feel that CTM cannot be recommended in general. However, in selected patients who are continuously bleeding at a low rate and in whom iv-CT was negative, CT mesentericography might be helpful.

Image fusion with volume navigation of contrast enhanced ultrasound (CEUS) with computed tomography (CT) or magnetic resonance imaging (MRI) for post-interventional follow-up after transcatheter arterial chemoembolization (TACE) of hepatocellular carcinomas (HCC): Preliminary results.

AIM: The assessment of the immediate post-interventional microcirculation and perfusion following transcatheter arterial chemoembolization (TACE) with new real time imaging fusion technique (VNav) of computed tomography (CT) or magnetic resonance imaging (MRI) with contrast enhanced ultrasound (CEUS) compared to follow-up. MATERIAL: Following TACE an image fusion of CEUS with CT or MRI of the liver was performed in 20 patients (18 men, 2 women; age 29-75 years) with confirmed hepatocelluar carcinoma (HCC) to evaluate the post-interventional tumor vascularization and perfusion of HCC tumor lesions. Image fusion with CEUS performed immediately was compared with the result at the end of TACE (DSA), with post TACE CT (non-enhanced CT within 24 hours) and with follow up CT (enhanced CT after 6 weeks) after embolization. Ultrasound was performed using a 1-5 MHz multifrequency SonoVue transducer (LOGIQ 9/GE) after a bolus injection of 2-4ml SonoVue® with contrast harmonic imaging (CHI). Thirteen examinations were fused with a contrast enhanced CT, 7 with a MRI performed before TACE. RESULTS: The post-interventional volume navigation image fusion of CT or MRI with CEUS showed differences regarding the residual tumor perfusion compared to other modalities. The correlation (Spearman-test) between the perfusion result at the end of TACE, non-enhanced CT after TACE and image fusion with CEUS was 0.42 and 0.50. The difference between the result at the end of TACE and the fusion with CEUS was significant (p < 0.05, Wilcoxon-test). The correlation between fusion of CEUS with CT/MRI and follow-up CT (after 6 weeks) was 0.64, the difference was not significant (p > 0.05). The differences between native CT within 24 hours after TACE and follow up CT after 6 weeks or fusion of CEUS and CT/MRI were significant (p < 0.05). The inter-observer variability was 0.61 at the end of TACE, 0.58 at non-enhanced CT (within 24 hours), 0.87 at fusion CEUS with CT/MRI and 0.74 at follow up CT after 6 weeks (Cohens Kappa test). CONCLUSION: Image fusion with volume navigation (VNav) of CEUS with CT or MRI allows an accurate localisation of foci in patients with HCC. This exact mapping permits an easier control and evaluation of the results after TACE. The fusion of CEUS and CT or MRI allows a better evaluation of the microcirculation and the residual tumor perfusion at an earlier point of time than usual modalities of therapy control like non-enhanced CT. This might lead to a more differentiated monitoring of therapy.